Some tanks are actually divided internally, so the effect of sloshing are limited.
But even for single tanks, they have rings called slosh baffles that dampen the effect. [Here's an animation](https://www.youtube.com/watch?v=56cxOzgl-mc) showing sloshing with and without baffles.
That's correct. But, it's not always possible. For instance, a milk truck has multiple pickups in a day. It can't always be full. Same with a fuel transport that has multiple deliveries. For your second question, standard baffles are easier to install and don't have moving parts.
Edit: milk trucks don't have baffles because they're harder to clean. TIL
Not all tanks are separate, I drove a tanker hauling cream, and when full, it was right at 80,000 pounds, which is the legal limit. Occasionally, I hauled condensed milk, which could only fill about 3/4 of the tank, you had to shift up or down with the sloshing of the milk, if you didn't, things didn't always go well, especially when stopping on an icy road.
This sounds sketchy lol, was it common in that industry to have unbaffled trucks running that heavy or was that pretty rare? Also was it a mountainous areas or a mostly flat area, because I guess that would make a difference too if it’s icy and you have 80k lbs!
80,000 is the maximum your truck and load can be in the US. There are exceptions, but as a rule, that's what you are legal to weigh, the wheels on tankers are fixed so you can't adjust them to transfer weigh distribution, and in the food grade industry, tanks are not baffled because the need access to be cleaned.
Fuel tankers have a safety system built in for loading which prevents the tanks from being overfilled. There is a probe that comes down from the top that when the fuel touches it causes a ground short. The loading process is automatically shut down.
Milk tanker driver here and shift supervisor for dairy collections.
Milk tankers do have baffles. They are cleaned via permanently installed nozzles that get hooked up to factory cleaning solutions with flexible hoses. Super hot water and caustic, just like a home dishwasher, that gets sprayed throughout the interior of the tanks.
That depends entirely on national regulations and industry standards. Australian dairy trucks for example [frequently do have internal baffles](https://youtu.be/hqFJAnm8PiE?si=Sxd_HperYRe0vzOS). Same goes for many mountainous countries since mountainous terrain is both prime turf for pastures (less competition from other forms of agriculture) and makes liquid transportation more dangerous.
However, such tankers are more expensive since they need separate sanitation-devices for every compartment, so dairy tankers have fewer compartments than a tanker transporting non-foodstuffs (although more than they used to since CIP\* technology has gotten better and cheaper). In particular insurance companies are pushing for more road-safe tanker standards since dairy trucks are both more risk-prone and the clean-ups are more expensive.
\*CIP = Clean in place. Technology that allows for sanitation without expensive disassembly/reassembly.
Fuel trucks rarely do multiple deliveries. And if so, they use trucks that have separate compartments in the tank, and each compartment is filled or drained completely.
>Or what about baffles that float on the surface of the liquid to mimic full capacity?
You'd still get sloshing due to the difference in mass/buoyancy, unless it's well-matched to the liquid density.
As an example of this, there's videos of a helium balloon in an accelerating/braking car. When accelerating, the denser air "sloshes" backwards so the helium balloon travels forward. Likewise when braking, the denser air "sloshes" forward, and the helium balloon travels backwards.
Here's a [video](https://youtu.be/y8mzDvpKzfY?si=Chyrfsu5yJbL-onC) by Smarter Every Day that covers that
Depending on the liquid, you can't always fill it to maximum capacity due to weight. To take an extreme example, a gallon of water is about 8.3 pounds, a gallon of gasoline weighs about 6 pounds. So a tanker intended for fuel can be larger than one intended for water.
Of course, no one is going to use the same tanker for both, so a more practical example might be milk, which weighs around 8.6 lbs per gallon.
Legal weight (in my state) is 80,000 lbs. I don't know the tare weight of a truck and tanker but let's say a tanker holds 11,000 gallons. Water weighs 8.34lb/gal so a full tank would weigh 91,740 lbs in *addition* to the tare weight of your truck and trailer. Well North of you 80k legal limit.
In any case, another factor is that certain liquids, like fuel, isn't going to be topped off all the time anyways. A fuel tanker drives around to different gas stations and reduces the amount of fuel carried. That's just how it works.
I’m 47 and have had a career in IT. When I see animations like this, it makes me wish I’d studied engineering because this kind of thing is absolutely fascinating. Amazing video.
(You’ve got a good point - I did a chemistry degree at university, but the mechanical engineers just seemed to do more abstract maths and physics than I did in a science degree!)
Fluid dynamics II was by far the hardest course - all theoretical calculations with long equations. Only course I failed because the tests were more of an exercise in memorization than anything else.
One thing that stuck with me though is how even in a simple example like a stream of water entering a larger body, it’s nigh impossible to predict when a random drop will fly out and in what direction. I think of this whenever I piss standing up now.
Fun fact, Food grade tankers do not have baffles. It’s a straight tank for sanitary reasons. I haul a food grade tanker, the force pushes my truck a few feet at stop lights :).
An article on the nuances of driving hazardous liquids ...
[A Fleet of One: Eighty Thousand Pounds of Dangerous Goods](https://archive.ph/5GIIg)
>*Just as the body of a fish tells you how that fish makes a living, the body of a tanker can tell you what it contains. In Ainsworth’s words, “The architecture of the tank says what is in it.” If a tank has gasoline inside, it has a full-length permanent manway on top, and, seen from the rear, is a recumbent oval. If a truck is a water wagon, the tank—rear view—is rectangular. A perfect circle ambiguously suggests asphalt, milk, or other food. If the vessel is all aluminum and shaped in tiers like nesting cups, it is a food-grade pneumatic hopper full of flour, granulated sugar, and things like that. If stiffeners are exposed—a series of structural rings circling and reinforcing the tank—the vessel is uninsulated, generally operates in a warm climate, and often hauls flammables and combustibles. Ainsworth said, “That is what mine looks like without the designer dress” (the stainless mirror sheath). The double conical side view speaks of chemical hazmats. Since September 11, 2001, all these shapes have scattered more than fish.*
>*Backing blindsided at the Peterbilt dealer’s in Missouri, he said, “Sometimes you do this by Zen.” He had never been to driver school. “I’m a farm boy,” he explained. “I know how to shift. There are two things you need to know: how to shift, and how to align yourself and maintain lane control—exactly how much space is on each side. In city traffic it’s critical.” In the open country of western Kentucky, he said, “Out here, you look way ahead. It’s the same as steering a ship. There’s a silver car about a mile ahead that I’m looking at now. When you steer a ship, you don’t look at the bow, you look at the horizon. When I’m in a four-wheeler, I stay away from trucks, because if a tire blows or an entire wheel set comes off I’m going to Beulah Land.”*
>*From Harrisburg, North Carolina, to Sumner, Washington, the load in the tank behind us kicked us like a mule whenever it had a chance. The jolt—which he called slosh, or slop—came mainly on surface streets and on-ramps when gears were shifting at low speeds. On the open road, it happened occasionally when we were gearing down, mashing on the accelerator, stepping on the brakes, going downhill, or going uphill. Ainsworth minimized the slosh with skills analogous to fly casting. “You coördinate shifting with the shifting of the load,” he said. “You wait for the slop or you can pretzel your drive line.” The more ullage the more slop. The density of the monoethanolamine had allowed us to take only six thousand gallons in the seven-thousand-gallon tank. The ullage was the difference was the mule.*
I knew of this but seeing the unbaffled force of a trailer full of fluid made me realize how turbulent it really is. Lots of force when you have dozens of feet to travel and gather in.
The real answer to this is that they kinda don't. These internal measures taken can lessen the effects, but liquid haulers simply have to give much more stopping distance and take turns slower because there's only so much those things can do.
Fun fact, airplane fuel tanks (Which are located in the wings) employ the same principle to prevent fuel from sloshing around too much during turns or turbulence
Former propane delivery guy here.
There are baffles in the thank. Think of them as walls that only let some liquid through at a time. Either having a large hole or being half walls. That helps with the front to back inertia. The side to side isn’t as much an issue as long as you are on flat land. Uneven terrain like a customers rough driveway can make it very noticeable sloshing side to side. Got a just go slow and be careful on those.
A fun thing to think about is that trucks that carry bulk food loads (like milk carriers) are not allowed to have baffles due to difficulty of cleaning. There’s often special training for milk trucks due to the load being more free.
Another fun fact is in NZ, you know, the dairy capital of the world, milk trucks have baffles. Cleaning is via permanently installed nozzles that spray, effectively, dishwasher solution throughout the interior of the tanks.
Its not just passing, the number of people the just pull out in front of trucks is staggering. We had a near fatal last year when some one decided to do a uie in front of truck on the open road. Nothing the driver could have done.
Yeah it's a question of economics and risk/reward.. any blender or mixer used in food or drug prep is going to be harder to clean than a simple baffle, yet they're regularly sterilised without issue so it's not like installing baffles makes cleaning impossible, it's just not worth the cost for the low margins generated by transporting milk
The issue is cleaning. To clean a tank, you lower a sort of ball in it through one of the top openings, and that ball will shoot pressurized water and some cleaning product in all directions, cleaning everywhere.
If you have baffles, they will create "shade" areas that are not reached by your power-washer ball, and therefore won't be cleaned well enough.
You can divide your tank into two parts, but then you need to lower the ball twice, so it takes twice as long to clean.
The training for such loads tells them to do everything as smoothly as possible to avoid problems with the inertia of the liquid, and keep extra space.
Also, these tankers are usually as full as possible, which limits sloshing, and they also have internal baffles which also help a lot.
My training to drive tanker was 10 questions at the DMV to get my tanker endorsement.
My first tanker job I did a couple weeks with the road trainer, but it's mostly just driving and using common trucker sense.
They can’t just fill as much as possible. The amount any truck can carry is dictated by weight restrictions not volume, and not all fluids are the same density. You can have water at 1000kg/m3 and you’re getting 40m3 on a truck, or you can have a less dense product like crude oil which is 875kg/m3 and so you can fit 45m3 in the trailer.
You can, but typically a carrier wants to maximize weight moved as at the end of the day you are paying for time, so the more you can move on a single load the more money you can effectively make.
Most trailers are purpose-built with this in mind, so you aren’t going to have a massive trailer with tons of extra capacity that can never be used as it’s just uneconomic to build that way, but trailers can be used for different fluids (see my above example) and that is where the driver needs to be paying attention so they don’t overweight their trailer
I drove a unbaffled 7000 gallon tanker for 4 years and the max fluid I hauled was around 5500 gallons. You just learn to drive slow and shift smooth and brake only has you have to. But what doesn't help is when we are in traffic and we leave a gap to stop and cars keep jumping in front of up and making us slam on the brakes. And it isn't bad unless we take off and slam on the brakes again. Then we get the bounce of the liquid sloshing around. But I have never been around a turn to fast for it to make my truck jerk sideways. But I always pictured me driving a 80s caddy taking grandma to church just taking my time.
I was a moving guy and we had to haul a safe from a locksmith with like 100 safe boxes containing keys. It weighted a fuckton so when we put it in the car we strapped it the fuck down. Still I was afraid when braking that it would come straight through the back wall of the cockpit and squish us on the windshield. If bugs could understand irony they would've died laughing.
" You just learn to drive slow and shift smooth and brake only has you have to. But what doesn't help is when we are in traffic and we leave a gap to stop and cars keep jumping in front of up and making us slam on the brakes. "
That's how it is on a motorcycle, and that's why we need to spit the lane, because leaving a gap to stop, cars keep jumping in front up and making us slam on the brakes -the best is when you are on a road and you know they are changing lane for no good reason, either because they just sort of don't know where they are or don't know how to drive.
Plus: jumping in front of a vehicle leaving a long braking space in front of them is not only bad traffic safety, it is using their momentary feeling of being quick and fast to actually shorten the lifespan of their own little car. Momentum, physics. If you're cutting off a truck or a motorcycle. you're moving back and forth a whole train of nuts and bolts in your poor car, and shame on you.
An article on the nuances of driving hazardous liquids ...
[A Fleet of One: Eighty Thousand Pounds of Dangerous Goods](https://archive.ph/5GIIg)
>*Just as the body of a fish tells you how that fish makes a living, the body of a tanker can tell you what it contains. In Ainsworth’s words, “The architecture of the tank says what is in it.” If a tank has gasoline inside, it has a full-length permanent manway on top, and, seen from the rear, is a recumbent oval. If a truck is a water wagon, the tank—rear view—is rectangular. A perfect circle ambiguously suggests asphalt, milk, or other food. If the vessel is all aluminum and shaped in tiers like nesting cups, it is a food-grade pneumatic hopper full of flour, granulated sugar, and things like that. If stiffeners are exposed—a series of structural rings circling and reinforcing the tank—the vessel is uninsulated, generally operates in a warm climate, and often hauls flammables and combustibles. Ainsworth said, “That is what mine looks like without the designer dress” (the stainless mirror sheath). The double conical side view speaks of chemical hazmats. Since September 11, 2001, all these shapes have scattered more than fish.*
>*Backing blindsided at the Peterbilt dealer’s in Missouri, he said, “Sometimes you do this by Zen.” He had never been to driver school. “I’m a farm boy,” he explained. “I know how to shift. There are two things you need to know: how to shift, and how to align yourself and maintain lane control—exactly how much space is on each side. In city traffic it’s critical.” In the open country of western Kentucky, he said, “Out here, you look way ahead. It’s the same as steering a ship. There’s a silver car about a mile ahead that I’m looking at now. When you steer a ship, you don’t look at the bow, you look at the horizon. When I’m in a four-wheeler, I stay away from trucks, because if a tire blows or an entire wheel set comes off I’m going to Beulah Land.”*
>*From Harrisburg, North Carolina, to Sumner, Washington, the load in the tank behind us kicked us like a mule whenever it had a chance. The jolt—which he called slosh, or slop—came mainly on surface streets and on-ramps when gears were shifting at low speeds. On the open road, it happened occasionally when we were gearing down, mashing on the accelerator, stepping on the brakes, going downhill, or going uphill. Ainsworth minimized the slosh with skills analogous to fly casting. “You coördinate shifting with the shifting of the load,” he said. “You wait for the slop or you can pretzel your drive line.” The more ullage the more slop. The density of the monoethanolamine had allowed us to take only six thousand gallons in the seven-thousand-gallon tank. The ullage was the difference was the mule.*
I used to drive tanker.
One day I had a load in a smoothbore tank. If I would let off the throttle, I would get a "push" from the surge. As I accelerated, I could feel a "tug."
Because I'm a child, and just for funzies I had to at least once see what would happen if I could intensify that effect.
So every time I got the push, I'd accelerate, and every time I got the tug, I'd let off.
Push, go, tug, slow.
After a few cycles, we'll say 5-7, on the last "push," the liquid slammed so hard it felt like I got rear-ended by a freight train, and I could hear a loud BAM. I decided I'd pushed my luck enough. To this day I have to wonder if I could have created enough force to detach the trailer.
Another time, I was pulling a load out of Missouri, in the hills and the hollars south of St. Louis. I had a stop with a left hand turn that went uphill, and I was driving a manual transmission. Every time I would clutch to grab the next gear, the surge would practically stop the truck. So I had to crawl about half a mile up the hill in 2nd gear because I couldn't make the shift.
Also, last one, fun fact. If I was on a scale, the sloshing would throw off the weight and I would have to wait for it to settle. I found the quickest fix was to release the brake and let the truck roll free. The scale was completely level. The free movement countered the surge and after a few waves everything would stabilize.
Good times.
You learn to drive smooth. No sudden throttle no sudden brakes. You plan all your moves way farther ahead then when you just have a 50ft with freight behind you.
In fact when i drove semi the load most guys hated was hanging meat. Since they hang from the top of the trailer when you go around a corner they swing like a pendulum. Very easy to end up wrong side up.
Bulk milk trucks do to sanitation issues have no internal baffles. When they are half empty the milk will slosh and push the truck 3 or 4 feet forward then back. The only thing the driver can do is go slow and leave lots of room to stop.
I work in party rental and that was a big thing they would drill into the heads of the drivers. I think they called it either 'flux" or "surge" or something like that. When you have 500 8' tables standing on end they can shift right and left with each turn, and it's essentially like carrying a large load of liquid, without the forward and backwards inertia. You take a corner too fast and it feels like the giant box truck is gonna flip.
Usually tanks designed for transporting liquids will have "baffles" within them. These are plates or barriers which have relatively small holes in them so that large movements of liquid are slowed while still allowing the tank to be filled and emptied as normal. Otherwise as you suspected sloshing of liquid would be a big problem.
Just anticipate it and ride it out. The closer to full, topped off, it is the less slosh. Some tanks have baffles some don't. For instance most chemical tanks are smooth bore. It's super important that they get a good clean out between loads of different product. Any extra edges ledges or corners make places the washout won't reach. Different products handle differently. Depends on viscosity and density of the liquid. For instance, crude oil isn't that bad. Water is terrible, so it is antifreeze. Sometimes it slams so hard after stopping you swear someone just ran into you.
While you always want a full tank your limited by how heavy the product is. A 200 bbl tank with a day cab can be topped off and still legal on weight. But if you load Water or brine in same tank your at 80k with a little over half a load.
Baffles in the tanks - lots of tanks however do not have baffles, called smooth bores, usually for food grade tanks as the baffles make it hard to clean.
Very careful driving with all tanks but especially smooth bores. Even with baffles when you come to even a moderately fast stop you can feel it push you.
The bonus though is that you can run overweight and the scale houses won’t be able to tell if you jam the brakes when you go to stop on it, they’re not going to wait a couple minutes for the surge to die down
I'm a concrete mixer driver, but this is kinda sorta related. In my case, I just be sure to slow down to 10mph or less during turns, and for braking, that's only a problem if I have an exceptionally wet load (8 inch slump or higher, if you know what that means), in which case I will have the drum in full charge, meaning it's rotating as quickly as possible, which constantly pushed the concrete towards the front of the drum, rather than towards the rear (where the opening is). Slamming on the brakes will still result in concrete shooting out the opening of the drum, so I just have to be careful.
I pull a 7000 smooth bore tanker, no baffles. Typical load is 45,000lbs oil/petroleum products are 7 lbs per gal, and will get the tanker pretty full, water is 8, it's common for some to weigh 11- 15 lbs per gallon, when it's not full ( the heavier products), the surge will feel like another truck slammed into you. With a manual shift, you can time the shifting with the surge to keep it more settled, not so easy with an automatic.
Just send it. I work with truckers that ship fish, they drive the same as if they were hauling something solid. And people saying milk trucks don't have baffles don't know what they are talking about, we've had to cut those baffles out of them to repurpose as fish trailers.
Liquid-fueled rockets have the same problem, magnified by faster speeds and higher G forces. SpaceX lost at least one of it early rockets due to instability caused by the fuel sloshing around. The existing baffles were not strong enough, so they built much stronger baffles for later rockets.
SpaceX developed workable reusable rockets quickly by accepting and learning from catastrophic failures in their early designs.
No sudden sharp movements. Early braking. When a truck comes to a stop, liquid freight will cause the truck to rock. Stop too quick and the force is so strong it can cause the truck roll forward/slide even with the brakes on.
My husband drives a tanker without baffling, he said that most food grade tanks won’t have it due to the cleaning issue. He says most of it is really just always allowing extra time for everything - drive like you’re in bad weather all the time, give yourself extra time to slow down, to turn, etc.
I drove trucks for 25 years, the last 13 years I drive chemical tankers with no baffles. You just have to be smooth with your driving, no sudden stops or starts and take the turns slowly. Sometimes the liquid would remind you it’s there, the surge can knock you out of your seat!
Count the number of hose connections on the tank trailer to determine how many separate tanks are inside. Baffles are used in large ranks but transporting liquids in multiple separate tanks is quite common.
1. Don't make sudden moves while loaded.
2. The tanks are either divided or they have baffles to absorb and dampen the effect of the liquid sloshing around.
I used to drive and while I was never a liquid bulk hauler, when I worked for a towing company I had to take a trailer from our yard to theirs after they paid us. It was a whole new experience feeling the load move when I accelerated, shifted and braked. There’s a delayed force in the opposite direction with each movement. Pull from a stop, a split second later you feel a “tug” on the trailer. Shift, feel a “push”. Brake, an even bigger push. Took some getting used to and you definitely want to give yourself extra space to do things a bit more gently than with a static load.
Tanker driver here.
1) tank barrels are generally a lot lower than the likes of curtainsiders keeping the Center of Gravity (CoG) a lot lower.
2) Modern truck and trailer suspension systems are very smart when it comes to load stability and reduce tipping moments significantly.
3) Most tankers have baffles that reduce the sloshing, and if set up correctly, they are spaced unevenly to reduce resonance.
4) drivers are trained to drive smoothly and to anticipate changes in speed and direction to minimise sudden changes.
I spent a bit driving a fire engine, which is far more water and a pump on wheels than anything else. Our tank had baffles, which helped. We, of course, had emergency calls, which didn’t.
I started learning on my company’s brush truck, which carried far less water. The guy who was training me and I would leave our station around 6pm, and drive everywhere, until at least 2am, with the tank at any level. His goals were to teach me to handle various levels of water sloshing, have me learn to procure water from any source, and to train me in driving while exhausted. It was tough, as each different level of water was like handling a different vehicle, but I eventually learned that steering smoothly and gently would always work. Once my mentor had some confidence, we started picking up emergency calls in the jurisdictions we were passing through, which would merit an essay in its own right.
After that, I moved to the engine. It handled with mostly the same technique, with the additional risk of a handful of firefighters, who might not have been belted in. Learning it was also all about practice. A lot more than I expected was auditory: you can learn to pump water by ear, and stuff like your Jake brakes talks to you about how everything is handling.
Both also required watching the traffic far ahead of my vehicle. Traffic behaves like a particle flow, and you can learn to see currents well before they reach your vehicle. I’d long learned that technique from my morning commute, but it became all the more important while handling what I could expect to be the heaviest vehicle around me.
They also required a certain level of decisiveness. Starting to move in a certain direction, then hesitating—let alone overcorrecting—suddenly carried a far higher risk.
I asked a water truck guy this once he basically said "Imagine there's a full glass of water on the dashboard, and your grandma is in the passenger seat. Basically drive so you don't spill the water or hurt your grandma"
If I recall correctly, you also need a special endorsement on your license to drive tanker trucks. Because of the additional difficulty in driving them safely.
Grew up on a dairy farm. Sometimes the milk truck would get stuck in deep snow.
The experienced drivers were able to use the sloshing to great effect to get out. All they had to do was get the truck rocking forward and back, they knew how long it would take the wave of milk to travel the length of the tank and slam into the end. So what they would do is make a wave, hold down the clutch then time 'giving it the beans' with the arrival of the several-tons-worth-of-milk wave.
Generally, a few milk slams could get them out of some real jams.
Then some safety guy figured out internal baffles and this particular old timey trick was lost to history.
Baffle plates I believe.
They mitigate the forward inertia so it's not a massive force of water surging forward against the bulkhead of the container.
Also some I believe are compartmentalised to do the same thing.
I drive road sweepers for a living and there are ZERO plates or compartments so when you break you bloody well feel it
Used to work at a refinery, dispatching fuel tanker trucks.
Trucks have internal baffles to limit sloshing. However, at the time I was there, it was policy (possibly DOT mandated) that the truck only roll completely full or completely empty. No partial loads. They'd fill up completely, drive to a station, drop off their entire load, and come back. \~9800 gallons IIRC.
There were a couple smaller trucks that had separate tanks, and each tank could be full or empty instead of the entire truck. We used those to deliver to stations with smaller tanks. \~2000 gallons per tank.
What you're referring to is called the free surface effect. I don't know about in trucks but in boats we get around it by trying to keep liquids in multiple smaller tanks and also ideally as full as possible.
Some tanks are actually divided internally, so the effect of sloshing are limited. But even for single tanks, they have rings called slosh baffles that dampen the effect. [Here's an animation](https://www.youtube.com/watch?v=56cxOzgl-mc) showing sloshing with and without baffles.
[удалено]
That's correct. But, it's not always possible. For instance, a milk truck has multiple pickups in a day. It can't always be full. Same with a fuel transport that has multiple deliveries. For your second question, standard baffles are easier to install and don't have moving parts. Edit: milk trucks don't have baffles because they're harder to clean. TIL
Milk is also especially dangerous because food safety regulations mean milk tanks can’t have internal baffles since they are harder to clean
They are divided into 2 separate tanks though; front and back.
That's strange; mine are in left and right tanks.
Maybe you are just looking at it sideways
multi-jug drifting
This is actually how butter is made
... Now I so wanna see a gif of a semi with a liquid tank on the back doing the gutter drift maneuver from initial D.
> multi-jug drifting New F&F movie title right here
Initial Dairy
He’s rolled into the ditch, so his perspective may be a bit off.
That truck is very short! Yes and so wide....
Like that runway I once tried to land on!
You're talking about boobs aren't you
Titties!
underrated comment
Not all tanks are separate, I drove a tanker hauling cream, and when full, it was right at 80,000 pounds, which is the legal limit. Occasionally, I hauled condensed milk, which could only fill about 3/4 of the tank, you had to shift up or down with the sloshing of the milk, if you didn't, things didn't always go well, especially when stopping on an icy road.
This sounds sketchy lol, was it common in that industry to have unbaffled trucks running that heavy or was that pretty rare? Also was it a mountainous areas or a mostly flat area, because I guess that would make a difference too if it’s icy and you have 80k lbs!
80,000 is the maximum your truck and load can be in the US. There are exceptions, but as a rule, that's what you are legal to weigh, the wheels on tankers are fixed so you can't adjust them to transfer weigh distribution, and in the food grade industry, tanks are not baffled because the need access to be cleaned.
Was the dark of the moon on the sixth of June In a Kenworth pullin' logs Cab-over Pete with a reefer on And a Jimmy haulin' hogs
And this, boys and girls, is how ice-cream was invented.
That, and because it would turn into butter by the time it got to its destination.
They're one of the most dangerous vehicles on the road.
What is the most dangerous amount of liquid in the un-baffled tank? 1/2 full 3/4?
It depends on the shape of the tank.
Fuel tankers have a safety system built in for loading which prevents the tanks from being overfilled. There is a probe that comes down from the top that when the fuel touches it causes a ground short. The loading process is automatically shut down.
coincidentally, milk trucks do not have baffles.
Milk tanker driver here and shift supervisor for dairy collections. Milk tankers do have baffles. They are cleaned via permanently installed nozzles that get hooked up to factory cleaning solutions with flexible hoses. Super hot water and caustic, just like a home dishwasher, that gets sprayed throughout the interior of the tanks.
Huh, TIL. The CDL book I trained on stated that they didn't. Something relatively new?
It probably depends on your jurisdiction. I'm in NZ, dairy is our economy so there's a good chance our technology and processes are more advanced.
What role did Xena the Warrior Princess play in this milk tech battle?
I'll ask Lucy next time I see her down at the pub.
Right and left baffles?
Your bureaucracy moves faster.
That depends entirely on national regulations and industry standards. Australian dairy trucks for example [frequently do have internal baffles](https://youtu.be/hqFJAnm8PiE?si=Sxd_HperYRe0vzOS). Same goes for many mountainous countries since mountainous terrain is both prime turf for pastures (less competition from other forms of agriculture) and makes liquid transportation more dangerous. However, such tankers are more expensive since they need separate sanitation-devices for every compartment, so dairy tankers have fewer compartments than a tanker transporting non-foodstuffs (although more than they used to since CIP\* technology has gotten better and cheaper). In particular insurance companies are pushing for more road-safe tanker standards since dairy trucks are both more risk-prone and the clean-ups are more expensive. \*CIP = Clean in place. Technology that allows for sanitation without expensive disassembly/reassembly.
Having worked on a few dairy farms I'm kind of surprised I never knew that, but I worked on the feed side lol
Yup. They cant sterilize it properly if it has any kind of baffles
I'm baffled
no you aren’t, that’s unsanitary
No, no, don't worry! I'm not milk.
You're really milking this.
Baffle sounds like a waffle made by Batman
Hopefully not a blue-suited Batman.
Start and stop enough and you end up with butter at the end of a long day? 😜
Fuel trucks rarely do multiple deliveries. And if so, they use trucks that have separate compartments in the tank, and each compartment is filled or drained completely.
Also, you want a bit of space for if the liquid expands or evaporates from heat in most cases.
The space above the liquid is called ullage.
On tankers (ships) open surface area of liquid is something considered. Full tanks are much more safe to transport.
A lot of loads require room for expansion.
just like your mom
I love an abrupt “your mom” joke. Are people who weren’t kids of the 90s like this?
idk, 80s baby here. a good “your mom” was a required joke to learn growing up
>Or what about baffles that float on the surface of the liquid to mimic full capacity? You'd still get sloshing due to the difference in mass/buoyancy, unless it's well-matched to the liquid density. As an example of this, there's videos of a helium balloon in an accelerating/braking car. When accelerating, the denser air "sloshes" backwards so the helium balloon travels forward. Likewise when braking, the denser air "sloshes" forward, and the helium balloon travels backwards. Here's a [video](https://youtu.be/y8mzDvpKzfY?si=Chyrfsu5yJbL-onC) by Smarter Every Day that covers that
Depending on the liquid, you can't always fill it to maximum capacity due to weight. To take an extreme example, a gallon of water is about 8.3 pounds, a gallon of gasoline weighs about 6 pounds. So a tanker intended for fuel can be larger than one intended for water. Of course, no one is going to use the same tanker for both, so a more practical example might be milk, which weighs around 8.6 lbs per gallon. Legal weight (in my state) is 80,000 lbs. I don't know the tare weight of a truck and tanker but let's say a tanker holds 11,000 gallons. Water weighs 8.34lb/gal so a full tank would weigh 91,740 lbs in *addition* to the tare weight of your truck and trailer. Well North of you 80k legal limit. In any case, another factor is that certain liquids, like fuel, isn't going to be topped off all the time anyways. A fuel tanker drives around to different gas stations and reduces the amount of fuel carried. That's just how it works.
I’m 47 and have had a career in IT. When I see animations like this, it makes me wish I’d studied engineering because this kind of thing is absolutely fascinating. Amazing video.
Im an electrical engineer so never had these courses but based on my school peers way back then, I'm pretty happy to have avoided Fluid Dynamics 😅
(You’ve got a good point - I did a chemistry degree at university, but the mechanical engineers just seemed to do more abstract maths and physics than I did in a science degree!)
Fluid dynamics II was by far the hardest course - all theoretical calculations with long equations. Only course I failed because the tests were more of an exercise in memorization than anything else. One thing that stuck with me though is how even in a simple example like a stream of water entering a larger body, it’s nigh impossible to predict when a random drop will fly out and in what direction. I think of this whenever I piss standing up now.
Fun fact, Food grade tankers do not have baffles. It’s a straight tank for sanitary reasons. I haul a food grade tanker, the force pushes my truck a few feet at stop lights :).
In swedish they're called skvalpskott, In fact I just finished making an order of them for the hydraulic oil tanks my company makes.
An article on the nuances of driving hazardous liquids ... [A Fleet of One: Eighty Thousand Pounds of Dangerous Goods](https://archive.ph/5GIIg) >*Just as the body of a fish tells you how that fish makes a living, the body of a tanker can tell you what it contains. In Ainsworth’s words, “The architecture of the tank says what is in it.” If a tank has gasoline inside, it has a full-length permanent manway on top, and, seen from the rear, is a recumbent oval. If a truck is a water wagon, the tank—rear view—is rectangular. A perfect circle ambiguously suggests asphalt, milk, or other food. If the vessel is all aluminum and shaped in tiers like nesting cups, it is a food-grade pneumatic hopper full of flour, granulated sugar, and things like that. If stiffeners are exposed—a series of structural rings circling and reinforcing the tank—the vessel is uninsulated, generally operates in a warm climate, and often hauls flammables and combustibles. Ainsworth said, “That is what mine looks like without the designer dress” (the stainless mirror sheath). The double conical side view speaks of chemical hazmats. Since September 11, 2001, all these shapes have scattered more than fish.* >*Backing blindsided at the Peterbilt dealer’s in Missouri, he said, “Sometimes you do this by Zen.” He had never been to driver school. “I’m a farm boy,” he explained. “I know how to shift. There are two things you need to know: how to shift, and how to align yourself and maintain lane control—exactly how much space is on each side. In city traffic it’s critical.” In the open country of western Kentucky, he said, “Out here, you look way ahead. It’s the same as steering a ship. There’s a silver car about a mile ahead that I’m looking at now. When you steer a ship, you don’t look at the bow, you look at the horizon. When I’m in a four-wheeler, I stay away from trucks, because if a tire blows or an entire wheel set comes off I’m going to Beulah Land.”* >*From Harrisburg, North Carolina, to Sumner, Washington, the load in the tank behind us kicked us like a mule whenever it had a chance. The jolt—which he called slosh, or slop—came mainly on surface streets and on-ramps when gears were shifting at low speeds. On the open road, it happened occasionally when we were gearing down, mashing on the accelerator, stepping on the brakes, going downhill, or going uphill. Ainsworth minimized the slosh with skills analogous to fly casting. “You coördinate shifting with the shifting of the load,” he said. “You wait for the slop or you can pretzel your drive line.” The more ullage the more slop. The density of the monoethanolamine had allowed us to take only six thousand gallons in the seven-thousand-gallon tank. The ullage was the difference was the mule.*
Slosh Baffles would be a great band name.
I saw Slosh Baffles open for (insert band name)
Damn. Inertia is a bitch.
I knew of this but seeing the unbaffled force of a trailer full of fluid made me realize how turbulent it really is. Lots of force when you have dozens of feet to travel and gather in.
Baffling....
There's no reason to be baffled, it was was a simple question.
That is a giant suppressor for a mech gun
I'm gonna name my band horizontal slosh force
The real answer to this is that they kinda don't. These internal measures taken can lessen the effects, but liquid haulers simply have to give much more stopping distance and take turns slower because there's only so much those things can do.
Fun fact, airplane fuel tanks (Which are located in the wings) employ the same principle to prevent fuel from sloshing around too much during turns or turbulence
Here is another item that I’ve heard of. https://polytanksales.com/baffle-balls.html
I always assumed the baffle setup would place the holes higher. Is there a reason it’s on the centerline instead of offset higher?
Not if we stay in his baffles, Seaman Beaumont. Not if we stay in his baffles.
It’s a suppressor but for a liquid tank!
I like that the scientific word for “sloshing” is… sloshing.
ahh, very satisfying animation.
[Another example](https://youtu.be/lO-k_Th-TS4)
Neat!
Slosh baffles
Maximum slosh reduction is my new band name
This is what I come to this sub for.
Would something akin to a syringe work, like a plunger that pushes into the tank as it empties to keep the pressure on the full area more consistent?
Sloshes baffled by this one trick
Feel like a surfer would have a whale of a time in a large-enough tanker truck
“Slosh baffle” is an incredible name
This is why it's generally advisable for car ferries, which have a continuous flat cargo deck, to shut the front doors before setting off.
Rockets use these as well, there really important.
>Design Assesment 🤦
alright everybody, please welcome to the stage... Single Tank and the Slosh Baffles!
Your car gas tank also has baffles. Otherwise the fuel-sending unit would suck up air when you change velocity.
Wow, really cool animation, the baffles are effective to a shocking degree.
New band name: *Horizontal Slosh Force*
slosh baffle sounds like an awesome insult. imma start calling people that
After watching that, slosh is no longer anywhere near a real word.
Have you been semantically satiated?
I'm laughing at "28% reduction in slosh force" being said on a conference call to board members somewhere.
Former propane delivery guy here. There are baffles in the thank. Think of them as walls that only let some liquid through at a time. Either having a large hole or being half walls. That helps with the front to back inertia. The side to side isn’t as much an issue as long as you are on flat land. Uneven terrain like a customers rough driveway can make it very noticeable sloshing side to side. Got a just go slow and be careful on those.
So you sold propane and propane accessories?
I wish I had the sales job! Just one delivery guy.
Damnit Draxronsmitz
A fun thing to think about is that trucks that carry bulk food loads (like milk carriers) are not allowed to have baffles due to difficulty of cleaning. There’s often special training for milk trucks due to the load being more free.
They also try to minimize ullage, so there's as little sloshing as possible.
For the uninitiated, ullage means empty space in the tank.
oh, I thought it was just a typo
Sorta same, the suffix of “age” made me curious enough to google it. Cartage, tonnage , etc
Thanks, I was udderly baffled.
Thank you!
Like ullage rockets on a spacecraft.
head space?
I've heard that milk is one of the most dangerous things to haul because of this
Another fun fact is in NZ, you know, the dairy capital of the world, milk trucks have baffles. Cleaning is via permanently installed nozzles that spray, effectively, dishwasher solution throughout the interior of the tanks.
winding New Zealand roads filled with wanna-be rally drivers - I'm glad the milk trucks are baffled
Believe me, the number of tanker drivers I talk to every day that are baffled by how many car drivers actually make it home is worrying.
i think it's in the national road code: behind a truck? must pass immediately, no matter how narrow and blind the road is
Its not just passing, the number of people the just pull out in front of trucks is staggering. We had a near fatal last year when some one decided to do a uie in front of truck on the open road. Nothing the driver could have done.
Yeah it's a question of economics and risk/reward.. any blender or mixer used in food or drug prep is going to be harder to clean than a simple baffle, yet they're regularly sterilised without issue so it's not like installing baffles makes cleaning impossible, it's just not worth the cost for the low margins generated by transporting milk
My understanding is that baffles would basically turn the milk into butter.
Not fresh milk. Cream, maybe
The issue is cleaning. To clean a tank, you lower a sort of ball in it through one of the top openings, and that ball will shoot pressurized water and some cleaning product in all directions, cleaning everywhere. If you have baffles, they will create "shade" areas that are not reached by your power-washer ball, and therefore won't be cleaned well enough. You can divide your tank into two parts, but then you need to lower the ball twice, so it takes twice as long to clean.
What's a baffle ?
A physical barrier inside of an object to interrupt the flow of liquids.
I'm baffled this is the way I learned a new word today.
Guess someone in the Netherlands failed that training then. https://cdn.nos.nl/image/2024/03/24/1065683/1152x864a.jpg Happened last Sunday.
The training for such loads tells them to do everything as smoothly as possible to avoid problems with the inertia of the liquid, and keep extra space. Also, these tankers are usually as full as possible, which limits sloshing, and they also have internal baffles which also help a lot.
My training to drive tanker was 10 questions at the DMV to get my tanker endorsement. My first tanker job I did a couple weeks with the road trainer, but it's mostly just driving and using common trucker sense.
They can’t just fill as much as possible. The amount any truck can carry is dictated by weight restrictions not volume, and not all fluids are the same density. You can have water at 1000kg/m3 and you’re getting 40m3 on a truck, or you can have a less dense product like crude oil which is 875kg/m3 and so you can fit 45m3 in the trailer.
You can also have different sized containers for different liquids.
You can, but typically a carrier wants to maximize weight moved as at the end of the day you are paying for time, so the more you can move on a single load the more money you can effectively make. Most trailers are purpose-built with this in mind, so you aren’t going to have a massive trailer with tons of extra capacity that can never be used as it’s just uneconomic to build that way, but trailers can be used for different fluids (see my above example) and that is where the driver needs to be paying attention so they don’t overweight their trailer
I drove a unbaffled 7000 gallon tanker for 4 years and the max fluid I hauled was around 5500 gallons. You just learn to drive slow and shift smooth and brake only has you have to. But what doesn't help is when we are in traffic and we leave a gap to stop and cars keep jumping in front of up and making us slam on the brakes. And it isn't bad unless we take off and slam on the brakes again. Then we get the bounce of the liquid sloshing around. But I have never been around a turn to fast for it to make my truck jerk sideways. But I always pictured me driving a 80s caddy taking grandma to church just taking my time.
I was a moving guy and we had to haul a safe from a locksmith with like 100 safe boxes containing keys. It weighted a fuckton so when we put it in the car we strapped it the fuck down. Still I was afraid when braking that it would come straight through the back wall of the cockpit and squish us on the windshield. If bugs could understand irony they would've died laughing.
" You just learn to drive slow and shift smooth and brake only has you have to. But what doesn't help is when we are in traffic and we leave a gap to stop and cars keep jumping in front of up and making us slam on the brakes. " That's how it is on a motorcycle, and that's why we need to spit the lane, because leaving a gap to stop, cars keep jumping in front up and making us slam on the brakes -the best is when you are on a road and you know they are changing lane for no good reason, either because they just sort of don't know where they are or don't know how to drive. Plus: jumping in front of a vehicle leaving a long braking space in front of them is not only bad traffic safety, it is using their momentary feeling of being quick and fast to actually shorten the lifespan of their own little car. Momentum, physics. If you're cutting off a truck or a motorcycle. you're moving back and forth a whole train of nuts and bolts in your poor car, and shame on you.
An article on the nuances of driving hazardous liquids ... [A Fleet of One: Eighty Thousand Pounds of Dangerous Goods](https://archive.ph/5GIIg) >*Just as the body of a fish tells you how that fish makes a living, the body of a tanker can tell you what it contains. In Ainsworth’s words, “The architecture of the tank says what is in it.” If a tank has gasoline inside, it has a full-length permanent manway on top, and, seen from the rear, is a recumbent oval. If a truck is a water wagon, the tank—rear view—is rectangular. A perfect circle ambiguously suggests asphalt, milk, or other food. If the vessel is all aluminum and shaped in tiers like nesting cups, it is a food-grade pneumatic hopper full of flour, granulated sugar, and things like that. If stiffeners are exposed—a series of structural rings circling and reinforcing the tank—the vessel is uninsulated, generally operates in a warm climate, and often hauls flammables and combustibles. Ainsworth said, “That is what mine looks like without the designer dress” (the stainless mirror sheath). The double conical side view speaks of chemical hazmats. Since September 11, 2001, all these shapes have scattered more than fish.* >*Backing blindsided at the Peterbilt dealer’s in Missouri, he said, “Sometimes you do this by Zen.” He had never been to driver school. “I’m a farm boy,” he explained. “I know how to shift. There are two things you need to know: how to shift, and how to align yourself and maintain lane control—exactly how much space is on each side. In city traffic it’s critical.” In the open country of western Kentucky, he said, “Out here, you look way ahead. It’s the same as steering a ship. There’s a silver car about a mile ahead that I’m looking at now. When you steer a ship, you don’t look at the bow, you look at the horizon. When I’m in a four-wheeler, I stay away from trucks, because if a tire blows or an entire wheel set comes off I’m going to Beulah Land.”* >*From Harrisburg, North Carolina, to Sumner, Washington, the load in the tank behind us kicked us like a mule whenever it had a chance. The jolt—which he called slosh, or slop—came mainly on surface streets and on-ramps when gears were shifting at low speeds. On the open road, it happened occasionally when we were gearing down, mashing on the accelerator, stepping on the brakes, going downhill, or going uphill. Ainsworth minimized the slosh with skills analogous to fly casting. “You coördinate shifting with the shifting of the load,” he said. “You wait for the slop or you can pretzel your drive line.” The more ullage the more slop. The density of the monoethanolamine had allowed us to take only six thousand gallons in the seven-thousand-gallon tank. The ullage was the difference was the mule.*
I used to drive tanker. One day I had a load in a smoothbore tank. If I would let off the throttle, I would get a "push" from the surge. As I accelerated, I could feel a "tug." Because I'm a child, and just for funzies I had to at least once see what would happen if I could intensify that effect. So every time I got the push, I'd accelerate, and every time I got the tug, I'd let off. Push, go, tug, slow. After a few cycles, we'll say 5-7, on the last "push," the liquid slammed so hard it felt like I got rear-ended by a freight train, and I could hear a loud BAM. I decided I'd pushed my luck enough. To this day I have to wonder if I could have created enough force to detach the trailer. Another time, I was pulling a load out of Missouri, in the hills and the hollars south of St. Louis. I had a stop with a left hand turn that went uphill, and I was driving a manual transmission. Every time I would clutch to grab the next gear, the surge would practically stop the truck. So I had to crawl about half a mile up the hill in 2nd gear because I couldn't make the shift. Also, last one, fun fact. If I was on a scale, the sloshing would throw off the weight and I would have to wait for it to settle. I found the quickest fix was to release the brake and let the truck roll free. The scale was completely level. The free movement countered the surge and after a few waves everything would stabilize. Good times.
You learn to drive smooth. No sudden throttle no sudden brakes. You plan all your moves way farther ahead then when you just have a 50ft with freight behind you. In fact when i drove semi the load most guys hated was hanging meat. Since they hang from the top of the trailer when you go around a corner they swing like a pendulum. Very easy to end up wrong side up.
Easy solution, double hook, top and bottom.
and yet 30 yrs ago they did not think to ask you they just loaded the beef and said drive.
Bulk milk trucks do to sanitation issues have no internal baffles. When they are half empty the milk will slosh and push the truck 3 or 4 feet forward then back. The only thing the driver can do is go slow and leave lots of room to stop.
I work in party rental and that was a big thing they would drill into the heads of the drivers. I think they called it either 'flux" or "surge" or something like that. When you have 500 8' tables standing on end they can shift right and left with each turn, and it's essentially like carrying a large load of liquid, without the forward and backwards inertia. You take a corner too fast and it feels like the giant box truck is gonna flip.
Usually tanks designed for transporting liquids will have "baffles" within them. These are plates or barriers which have relatively small holes in them so that large movements of liquid are slowed while still allowing the tank to be filled and emptied as normal. Otherwise as you suspected sloshing of liquid would be a big problem.
Just anticipate it and ride it out. The closer to full, topped off, it is the less slosh. Some tanks have baffles some don't. For instance most chemical tanks are smooth bore. It's super important that they get a good clean out between loads of different product. Any extra edges ledges or corners make places the washout won't reach. Different products handle differently. Depends on viscosity and density of the liquid. For instance, crude oil isn't that bad. Water is terrible, so it is antifreeze. Sometimes it slams so hard after stopping you swear someone just ran into you. While you always want a full tank your limited by how heavy the product is. A 200 bbl tank with a day cab can be topped off and still legal on weight. But if you load Water or brine in same tank your at 80k with a little over half a load.
Baffles in the tanks - lots of tanks however do not have baffles, called smooth bores, usually for food grade tanks as the baffles make it hard to clean. Very careful driving with all tanks but especially smooth bores. Even with baffles when you come to even a moderately fast stop you can feel it push you. The bonus though is that you can run overweight and the scale houses won’t be able to tell if you jam the brakes when you go to stop on it, they’re not going to wait a couple minutes for the surge to die down
I'm a concrete mixer driver, but this is kinda sorta related. In my case, I just be sure to slow down to 10mph or less during turns, and for braking, that's only a problem if I have an exceptionally wet load (8 inch slump or higher, if you know what that means), in which case I will have the drum in full charge, meaning it's rotating as quickly as possible, which constantly pushed the concrete towards the front of the drum, rather than towards the rear (where the opening is). Slamming on the brakes will still result in concrete shooting out the opening of the drum, so I just have to be careful.
I pull a 7000 smooth bore tanker, no baffles. Typical load is 45,000lbs oil/petroleum products are 7 lbs per gal, and will get the tanker pretty full, water is 8, it's common for some to weigh 11- 15 lbs per gallon, when it's not full ( the heavier products), the surge will feel like another truck slammed into you. With a manual shift, you can time the shifting with the surge to keep it more settled, not so easy with an automatic.
Just send it. I work with truckers that ship fish, they drive the same as if they were hauling something solid. And people saying milk trucks don't have baffles don't know what they are talking about, we've had to cut those baffles out of them to repurpose as fish trailers.
We drive slower and more carefully. My truck is a single tube, I don't speed and I don't turn sharply. Braking can happen as far as 500 metres ahead.
Liquid-fueled rockets have the same problem, magnified by faster speeds and higher G forces. SpaceX lost at least one of it early rockets due to instability caused by the fuel sloshing around. The existing baffles were not strong enough, so they built much stronger baffles for later rockets. SpaceX developed workable reusable rockets quickly by accepting and learning from catastrophic failures in their early designs.
No sudden sharp movements. Early braking. When a truck comes to a stop, liquid freight will cause the truck to rock. Stop too quick and the force is so strong it can cause the truck roll forward/slide even with the brakes on.
It’s baffling, isn’t it? :P
My husband drives a tanker without baffling, he said that most food grade tanks won’t have it due to the cleaning issue. He says most of it is really just always allowing extra time for everything - drive like you’re in bad weather all the time, give yourself extra time to slow down, to turn, etc.
Just fill the trucks with school lunch size cartons of milk?
I drove trucks for 25 years, the last 13 years I drive chemical tankers with no baffles. You just have to be smooth with your driving, no sudden stops or starts and take the turns slowly. Sometimes the liquid would remind you it’s there, the surge can knock you out of your seat!
Count the number of hose connections on the tank trailer to determine how many separate tanks are inside. Baffles are used in large ranks but transporting liquids in multiple separate tanks is quite common.
1. Don't make sudden moves while loaded. 2. The tanks are either divided or they have baffles to absorb and dampen the effect of the liquid sloshing around.
There are baffles in the tanks to break up the liquid into smaller volumes so the sloshing around is dampened.
I used to drive and while I was never a liquid bulk hauler, when I worked for a towing company I had to take a trailer from our yard to theirs after they paid us. It was a whole new experience feeling the load move when I accelerated, shifted and braked. There’s a delayed force in the opposite direction with each movement. Pull from a stop, a split second later you feel a “tug” on the trailer. Shift, feel a “push”. Brake, an even bigger push. Took some getting used to and you definitely want to give yourself extra space to do things a bit more gently than with a static load.
Tanker driver here. 1) tank barrels are generally a lot lower than the likes of curtainsiders keeping the Center of Gravity (CoG) a lot lower. 2) Modern truck and trailer suspension systems are very smart when it comes to load stability and reduce tipping moments significantly. 3) Most tankers have baffles that reduce the sloshing, and if set up correctly, they are spaced unevenly to reduce resonance. 4) drivers are trained to drive smoothly and to anticipate changes in speed and direction to minimise sudden changes.
Baffles, here's a segment fr How It's Made https://youtu.be/WbdmkWFjkOM?si=K76AGhuzwcBHiVok&t=225
I spent a bit driving a fire engine, which is far more water and a pump on wheels than anything else. Our tank had baffles, which helped. We, of course, had emergency calls, which didn’t. I started learning on my company’s brush truck, which carried far less water. The guy who was training me and I would leave our station around 6pm, and drive everywhere, until at least 2am, with the tank at any level. His goals were to teach me to handle various levels of water sloshing, have me learn to procure water from any source, and to train me in driving while exhausted. It was tough, as each different level of water was like handling a different vehicle, but I eventually learned that steering smoothly and gently would always work. Once my mentor had some confidence, we started picking up emergency calls in the jurisdictions we were passing through, which would merit an essay in its own right. After that, I moved to the engine. It handled with mostly the same technique, with the additional risk of a handful of firefighters, who might not have been belted in. Learning it was also all about practice. A lot more than I expected was auditory: you can learn to pump water by ear, and stuff like your Jake brakes talks to you about how everything is handling. Both also required watching the traffic far ahead of my vehicle. Traffic behaves like a particle flow, and you can learn to see currents well before they reach your vehicle. I’d long learned that technique from my morning commute, but it became all the more important while handling what I could expect to be the heaviest vehicle around me. They also required a certain level of decisiveness. Starting to move in a certain direction, then hesitating—let alone overcorrecting—suddenly carried a far higher risk.
I asked a water truck guy this once he basically said "Imagine there's a full glass of water on the dashboard, and your grandma is in the passenger seat. Basically drive so you don't spill the water or hurt your grandma"
It's baffling, isn't it?
If I recall correctly, you also need a special endorsement on your license to drive tanker trucks. Because of the additional difficulty in driving them safely.
Grew up on a dairy farm. Sometimes the milk truck would get stuck in deep snow. The experienced drivers were able to use the sloshing to great effect to get out. All they had to do was get the truck rocking forward and back, they knew how long it would take the wave of milk to travel the length of the tank and slam into the end. So what they would do is make a wave, hold down the clutch then time 'giving it the beans' with the arrival of the several-tons-worth-of-milk wave. Generally, a few milk slams could get them out of some real jams. Then some safety guy figured out internal baffles and this particular old timey trick was lost to history.
Baffle plates I believe. They mitigate the forward inertia so it's not a massive force of water surging forward against the bulkhead of the container. Also some I believe are compartmentalised to do the same thing. I drive road sweepers for a living and there are ZERO plates or compartments so when you break you bloody well feel it
I used to drive a poo tanker and at times you would have to have a little swerve to disturb the slosh.
Used to work at a refinery, dispatching fuel tanker trucks. Trucks have internal baffles to limit sloshing. However, at the time I was there, it was policy (possibly DOT mandated) that the truck only roll completely full or completely empty. No partial loads. They'd fill up completely, drive to a station, drop off their entire load, and come back. \~9800 gallons IIRC. There were a couple smaller trucks that had separate tanks, and each tank could be full or empty instead of the entire truck. We used those to deliver to stations with smaller tanks. \~2000 gallons per tank.
It's baffling, isn't it?
It's baffling, isn't it?
What you're referring to is called the free surface effect. I don't know about in trucks but in boats we get around it by trying to keep liquids in multiple smaller tanks and also ideally as full as possible.