To help you understand why some Tanker Trailers have Baffles/ bulkheads and others do not?
I like to introduce you to something some call Liquid Surge or others “The sloshing effect” In Tanker Trailers.
The sloshing effect results from the movement of the liquid in partially filled tanks. This movement can have bad effects on handling. For example, when coming to a stop, the liquid will surge back and forth. When the wave hits the end of the tank, it tends to push the truck in the direction the wave is moving. If the truck is on a slippery surface such as ice, the wave can shove a stopped truck out into an intersection. The driver of a liquid tanker must be very familiar with the handling of the vehicle.
However, in a tanker without baffles (sometimes called “smooth bore” tanks), where there’s just one liquid product, it’s a completely different story. A tanker without baffles handles differently than any other trailer. have nothing inside to slow down the flow of the liquid. Therefore, forward-and-back surge is very strong. non-baffled tanks are usually those that transport food products (e.g., milk). (Most sanitation regulations forbid the use of baffles because of the difficulty in cleaning the inside of the tank.)
Sources: truckingtruth.com , smart-trucking.com