The N endorsement: liquid surge, baffles and tank handling. You need 80% correct to pass (49 CFR 383.135).
The tank vehicle test earns the N endorsement, needed to haul liquids or gases in tanks above a federal size threshold, whether or not the cargo is hazardous. It covers liquid surge, baffles, outage, rollover and tanker inspection. It is a knowledge test, and 80 percent correct is passing.
Last checked against the handbook and 49 CFR on .
| Tank setup | Tank vehicle? |
|---|---|
| One 900-gallon tank | No, total is under 1,000 gallons |
| Two tanks of 500 and 600 gallons | Yes, each is over 119 gallons and the total is 1,100 |
| Ten 100-gallon drums | No, no single tank is over 119 gallons |
| Empty 1,000-gallon container strapped to a flatbed | No, the empty-container exception applies |
| Situation | What to do |
|---|---|
| Curves and ramps | Slow down well before them, since posted speeds may be too high for a tanker |
| Starting and stopping | Be smooth and brake early with steady pressure |
| Emergency stop | Use controlled braking or stab braking, and avoid quick steering |
| Wet road | Allow roughly double the normal stopping distance |
| Empty tank | Stopping may take longer than when full |
| Skid on a tank trailer | Restore traction fast or the rig may jackknife |
A tank vehicle has tanks that each hold over 119 gallons and together hold 1,000 gallons or more. Meeting only one of those two tests does not make it a tank vehicle. 49 CFR 383.5
Yes, if the tanks meet the size definition. The liquid or gas does not have to be hazardous material for the N endorsement to apply. CDL Handbook 8.1
Outage is the space deliberately left empty in a cargo tank so the liquid can expand as it warms. Never fill a tank completely, and learn the outage needed for each product you haul. CDL Handbook 8.2
Baffles are partitions with openings that slow the liquid surging forward and backward. They do not stop side-to-side sloshing, so you still need slow, smooth driving to avoid a rollover. CDL Handbook 8.2
Only if you hold the N endorsement on the permit, and the tank must be empty. A permit holder may not drive any tank vehicle that has carried hazardous materials unless it has been purged of residue. 49 CFR 383.25
New to the CDL? Read how to get a CDL, which endorsements you need and the pre-trip inspection checklist.
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