Sized to prevent flashing (bubbling) of the liquid refrigerant before it reaches the expansion valve. 3. Two-Phase Flow and Vapor/Liquid Separation
First, it is crucial to clarify terminology. There is no single document officially titled “The IIAR Ammonia Refrigeration Piping Handbook.” Instead, the industry references
Proper line sizing balances installation costs against operational efficiency. Piping that is too small causes excessive pressure drops, which forces compressors to work harder and increases energy consumption. Conversely, oversized piping reduces vapor velocity, preventing refrigeration oil from returning to the compressor. Iiar Ammonia Refrigeration Piping Handbook Pdf
As of 2025, IIAR continues to align with global standards. Future revisions of the piping handbook are expected to include:
| | Critical Requirements | |-----------|----------------------------| | Material | Seamless carbon steel (ASTM A106 Gr B or A333 Gr 6 for low temp). No copper or galvanized (ammonia attacks them). | | Pressure Rating | Minimum Class 300 fittings and flanges (even for low-pressure systems). | | Valves | Steel, back-seating, with bonnet wrenches. No brass or aluminum. | | Supports | Max spacing per pipe size (e.g., 1" = 8 ft; 6" = 17 ft). Allow sliding at low temp to avoid stress. | | Flexibility | Must calculate thermal expansion (ammonia systems often cycle from -40°F to +100°F). Use loops or expansion joints. | | Hydrostatic Test | 1.5x design pressure, but never less than 300 psig for high-side. | | Leak Test | Dry nitrogen with soap bubbles or electronic detector (halide torch is obsolete for ammonia). | Sized to prevent flashing (bubbling) of the liquid
Compiled by contractor experts M. Kent Anderson and Lane Bonebrake, this handbook combines the collective expertise of refrigeration contractors, ASHRAE Handbook sources, and decades of field knowledge, representing a lifetime of refrigeration experience.
The IIAR Ammonia Refrigeration Piping Handbook serves as the industry standard, bridging theoretical design with practical, field-proven applications for anhydrous ammonia systems. It provides comprehensive data on pipe sizing, safety guidelines regarding prohibited materials, and updated insulation standards for engineers and contractors. For more details, visit OSHA . The Ammonia Refrigeration Piping Handbook - Google Books There is no single document officially titled “The
Every joint, valve body, and hanger support must be perfectly sealed. A single pinhole can cause localized icing, which splits the insulation and rusts the carbon steel pipe underneath. 5. Code Compliance and Documentation