1106.2 Refrigeration Machinery Room, General Requirements
Exception: Refrigerant detectors are not required where only systems using R-718 (water) are located in the refrigeration machinery room.
- The refrigerant detector shall perform automatic self-testing of sensors. Where a failure is detected, a trouble signal shall be activated.
- The refrigerant detector shall have one or more set points to activate responses in accordance with Section 122.214.171.124 or Section 1107.1.7.
- The refrigerant detector as installed, including any sampling tubes, shall activate responses within a time not to exceed 30 seconds after exposure to refrigerant concentration exceeding the set point value specified in Section 1126.96.36.199 or Section 1107.1.7.
To obtain a reduced airflow for normal ventilation, multiple fans or multispeed fans shall be used. Provision shall be made to supply make-up air to replace that being exhausted. Ducts for supply and exhaust to the machinery room shall serve no other area. The makeup air supply locations shall be positioned relative to the exhaust air locations to avoid short-circuiting. Inlets to the exhaust ducts shall be located in an area where refrigerant from a leak will concentrate, in consideration of the location of the replacement supply air paths, refrigerating machines, and the density of the refrigerant relative to air.
Inlets to exhaust ducts shall be within 1 foot (305 mm) of the lowest point of the machinery room for refrigerants that are heavier than air, and shall be within 1 foot (305 mm) of the highest point for refrigerants that are lighter than air. The discharge of the exhaust air shall be to the outdoors in such a manner as not to cause a nuisance or danger.
Q = 100√G
Q = Air flow rate, cubic feet per minute.
G = Refrigerant mass in largest system, pounds.
For SI units: 1 cubic foot per minute = 0.00047 m3/s, 1 pound = 0.453 kg
TABLE 1188.8.131.52 REQUIRED AIRFLOW FOR GROUP A2L REFRIGERANTS
|REFRIGERANT||MINIMUM AIR FLOW*|
For SI units: 1 cubic foot per minute = 0.00047 m3/s
* The values were tabulated from the following equation:
QA2L ≥ [(ρ.v.A)/(LFL.0.50)] (Equation 1184.108.40.206)
|ρ||=||Refrigerant density, pounds per cubic feet (kg/m3).|
|v||=||Refrigerant velocity equal to the refrigerant acoustic velocity (speed of sound), feet per second (m/s).|
|A||=||Cross-section flow area of refrigerant leak, square feet (m2), A = 0.00136 ft2 (0.000126 m2).|
|LFL||=||Lower Flammability Limit, or ETFL60 where no LFL exist, published value in accordance with ASHRAE 34.|
|QA2L||=||Minimum required air flow rate, conversion to other units of measures is permitted, cubic feet per second (m3/s).|
For exact ventilation rates and for refrigerants not listed, the ventilation rate shall be calculated using this equation.