OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

April 3, 2000

Mr. Andrew Logan, Jr.
The ArmaKleen Co.
469 N. Harrison St.
Princeton, NJ 08543

Dear Mr. Logan:

Thank you for your February 25, 2000 letter to the Occupational Safety and Health Administration's (OSHA's) [Office of General Industry Enforcement (GIE)]. You have requested an interpretation of 29 CFR 1910.244(b), Abrasive Blast Cleaning Nozzles, because you have, "...observed that the lower end model abrasive equipment did not appear to utilize dead-man switches as their control devices. Simple ball valves appeared in use."

Question: Is there an operational parameter in abrasive blasting under which a dead-man switch is not required?

Reply: The operational parameter about which you are inquiring is found in 29 CFR 1910.244(b), Abrasive Blast Cleaning Nozzles. The standard reads, "The blast cleaning nozzles shall be equipped with an operating valve which must be held open manually. A support shall be provided on which the nozzle may be mounted when it is not in use."

Abrasive blasting is the high velocity bombardment of a surface by an abrasive agent propelled, in most operations, by pneumatic pressure. Under such pressure, and in the event the nozzle is accidentally released from the operator's hand, the nozzle and hose assembly could become very dangerous. The unsecured flexible assembly could begin whipping about, striking anyone or anything in its path.

Although the referenced standard does not differentiate between a "dead-man switch" and a "simple ball valve," it requires that the blast cleaning nozzle(s) have an operating valve, that must be held open manually. Therefore, in fact, the nozzle(s) must be equipped with a "dead-man" control, such as a spring-actuated switch or valve, so that the media will automatically cease to blast or will "shut off" when the lever is released by the operator. The "simple ball valve" that you refer to in your letter when used as the blast cleaning nozzle's operating valve, does not meet the requirement of the standard because the lever can remain in the "on" position without being "manually held open." Thus, if the operator loses control of the equipment, the nozzle will continue to blast and could cause severe injury to the operator and other employees in the area.

However, we realize that "simple ball valves" may be used to regulate the airflow upstream in the hose assembly. In this case, if a dead-man control is integrated into the apparatus where an operator must manually hold open the valve in order to operate the equipment, then the equipment would comply with the above standard.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. Please be aware that OSHA's enforcement guidance is subject to periodic review and clarification, amplification, and correction. Such guidance could also be affected by subsequent rulemaking. In the future, should you wish to verify that the guidance herein remains current, you may consult OSHA's website at
http://www.osha.gov. If you have any further questions, please feel free to contact the [Office of General Industry Enforcement] at 202-693-1850.


Richard E. Fairfax, Director
[Directorate of Enforcement Programs]

[Corrected 6/2/2005]