Pumps. Pneumatic versus vac pump

Vacuum pump is for liquid and pneumatic is for dry products like sugar sand or flower

 

I'm not a mechanic or an expert but I have run both kinds. Pnuematics use a air blower, extremely similar to a supercharger that you see on gas engines in cars. (Roots type blower) while a vacuum pump is used for liquids. Different tools for different jobs.

 

Think of it like trying to suck or blow a bag of flower through a straw. It won't work until you blow a bunch of air into it, and can suck the air and some flower at the same time. Fluids don't have the same problem.

 

Blowers usually discharge into the trailer but can be set up, with a self loading trailer, to suck on the filter housing creating a vacuum in the trailer that lets you suck in the product.some have a dedicated hookup while others have to open the air filter canister to hook up the 4' vac line [discharge blower line is 3"]

Wet vacuums are usually hard piped and have a 4-way valve that allows you to switch from suction to discharge by just turning the valve.