Mechanic Glossary

Blow Gun

A handheld pneumatic trigger nozzle connected to an air hose used to direct a high-pressure stream of compressed air to clean parts.

After cleaning a part in solvent or washing it with water, you need to dry it completely to prevent rust. A blow gun attaches to your air line and uses a simple trigger valve to blast compressed air. It is ideal for clearing dust, dirt, and water out of blind bolt holes, cleaning brake assemblies, and drying off machined parts before reassembly.

Never point an air blow gun at your skin or eyes. The high-pressure stream can force dirt particles under your skin or push air directly into your bloodstream, which is a lethal medical emergency. OSHA regulations require safety blow guns to have small vent holes on the side of the nozzle tip. This drops the tip pressure below 30 PSI if the nozzle gets blocked, preventing injury.

Frequently Asked Questions

They are safety relief vents. If you press the nozzle tip against your skin or block it, the air escapes through the vents, keeping the pressure below the OSHA limit of 30 PSI to prevent air embolism.
It is not recommended. Blasting dry brake dust with compressed air sends hazardous asbestos or metallic fibers into the air where you can inhale them. Use wet brake cleaner spray instead.
The rubber tip creates a tight seal against fluid ports. This allows you to blow low-pressure air through oil passages or cooling jackets to clear out old fluid and debris.
Most blow guns feature a variable-flow trigger. Squeezing the lever gently releases a light puff of air, while pressing it down fully delivers a high-velocity blast.

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