Pneumatic blower

Pneumatic blower: A pneumatic blower is the air compressor, usually driven by the truck's engine, that pressurizes a dry bulk trailer so the load flows out through a hose into a customer's silo. Cement, fly ash, flour, sugar, plastic pellets and frac sand are unloaded this way.

How it works

The blower pushes air into the sealed trailer. Air fluidizes the powder or pellets in the hoppers, and the pressure drives the product through the discharge line and up into the silo. The driver controls the air and the product valves to keep a steady flow without plugging the line. When the trailer is empty, the pressure is bled off before any hatch is opened.

Safety and care

• Never open a hatch or fitting while the trailer is pressurized.
• Check the pressure relief valve and gauges before each unload.
• Keep filters clean; a dusty blower wears out fast.
• Food-grade products need clean, dedicated trailers and wash records.

In practice EXAMPLE

A driver delivers cement to a ready-mix plant. They connect the hose to the silo inlet, start the blower with the PTO engaged, bring the trailer up to pressure and open the first hopper's product valve. When the hopper empties, they move to the next. After the last one, they let the pressure drop to zero before disconnecting. Dry bulk loads are dense, so check payload with the weight limit checker. More in pneumatic trailers.

Unload times and pricing

A pneumatic unload takes time, often an hour or more depending on the product, the line length and the height of the silo. Dense products like cement move differently from light ones like flour. Carriers count unload time when pricing loads and look for detention terms on the rate confirmation for slow sites. Long hose runs and high silos slow the unload and work the blower harder, so ask about the site before you accept the load.

Blowers run hot and loud. Wear hearing protection near a running blower, keep hands clear of belts and couplings, and let the unit cool before touching it. A worn blower takes longer on every unload, so service it on the maker's schedule and keep a spare belt in the truck.