PTO wetline kits/air compressor questions

Yea ptos go on the side behind the fuel tanks.

 

Here's how my Quincy compressor is mounted.

 

I did some generic tanker training videos a while back, but I never recorded a pump load only an air off. Customers can get a little wierd about filming on their property. I was going to do a propane delivery video, but again no filming or even having a phone outside the truck, so I did a walk n talk around the trailer.

 

Most of the time we used customer air, with a regulator we would attach to their fitting, then hook the air hose up. Regulator looked sort of like this but pressures much lower:


One customer pad that we unloaded three different chemicals at had a regulator installed on their air line. Like this, but black (the round knob under the gauge adjusts the pressure setting):

One tractor I drove had a separate line (passenger side) that tapped off the tractor's air. Same as customer air, attached pressure regulator, hooked the airline and charged the trailer. Most chemical liquid loads (that I've done) didn't take that much air to push off.
Only time we used a PTO driven air pump was for pneumatic loads. Even then, that was to keep up with volume of air, pressure was not that much (14 psi max).