Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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

September 11, 1995

Mr. Jeffrey O. Brown
Howard Hall Division R.W.
Greeff & Co., Inc.
777 West Putnam Avenue
Greenwich, Connecticut 06830

Dear Mr. Brown:

This is in response to your March 20, 1995 letter requesting an interpretation regarding the applicability of Process Safety Management standard, 29 CFR 1910.119, to a 50% solution of Hydroxylamine (CAS #7803-49-8).

The substances listed in Appendix A of the standard without specified concentration limits, such as Hydroxylamine, are intended to be covered by the PSM standard at commercial grade percentages. OSHA defines "commercial grade" as a typical maximum concentration of the chemical that is commercially available and shipped. Hydroxylamine comes as both a liquid and a solid. Assuming the commercial grade of the liquid form is near a 99% concentration, a 50% solution would not be covered by the standard. However, if your company receives a commercial grade concentration, either liquid or solid, and dilutes the chemical on-site, the undiluted quantity would be subject to the PSM standard should the 2,500 pound threshold quantity be available.

We appreciate your interest in occupational safety and health. If we can be of further assistance, please contact Ron Davies at (202)219-8041.


John B. Miles, Jr., Director
Directorate of Compliance Programs