When using compressed air for cleaning OSHA has issued a directive STD 01-13-001 – STD 1-13.1 that states ”
“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 requirement is necessary in order to prevent a back pressure buildup in case the nozzle is obstructed or dead ended.”
The reason for concern is should the nozzle come into contact with the skin, the pressure is not sufficient enough to pierce the skin and cause a blood embolism. There a couple of methods to achieve this. One is using a pressure regulator and reduce the pressure to 30 psi. At this low of pressure the nozzle becomes less than effective for most cleaning purposes. Another Commercial design is side drilled holes into the nozzle. While this provides a degree of safety, it does nothing for noise abatement or efficiency.
A more superior method is having the safety feature permanently designed in like the EXAIR Super air nozzles. In this diagram you see that the orifices are embedded down in between the fins thus preventing blockage. Another feature of this design is as the air exits the orifices, a vacuum is created between the fins drawing in ambient air and adding it to the blow off stream of air. This slower moving outer entrained air stream reduces the sound levels, thus this design provides both safety and efficiency.
To further improve on safety a protective chip shield can be added to protect workers from flying debris and prevent splash back. Between the highly efficient, safe nozzle and the protective chip shield you can provide your workers with the tool they need for effective safe blow off.
Feel welcomed to call us here at the factory and ask to speak with one of our application engineers and they will fill you in on all the details.