8.2 – Driving Tank Vehicles

Liquid surge results from:

• The tanker being overloaded on the trailer axles
• The tanker being overloaded on the drive axles
• The movement of the liquid in a tank that is completely full
• The movement of the liquid in partially filled tanks.

Some liquid tanks are divided into several smaller tanks by:

• Dykes
• Mastheads
• Luvers
• Bulkeads

Some liquid tanks have bulkheads in them with holes that let the liquid flow through. What are these called, and what do they do?

• They are called centuries and they help prevent pressure from building up in the tank
• They are called baffles and they help to control the forward and backward liquid surge.
• They are called mastheads and they help prevent the sides of the tank from getting crushed inward
• None of these are correct

Liquid surge results from the movement of the liquid in partially filled tanks. What are some characteristics of liquid surge?

• All these are correct
• When coming to a stop, the liquid will surge back and forth
• When the wave hits the end of the tank, it pushes 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

What have tests shown about tankers, and how should you manage it?

• Tankers can turn over at the speed limits posted for curves. Take highway curves and on-ramp/off-ramp curves well below the posted speeds.
• Tankers will be more likely to turn over if the center of gravity is low. Keep the center of gravity high when loading a tanker.
• Tankers will not turn over if you follow the posted speed limit signs in curves. Always stay at the posted speed limit for any curve
• Stopping distance will decrease as the liquid sloshes forward. Press the brakes with more of a "stabbing" motion to quickly slow the vehicle.

The amount of liquid that can be loaded into a tank depends on:

• The amount the liquid will expand in transit.
• All these are correct
• The weight of the liquid.
• Legal weight limits

Describe unbaffled liquid tankers:

• They are sometimes called “lockhead” tanks and they have completely separate tanks within the main tank to divide up the liquid
• They are sometimes called “masthead” tanks and they have wires inside to slow down the flow of the liquid from side to side.
• They are sometimes called “smooth bore” tanks and they have nothing inside to slow down the flow of the liquid. Therefore, the forward-and-back surge is very strong.
• They are sometimes called “rodding” tanks and they have mastheads inside to prevent the liquid from sloshing side to side

Never load a cargo tank totally full. Liquids expand as they warm and you must leave room for the expanding liquid. What is this extra room called?

• Compartmentalization
• Outage
• Drainage
• Seepage

High center of gravity means:

• Much of the load's weight is carried high up off the road. This makes the vehicle top-heavy and easy to roll over.
• That much of the load's weight is carried low down near the road. This makes the vehicle top-heavy and easy to roll over.
• Sloshing will decrease the height above the road that the weight of the liquid is centered
• Gravity will center its influence on the liquid closest to the frame of the tractor

What type of product do unbaffled tankers normally haul, and why?

• They transport food products (e.g., milk) because sanitation regulations forbid the use of baffles because of the difficulty in cleaning the inside of the tank.
• They transport chemicals to prevent the sloshing of the liquid from side to side
• They transport gasoline because they need to divide the tank into separate compartments for the different grades of gasoline
• They transport chemicals because of the special anti-corrosive properties of the unbaffled tanks

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