Tanker driver question

Figure that a pressurized tank contains a considerable volume of compressed [N2 in this case] air/gas and you are relieving all that capacity through a 1/2 inch hole. It takes a few minutes.

Possibly the unloader is shutting your trailer down as soon as the hose starts to jump indicating that just air is moving through the hose.. Some places let the trailer blow their lines out a bit before shutting things off leaving less pressure [hence less volume of compressed stuff to evacuate] for a shorter blow down.

Other places have vent issues, etc. and shut right down immediately said the driver trainer chewed out for burping a latex tank onto the ceiling. Durn 3" hose passed thru a wall and it didn't really jump when it blew empty.

 

We used to purge transformer oil trailers with N2 o make sure they were dry for loading. Had to label them every time.

Plant air compressor crapped out. Boss talked them into a sul air screw compressor with desiccant unit. and we bought a digital hydrometer and blew dry air until the dew point measured -20 degrees. No more N2 and no more labels

 

Your BOL satisfies the DOT requirement.

 

Several things,,
First, if you have a nitrogen blanket, you have either a flammable product or a product that degrades with air contact.
2.. if you are unloaded do not depressurize unless told to by your company!
3. Most important. LABLE ALL PAPERWORK THAT TANK HAS A NITROGEN ATMOSPHERE!!!!!
AND YOU NOTIFY THE TANKWASH PERSONNEL.
4. Nitrogen does not make your trailer lighter.

 

I drive with a pressurized tank all the time. One of our customers requires the tank to have between 5-10 psi upon loading. It all depends on the customer. It’s not illegal to move a pressurized trailer

 

One other thing, even if you depressurize the tank, the atmosphere in that tank is still deadly. The tank has to be open and vented before all the nitrogen is removed.

 

It's possible, depending upon the concentration of the flammable vapor.