Specifications

4 Instruction 3015-4256
Suggested Location of Sampling Point
At the point of a refrigerant gas leak, the gas is nearly pure. As refrigerant gas is dispersed into the air, the gas
molecules diffuse, causing a dilution of the original concentration. The HGM-SZ measures the gas
concentration at the point the sample is collected. Therefore, if the termination of the collection line is not at the
exact point of the gas leak, then the monitor will read a diluted mixture of refrigerant gas and air.
It should be noted that when refrigerant gas is cold, it is heaver than air and settles below the leak point. When
the gas warms to room temperature, it becomes lighter than air and tends to collect above the leak point.
Consequently, the sampling point should be located as close as possible to the source of a potential leak. If this
is impractical, then the alarm set points should be adjusted to compensate for the dilution of the refrigerant gas.
The HGM-SZ should be mounted outside of the mechanical room or just inside a doorway to the room. This is
the “split architecture design” for safety of the operator. The monitor should be readily accessible for easy visual
monitoring and servicing. The total length of the sample line + exhaust line can be up to 500 ft (152.4 m). If the
area around the monitor is not well ventilated, then an optional exhaust line and purge line can be run to an
outside location. The total length of the exhaust line + the purge line cannot exceed 500 ft (152.4 m).
It may be necessary to perform a “smoke” test of the mechanical room to determine the best monitoring point.
The smoke test would provide the pattern of air currents present in the room.
HGM-SZ Refrigerant Gas Leak Monitor Mechanical Room Placement