What is this information? Department of Transportation hazard labels, and a general description of the chemical. Flammability 1 Must be preheated before ignition can occur. Instability 0 Normally stable, even under fire conditions.
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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. In support of your belief you stated in your letter that a threshold quantity TQ of 10, pounds Also, you stated your opinion that the nature of ammonia used in a refrigeration system does not meet the criteria for a Process Hazard Analysis PHA when all that occurs is a simple change of state from liquid to gas and back to liquid in a closed system.
The purpose of the PSM standard is to prevent or minimize the consequences of an uncontrolled release from a workplace process containing a threshold quantity or greater amount of highly hazardous chemicals such as 10, pounds or more of NH 3.
As discussed in the background section on page of the preamble to the PSM Final Rule, there exists a potential for an accidental release if a HHC is not properly controlled, regardless of the industry.
Thus, the PSM standard is aimed not only at the petrochemical industry as stated in your letter but also at other industries, irrespective of size, at which there are processes containing HHC's such as NH 3. A copy of the Final Rule is enclosed for your use. Please note on page that the TQ for anhydrous ammonia was increased from pounds The National Fire Protection Association NFPA rates anhydrous ammonia as a 3 on a scale of 4 - a most severe toxic health hazard and as a 1 on a scale of 4 - a flammable gas.
There is an extensive history of catastrophic releases of NH 3 in the nations workplaces resulting in severe injuries and death. Although NH 3 would not be flammable as defined in As such, NH 3 is flammable or explosive when subjected to a flame or in a fire. In consideration of the hazards noted above, OSHA believes that the release of anhydrous ammonia from a workplace process containing a TQ or greater amount presents a potential catastrophic situation including potential exposure of employees and therefore is covered by the PSM standard.
Thank you for your interest in occupational safety and health. If we may be of further assistance, please contact us. Sincerely, H. Standard Number:. June 2, Mr.
Tanner Industries, Inc. Corporate emergency telephone number: Chemtrec: Please click here for a printable anhydrous ammonia MSDS sheet. Hazard Description Ammonia is an irritant and corrosive to the skin, eyes, respiratory tract and mucous membranes. Exposure to liquid or rapidly expanding gases may cause severe chemical burns and frostbite to the eyes, lungs and skin. Skin and respiratory related diseases could be aggravated by exposure.