2.6.6 Sources of Ignition
There should be no sources of ignition as part of the refrigerating system or equipment.
Electrical Components
Precautions should be taken to avoid the possibility of direct sources of ignition from
exposed electrical contacts. Electrical items that have the potential to produce electrical
sparks during normal operation should receive particular attention to eliminate them as
potential sources of ignition. The following methods can be applied:
Insulate terminals
Locate within appropriate enclosures
Replace with solid state type components
Replace with explosion proof components
Locate externally
Providing such items only comprise of solid state parts or have casings which are solid
encapsulated or otherwise sealed or are located externally to casing of the refrigerant
containing parts then adequate precautions as required above are normally achieved.
Motors, including fans, pumps and compressors should be of brush less design so as not
to cause potential sparks.
Components to consider as possible sources of ignition are:
- On/off manual switches - Liquid level switch - Condensate pump switch
- Thermostats - Flow switches - Fan speed controllers
- Pressure switches - Start relays - Humidity controllers
- Oil differential switches - Thermal overload relays - Programmable controllers
- Fan delay switches - Potential relays - Defrost timers/switches
- Contactors - Universal relays - Time switches/relays
- Isolator switches
NOTE: This list is not exhaustive.
If the refrigerant charge exceeds 2.5 kg (5.5 lb) in any one refrigerant circuit then the
selection of electrical apparatus and its installation should be in accordance with the
relevant Provincial, Municipal or State requirements.
In machinery rooms it is sufficient to fit leak detection equipment which isolates all plant
room electrical via a contactor, upon detection of refrigerant. The detection device
should also initiate ventilation with an appropriate extract system from a separate
dedicated power supply.
Hot surfaces
Parts of refrigerating machines whose surfaces could become excessively hot shall be
avoided. All components that could come into contact with released refrigerant shall
have a maximum surface temperature not higher than 100ºC (212ºF) below the auto-
ignition temperature of the refrigerant used. Auto-ignition temperatures for various
refrigerants are provided in Table 2.3.
2.6.7 Pipe work Installation
Pipe work installation should be done in accordance with the requirements for the
particular region that the installation is being completed in.
Duracool Refrigerants Inc. 17
