N.Y.C. Admin. Code § MC 1104: Section MC 1104: System Application Requirements

1104.1 General.

The refrigerant, occupancy and system classification cited in this section shall be determined in accordance with Sections 1103.1, 1103.2 and 1103.3, respectively. For refrigerant blends assigned dual classifications, as formulated and for the worst case of fractionation, the classifications for the worst case of fractionation shall be used. For blends assigned only a single safety group classification in Table 1103.1 or ASHRAE 34, that classification shall be used. Use of a Group A3 or Group B3 refrigerant is prohibited. In an industrial occupancy, a Group A3 or Group B3 refrigerant may be used in high- or low-probability systems only when approved by the commissioner and the Commissioner of the Fire Department. Such use will be approved only if the applicant can demonstrate to the satisfaction of the commissioner and the Commissioner of the Fire Department that the use of the refrigerant is a necessity and does not represent a substantial risk to life, limb, health or property.

1104.2 Machinery room.

Except as provided in Sections 1104.2.1 and 1104.2.2, all components containing the refrigerant shall be located either outdoors or in a machinery room where the quantity of refrigerant in an independent circuit of a system exceeds the amounts shown in Table 1103.1. For refrigerant names not listed in Table 1103.1, the same requirement shall apply when the amount for any named component exceeds that indicated in Table 1103.1 for that component. This requirement shall also apply when the combined amount of the named components exceeds a limit of 69,100 parts per million (ppm) by volume. Machinery rooms required by this section shall be constructed and maintained in accordance with Section 1105 for Group A1 and B1 refrigerants and in accordance with Sections 1105 and 1106 for Group A2, B2, A3 and B3 refrigerants. Nothing in this section shall be construed to allow the use of Group A3 and B3 refrigerants if otherwise prohibited.

Exceptions:

1. Machinery rooms are not required for listed equipment and appliances containing not more than 6.6 pounds (3 kg) of refrigerant, regardless of the refrigerant's safety classification, where installed in accordance with the equipment's or appliance's listing and the equipment or appliance manufacturer's installation instructions.

2. Piping in conformance with Section 1107 of this chapter and Section 8.10 of ASHRAE 15 is allowed in other locations to connect components installed in a machinery room with those installed outdoors.

1104.2.1 Institutional occupancies.

The amounts shown in Table 1103.1 shall be reduced by 50 percent for all areas of institutional occupancies except kitchens, laboratories and mortuaries. The total of all Group A2, B2, A3 and B3 refrigerants shall not exceed 550 pounds (249.4 kg) in occupied areas or machinery rooms. Nothing in this section shall be construed to allow the use of Group A3 and B3 refrigerants if otherwise prohibited.

1104.2.2 Industrial occupancies and refrigerated rooms.

This section applies only to industrial occupancies and refrigerated rooms for manufacturing, food and beverage preparation, meat cutting, other processes and storage. Machinery rooms are not required where all of the following conditions are met:

1. The space containing the machinery is separated from other occupancies by tight construction with tight-fitting doors.

2. Access is restricted to authorized personnel.

3. The floor area per occupant is not less than 100 square feet (9.3 m

2

). Where provided with egress directly to the outdoors or into building exits meeting the requirements of the New York City Building Code, the minimum floor area shall not apply.

4. Refrigerant detectors are installed as required for machinery rooms in accordance with Section 1105.3.

5. Surfaces having temperatures exceeding 800°F (426.7°C) and open flames are not present where any Group A2, B2, A3 or B3 refrigerant is used (see Section 1104.3.3). Nothing in this section shall be construed to allow the use of Group A3 and B3 refrigerants if otherwise prohibited.

6. All electrical equipment and appliances conform to Class 1, Division 2, hazardous location classification requirements of the New York City Electrical Code where the quantity of any Group A2, B2, A3 or B3 refrigerant, other than ammonia, in a single independent circuit would exceed 25 percent of the lower flammability limit (LFL) upon release to the space based on the volume determined by Section 1104.4. Nothing in this section shall be construed to allow the use of Group A3 and B3 refrigerants if otherwise prohibited.

7. All refrigerant-containing parts in systems exceeding 100 hp (74.6 kW) drive power, except evaporators used for refrigeration or dehumidification; condensers used for heating; control and pressure relief valves for either; and connecting piping, shall be located either outdoors or in a machinery room.

1104.3 Refrigerant restrictions.

Refrigerant applications, maximum quantities and use shall be restricted in accordance with Sections 1104.3.1 through 1104.3.3.

1104.3.1 Air-conditioning for human comfort.

Group A3, B1, B2 and B3 refrigerants shall not be used in high-probability air conditioning systems for human comfort.

Exceptions:

1. Sealed absorption and unit air-conditioning systems having refrigerant quantities not exceeding those set forth in Table 1103.1.

2. Industrial occupancies.

Nothing in this section shall be construed to allow the use of Group A3 and B3 refrigerants if otherwise prohibited.

Table 1104.3.1 Special Quantity Limits for Sealed Ammonia/Water Absorption and Self-Contained Systems

Type of Refrigeration System

Maximum Pounds for Various Occupancies

Institutional

Public Assembly / Large Mercantile

Residential

Commercial

Sealed Ammonia / Water Absorption System

In exit access or lobbies

0

0

3.3

3.3

In adjacent outdoor locations

0

0

22

22

In other than exit access lobbies

0

6.6

6.6

22

Unit Systems

In other than exit access or lobbies

0

0

6.6

22

For SI: 1 pound = 0.454 kg.

1104.3.2 All occupancies.

The total of all Group A2, B2, A3 and B3 refrigerants other than R-717, ammonia, shall not exceed 1,100 pounds (499 kg) except where approved. Nothing in this section shall be construed to allow the use of Group A3 and B3 refrigerants if otherwise prohibited.

1104.3.3 Protection from refrigerant decomposition.

Where any device having an open flame or surface temperature greater than 800°F (426.7°C) is used in a room containing more than 6.6 pounds (3 kg) of refrigerant in a single independent circuit, a hood and exhaust system shall be provided in accordance with Section 510. Such exhaust system shall exhaust combustion products to the outdoors.

Exception: A hood and exhaust system shall not be required where any of the following apply:

1. The refrigerant is R-717, R-718 or R-744.

2. The combustion air is ducted from the outdoors in a manner that prevents leaked refrigerant from being combusted.

3. A refrigerant detector is used to stop the combustion in the event of a refrigerant leak (see Sections 1105.3 and 1105.5).

1104.4 Volume calculations.

Volume calculations shall be in accordance with Sections 1104.4.1 through 1104.4.3.

1104.4.1 Noncommunicating spaces.

Where the refrigerant-containing parts of a system are located in one or more spaces that do not communicate through permanent openings or HVAC ducts, the volume of the smallest, enclosed occupied space shall be used to determine the permissible quantity of refrigerant in the system.

1104.4.2 Communicating spaces.

Where an evaporator or condenser is located in an air duct system, the volume of the smallest, enclosed occupied space served by the duct system shall be used to determine the maximum allowable quantity of refrigerant in the system.

Exception: If airflow to any enclosed space cannot be reduced below one-quarter of its maximum, the entire space served by the air duct system shall be used to determine the maximum allowable quantity of refrigerant in the system.

1104.4.3 Plenums.

Where the space above a suspended ceiling is continuous and part of the supply or return air plenum system, this space shall be included in calculating the volume of the enclosed space.