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Evaluation and Control

An effective process safety management program requires a systematic approach to evaluating the whole chemical process. The following references aid in evaluating process hazards in the workplace.

  • Ammonia Refrigeration. OSHA eTool.
  • Risk Management Program Guidance. Environmental Protection Agency (EPA).
    • General Risk Management Program Guidance. Contains an updated risk management program, which includes an appendix specifically addressing ammonia refrigeration facilities. While this guidance is primarily designed to assist with the development and implementation of a risk management plan as required by the EPA, much of the information can also be used by those who are required to comply with the OSHA Process Safety Management Standard (29 CFR 1910.119).
      • Appendix E: Supplemental Risk Management Program Guidance for Ammonia Refrigeration Facilities (PDF).

        NOTE: This appendix replaces the former stand-alone document "Risk Management Program Guidance for Ammonia Refrigeration." This appendix is intended for facilities with ammonia refrigeration systems (e.g., food processors and distributors, refrigerated warehouses). It covers only anhydrous ammonia and provides offsite consequence analyses that are specific to the ways in which ammonia is handled in an ammonia refrigeration system.

  • Model Risk Management Program and Plan for Ammonia Refrigeration (PDF). Environmental Protection Agency (EPA), (May 1996). Helps owners and operators of ammonia refrigeration facilities comply with the OSHA Process Safety Management Standard (29 CFR 1910.119) and EPA's General Risk Management Program Guidance (40 CFR Part 68). Specific guidance is given on how to perform the Hazard Assessment, and the requirement for a Management System, Prevention Program, and Emergency Response Plan. Also included is a brief report of past accidental releases of ammonia and their root causes from EPA's Accidental Release Information Program (ARIP) database.
  • Shock to the System. U.S. Chemical Safety Board (CSB) Safety Video. Details key lessons for preventing hydraulic shock in ammonia refrigeration systems based on the CSB's investigation into the accident at Millard Refrigerated Services Inc. on August 23, 2010.
Worker Protection

Accidental releases of ammonia from refrigeration facilities have resulted in both injuries and deaths to employees of these facilities. These injuries and deaths are caused from contact with both liquid and vapor forms of ammonia. Because refrigeration systems operate at elevated pressures, additional care must be taken to maintain and operate these systems so as to prevent releases with potentially catastrophic consequences. OSHA has developed this page to assist employers in identifying and controlling the hazards associated with the operation and maintenance of ammonia refrigeration systems.

IIAR Bulletins
  • Bulletin 108 - Guidelines for Water Contamination in Ammonia Refrigeration Systems. (1986). Addresses the water contamination in ammonia refrigeration systems that has always been a problem, as owners typically know they have water in a system, but may not be familiar with how it got there; measures to quantify the amounts, analyzing the specific penalties it causes on the system performance; and removing the water in a safe manner. Offers insights on where the water can come from and how to minimize continued infiltration. Provides an analytical approach to quantifying water concentrations, and recommends apparatus to remove the water.
  • Bulletin 109 - Guidelines for: IIAR Minimum Safety Criteria for a Safe Ammonia Refrigeration System. (1997). Embraces an IIAR goal of ensuring that ammonia refrigeration systems are engineered, constructed and operated in a safe manner. Provides detailed lists of items to consider when designing, inspecting, or operating a system. Addresses such issues as housekeeping, record keeping, code considerations and personnel safety equipment. Provides inspection checklist forms for compressors, condensers, evaporators, vessels and heat exchangers to check system installation against recognized industry safety requirements.
  • Bulletin 110 - Guidelines for: Start-Up, Inspection and Maintenance of Ammonia Mechanical Refrigerating Systems. (March 2002). Covers ammonia characteristics and hazards, inspection and maintenance of equipment, start-up issues, reference standards, safety equipment, and log book record keeping. Provides definitions of system components and terms to help in understanding ammonia systems.
  • Bulletin 114 - Identification of Ammonia Refrigeration Piping and System Components. (2014). Provides a comprehensive ammonia labeling scheme for companies in need of an identification system that "covers it all." Offers recommendations on label sizes, colors, installation locations, and label material requirements.
  • bulletin 116 - Guidelines for: Avoiding Component Failure in Industrial Refrigeration Systems Caused by Abnormal Pressure or Shock. (1992). Identifies three significant factors that can lead to ammonia refrigeration system damage and personnel injury: trapped liquid, sudden liquid deceleration, and vapor propelled liquid. Explains the most likely causes for each of these problems and provides design, operation and servicing tips that can minimize the chances of them occurring. Offers numerous suggestions on making hot gas defrost operations safer and more effective.
  • Process Safety Management & Risk Management Program Guidelines, Vol. 1 & Vol. 2. Provides guidance on the interpretation and implementation of both OSHA's Process Safety Management Standard (PSM) and EPA's Risk Management Program (RMP). Guidelines. Provides a template for end users to update or create PSM/RMP programs that will aid in practically applying management procedures in direct response to PSM/RMP rules and regulations and in establishing and maintaining a safe ammonia refrigeration facility

*Accessibility Assistance: Contact OSHA's Directorate of Technical Support and Emergency Management at (202) 693-2300 for assistance accessing PDF materials.

All other documents, that are not PDF materials or formatted for the web, are available as Microsoft Office® formats and videos and are noted accordingly. If additional assistance is needed with reading, reviewing or accessing these documents or any figures and illustrations, please also contact OSHA's Directorate of Technical Support and Emergency Management at (202) 693-2300.

**eBooks - EPUB is the most common format for e-Books. If you use a Sony Reader, a Nook, or an iPad you can download the EPUB file format. If you use a Kindle, you can download the MOBI file format.

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