OSHA Instruction STD 01-13-001

Reduction of Air Pressure below 30 PSI for Cleaning Purposes

(Old directive number: STD 1-13.1)
Released by: U.S. Department of Labor Occupational Safety & Health Administration (OSHA)

3. Interpretation
The phrase "reduce to less than 30 PSI (2 bar)" means that the downstream pressure of the air at the nozzle (nozzle pressure) or opening of a gun, pipe, cleaning lance, etc., used for cleaning purposes will remain at a pressure level below 30 PSI for all static conditions. The requirements for dynamic flow are such that in the case when dead ending occurs, a static pressure at the main orifice shall not exceed 30 PSI. This require-
ment is necessary in order to prevent a back pressure buildup in case the nozzle is obstructed or dead ended. There is no intent to restrict the diameter of the nozzle orifice or the volume (CFM) flowing from it. 

"Effective chip guarding" means any method or equipment, which will prevent a chip or particle (of whatever size) from being blown into the eyes or unbroken skin of the operator or other workers. Effective chip guarding may be separate from the air nozzle, as in the case where screens or barriers are used. The use of protective cone air nozzles are acceptable in general for protection of the operator; but barriers, baffles or screens may be required to protect other workers if they are exposed to flying chips or particles. 

In Other Words
When dead-ending occurs, static pressure at the main orifice should not exceed 30 PSI.

Compliance of CEJN Pneumatic Safety Products   
With less than 30 PSI maximum outlet pressure when dead-ended, the following
CEJN Series 208 blowgun accessories comply:
• Venturi nozzle 
• Bypass nozzle 
• Air curtain nozzle 
• Silencer
• Silencer nozzle
• Tube regulator: 4" (90 mm)
• Star-Tip extension tubes

CEJN Series 210 MultiFLOW blowgun accessories comply:
• Orginal, adjustable jet nozzle
• Star-tip nozzle