In the 2021 International Mechanical Code (IMC), the International Association of Ammonia Refrigeration (IIAR) was successful in simplifying the code requirements for refrigeration systems using Anhydrous Ammonia (NH3). The code now reads:
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1101.1.2 Ammonia refrigerant Refrigeration systems using ammonia as the refrigerant shall comply with IIAR 2, IIAR 3, IIAR 4, and IIAR 5 and shall not be required to comply with this chapter. |
Here is a look at the REVISED code requirements for refrigeration systems using refrigerants OTHER than NH3:
1101.1.1 Refrigerants other than ammonia. Refrigerant piping design and installation for systems containing a refrigerant other than ammonia, including pressure vessels and pressure relief devices, shall comply with this chapter and ASHRAE 15.
TABLE 1101.2 FACTORY-BUILT EQUIPMENT AND APPLIANCES
| EQUIPMENT | STANDARDS |
| Refrigeration fittings, including press-connect, flared and threaded | UL 109 and UL 207 |
| Air-conditioning equipment | UL 1995 or UL/CSA 60335-2-40 |
| Packaged terminal air conditioners and heat pumps | UL 484 or UL/CSA 60335-2-40 |
| Split-system air conditioners and heat pumps | UL 1995 or UL/CSA 60335-2-40 |
| Dehumidifiers | UL 474 or UL/CSA 60335-2-40 |
| Unit coolers | UL 412 or UL/CSA 60335-2-89 |
| Commercial refrigerators, freezers, beverage coolers and walk-in coolers | UL 471 or UL/CSA 60335-2-89 |
| Refrigerating units and walk-in coolers | UL 427 or UL 60335-2-89 |
| Refrigerant-containing components and accessories | UL 207 |
1105.8 Emergency pressure control system
Emergency pressure control systems shall be provided with an emergency pressure control system in accordance with Section 605.10 of the International Fire Code.
1105.9 Means of egress
Machinery rooms larger than 1,000 square feet (93 m2) shall have not less than two exits or exit access doorways. Where two exit access doorways are required, one such doorway is permitted to be served by a fixed ladder or an alternating tread device. Exit access doorways shall be separated by a horizontal distance equal to one-half the maximum horizontal dimension of the room. All portions of machinery rooms shall be within 150 feet (45 720 mm) of an exit or exit access doorway. An increase in exit access travel distance is permitted in accordance with Section 1017.1 of the International Building Code. Exit and exit access doorways shall swing in the direction of egress travel and shall be equipped with panic hardware, regardless of the occupant load served. Exit and exit access doorways shall be tight fitting and self-closing.
1106.4.1 Ventilation system activation
Ventilation shall be activated by the refrigerant detection system in the machinery room. Refrigerant detection systems shall be in accordance with Section 605.8 of the International Fire Code and all of the following:
1. The detectors shall activate at or below a refrigerant concentration of 25 percent of the LFL.
2. Upon activation, the detection system shall activate the emergency ventilation system required by Section 1106.4.2.
3. The detection, signaling and control circuits shall be supervised.
1107.2 Used materials
Used pipe, fittings, valves, and other materials that are to be reused shall be clean and free from foreign materials and shall be approved for reuse.
1107.3 Materials rating
Materials, joints and connections shall be rated for the operating temperature and pressure of the refrigerant system. Materials shall be suitable for the type of refrigerant and type of lubricant in the refrigerant system. Magnesium alloys shall not be used in contact with any halogenated refrigerants. Aluminum, zinc, magnesium and their alloys shall not be used in contact with R-40 (methyl chloride).
1107.6 Valves
Valves shall be of materials that are compatible with the type of piping material, refrigerants and oils in the system. Valves shall be listed and labeled and rated for the temperatures and pressures of the refrigerant systems in which the valves are installed.
1107.7 Flexible connectors, expansion and vibration compensators
Flexible connectors and expansion and vibration control devices shall be listed and labeled for use in refrigerant systems.
SECTION 1108 is no longer called FIELD TEST but was changed to cover JOINTS AND CONNECTIONS
SECTION 1109 REFRIGERANT PIPE INSTALLATION is a new section
1109.1 General. Refrigerant piping installations, other than R-717 (ammonia) refrigeration systems, shall comply with the requirements of this section. The design of refrigerant piping shall be in accordance with ASME B31.5.
SECTION 1110 REFRIGERATION PIPING SYSTEM TEST is new section
1110.1 General. Refrigerant piping systems, other than R-717 (ammonia) refrigeration systems, that are erected in the field shall be pressure tested for strength and leak tested for tightness, in accordance with the requirements of this section, after installation and before being placed in operation. Tests shall include both the high- and low-pressure sides of each system.
Exception: Listed and labeled equipment, including compressors, condensers, vessels, evaporators, gas bulk storage tanks, safety devices, pressure gauges and control mechanisms, shall not be required to be tested.
1110.2 Exposure of refrigerant piping system. Refrigerant pipe and joints installed in the field shall be exposed for visual inspection and testing prior to being covered or enclosed.
1110.3 Test gases
The medium used for pressure testing the refrigerant system shall be one of the following inert gases: oxygen-free nitrogen, helium or argon.
For R-744 refrigerant systems, carbon dioxide shall be allowed as the test medium.
For R-718 refrigerant systems, water shall be allowed as the test medium.
Oxygen, air, combustible gases, and mixtures containing such gases shall not be used as a test medium.
Systems erected on the premises with tubing not exceeding 5/8 inch (15.9 mm) outside diameter shall be allowed to use the refrigerant identified on the nameplate label or marking as the test medium.
1110.4 Test apparatus
The means used to pressurize the refrigerant piping system shall have on its outlet side a test pressure measuring device and either a pressure-limiting device or a pressure-reducing device.
The test pressure measuring device shall have an accuracy of ±3 percent or less of the test pressure and shall have a resolution of 5 percent or less of the test pressure.
1110.5 Piping system pressure test and leak test
The refrigerant piping system shall be tested as a whole or separate tests shall be conducted for the low-pressure side and high-pressure side of the piping system. The refrigerant piping system shall be tested in accordance with both of the following methods:
1. The system shall be pressurized for a period of not less than 60 minutes to not less than the lower of the design pressures or the setting of the pressure relief device(s). The design pressures for testing shall be the pressure listed on the label nameplate of the condensing unit, compressor, compressor unit, pressure vessel or other system component with a nameplate. Additional test gas shall not be added to the system after the start of the pressure test. The system shall not show loss of pressure on the test pressure measuring device during the pressure test. Where using refrigerant as a test medium in accordance with Section 1110.3, the test pressure shall be not less than the saturation dew point pressure at 77°F (25°C).
2. A vacuum of 500 microns shall be achieved. After achieving a vacuum, the system shall be isolated from the vacuum pump. The system pressure shall not rise above 1,500 microns for a period of not less than 10 minutes. 1110.5.1 Joints and refrigerant-containing parts in air ducts. Joints and all refrigerant-containing parts of a refrigerating system located in an air duct of an air-conditioning system that conveys conditioned air to and from human-occupied spaces shall be tested at a pressure of 150 percent of the higher of the design pressure or pressure relief device setting.
1110.5.2 Limited charge systems
Limited charge systems with a pressure relief device, erected on the premises, shall be tested at a pressure not less than one and one-half times the pressure setting of the relief device. Listed and labeled limited charge systems shall be tested at the equipment or appliance design pressure.
1110.6 Booster compressor
Where a compressor protected by a pressure relief device is used as a booster to obtain an intermediate pressure, and such compressor discharges into the suction side of another compressor, the booster compressor shall be considered to be a part of the low-pressure side of the system.
1110.7 Centrifugal/nonpositive displacement compressors
Where testing systems using centrifugal or other nonpositive displacement compressors, the entire system shall be considered to be the low-pressure side for test purposes.
1110.8 Contractor or engineer declaration
The installing contractor or registered design professional of record shall issue a certificate of test to the code official for all systems containing 55 pounds (25 kg) or more of refrigerant.
The certificate shall give the test date, name of the refrigerant, test medium and the field test pressure applied to the high-pressure side and the low-pressure side of the system.
The certification of test shall be signed by the installing contractor or registered design professional and shall be made part of the public record.