Gas detectors for machinery / mechanical room safety, need to adhere to ASHRAE 15 and 34, EN 378 and CSA-B52 compliance. The aim of these safety standards is to give warning to a technician or other commercial building employee before walking into a mechanical or machinery room where the refrigerant gas concentration may exceed safe concentration levels due to a leak. Several of the limiting values of the safety standards are the Occupational Exposure Limit (OEL), Short Term Exposure Limit (STEL) – a 15 minute Time Weighted Average (TWA), Immediate Danger to Life and Health (IDLH), Oxygen Deprivation Limit (ODL)/Acute-Toxicity Exposure Limit (ATEL) and Practical Limit. Extended exposures to HFC or HFO refrigerants can cause adverse cardio and neurological health effects or in higher concentrations, lead to asphyxiation.
| Gas | OEL (ppm) TWA | STEL* (ppm) | IDLH (ppm) | ATEL / ODL | Practical Limit |
|---|---|---|---|---|---|
| R-22 | 1,000 | 1,250 | 59,000 | 0.21 kg/m3 | 0.3 kg/m3 |
| R-134a | 1,000 | 2,000 | 50,000 | 0.21 kg/m3 | 0.25 kg/m3 |
| R-404A | 1,000 | 4,000 | 130,000 | 0.52 kg/m3 | 0.52 kg/m3 |
The gas detector alarm set points, location and number of detection points outlined in the safety standards are typically insufficient for finding the more common, smaller leaks that add up to large annual refrigerant emissions, decreased efficiency and overall safety. For early warning monitoring of refrigerant leaks that provides compliance with EPA Section 608, F-Gas and CARB, gas detectors with a low minimum detection level (MDL) are required.
| Multi-Zone | Single-Zone | MGS-250 | MGS-400 Series | MGS-550 | |
|---|---|---|---|---|---|
| Diffusion |  | | |
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| Aspirated | | | |||
| Minimum Detection Level (MDL) | 1 ppm | 1 ppm | 10 ppm | 50 - 200 ppm typical | 50 - 200 ppm typical |
| Sensor Channels | 16 | 1 | 1 | 1 | 2 |
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