Purging, Piping, and Safety

Table of Contents

Chapter 1: Purging Air and Noncondensables

Topics: Materials to be purged; Effects of noncondensables; Power penalty; Purge point locations; Automatic purging; Economics of purging

Learning Objectives:

• List common noncondensable vapors and discuss their effects in a refrigeration system.
• Discuss the power penalty resulting from noncondensable gases in terms of compression and loss of refrigeration capacity.
• Explain how to determine the presence of noncondensables.
• Explain how to minimize the entrance of noncondensables and describe common entry points.
• Compare the features and operation of manual and automatic purging equipment and name the best connection points for the purge unit.
• Discuss the economic benefits of the purge unit in terms of typical payback times.

Chapter 2: Ammonia System Piping

Topics: Pressure drop in pipes; Laminar and turbulent flow; Line sizing, flow rate, suction line pressure drop, discharge line pressure charts; Special piping situations

Learning Objectives:

• Discuss the relationship between pressure drop requirements and pipe sizing.
• Discuss the factors that affect the pressure drop in a pipe.
• Explain the significance of the Reynolds number and the distinction between laminar and turbulent flow.
• Discuss the use of various kinds of line sizing charts including flow rate tables, equivalence tables for fittings and valves, and pressure drop charts.
• Explain how to select the proper suction line, discharge line, and liquid line sizing for an ammonia system.
• Discuss special piping situations that require alternative sizing or installation.

Chapter 3: Ammonia System Safety Codes and Guidelines

Topics: Codes for ammonia refrigeration systems; ANSI/ASHRAE 15-1994; ASMEB 31.5; IIAR2; IIAR bulletin 111; IIAR bulletin 112

Learning Objectives:

• Describe the basic differences between ASHRAE and ASME codes and IIAR standards and guidelines.
• Discuss several main points in the ASHRAE 15-1994 safety code for mechanical refrigeration.
• Describe code requirements based on the occupancy classifications, leak probability classifications, and refrigerant characteristic classifications.
• Describe several requirements in the ASME B 31.5 refrigeration piping code concerning the materials and fabrication of refrigeration piping systems.
• Name several safety requirements specified by IIAR 2 for ammonia refrigeration equipment.
• Describe the kinds of information provided by IIAR bulletins.

Chapter 4: OSHA Process Safety Management

Topics: OSHA regulations; PSM requirements; Estimation of ammonia inventory; PSM plan development; Process safety information, hazard analysis; Standard operating procedures; Contractor procedures

Learning Objectives:

• Discuss the purposes of Process Safety Management and describe the thirteen elements that make up PSM.
• Describe the process for estimating a plant's ammonia inventory and establishing a plant ammonia library and explain why each is needed.
• Discuss the personnel and steps involved in developing a PSM plan for a specific refrigeration plant.
• Describe the process hazard analysis (PHA) and explain how it can reduce the likelihood of ammonia accidents and spills.
• Describe the requirements for preparing standard operating procedures (SOPs) for all normal plant service, repair, and maintenance.
• Discuss contractor responsibilities for PSM.
• Discuss the importance of management-of-change procedures in keeping paperwork up to date.

Chapter 5: EPA Regulations and Ammonia Safety

Topics: 40 CFR 68; Worst case/alternate ammonia release scenario; Elements in common with OSHA PSM; Penalties for nonconformance

Learning Objectives:

• Describe the purposes of the EPA Risk Management Plan and compare it to the OSHA Process Safety Management program.
• Explain the reasoning behind the dual hazard assessment requirements of a worst-case ammonia release and the more practical alternative ammonia release.
• Discuss the toxic end point criteria for an ammonia release and distinguish between rural and urban end points and differences in requirements.
• Discuss the importance and difficulties of presenting the required release data and plan to the community.
• Discuss the hazards of working with ammonia and the importance of using personal protective equipment to avoid or minimize the effects of an ammonia release.
• Describe correct first aid procedures pertaining to contact with ammonia vapor and liquid.

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