Combustibility Of Hfc-134A; Leak Testing; Bulk Delivery And Storage; Filling And Charging Operations - Electrolux EI15IM55GS Service Manual

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Service Information
Always wear protective clothing when there is
a risk of exposure to liquid HFC-134a. Where
splashing is possible, always wear eye protection
and a face shield.

Combustibility of HFC-134a

HFC-134a is nonflammable at ambient
temperatures and atmospheric pressure. However,
tests have shown HFC-134a to be combustible
at pressures as low as 5.5 psig (139.3 kPa
absolute) at 177°C (350°F) when mixed with air
at concentrations generally greater than 60%
volume air. At lower temperatures, higher pressures
are required for combustibility. (HCFC-22 is also
combustible at pressures above atmospheric in the
presence of high air concentrations). Test results
and calculations have shown:
• At ambient temperature, all concentrations
of HFC-134a in air are nonflammable at
pressures below 15 psig (205 kPa absolute).
• Combustible mixtures of air and HFC-
134a will not form when liquid HFC-134a
is pumped into closed vessel if initial
air pressure in vessel is limited to one
atmosphere absolute and final pressure is
limited to 300 psig (2,170 kPa absolute).
If initial air pressure is greater than one
atmosphere, combustible mixtures may form
as tank is filled.
Based on above information, the following
operating practices are recommended:

Leak Testing

• Equipment should NEVER be leak tested
with a pressurized mixture of HFC-134a and
air. HFC-134a may be safely pressured with
dry nitrogen.

Bulk Delivery and Storage

• Tanks should normally be evacuated at start
of filling, and should never be filled while
under positive air pressure.
• Tank pressure should never be allowed to
exceed 300 psig (2,170 kPa) when filling with
HFC-134a. Relief devices on either tanks
or HFC-134a supply system usually prevent
this.
• Tank pressures should be monitored
routinely.
• Air lines should never be connected to
storage tanks.

Filling and Charging Operations

• Before evacuating cylinders or refrigeration
equipment, any remaining refrigerant should
be removed by recovery system.
• Vacuum pump discharge lines should be free
of restrictions that could increase discharge
pressures above 15 psig (205 kPa) and result
in formation of combustible mixtures.
• Cylinders or refrigeration equipment should
normally be evacuated at start of filling,and
should never be filled while under positive air
pressure.
• Final pressures should not exceed 300 psig
(2,170 kPa).
• Filled cylinders should periodically be
analyzed for air (nonabsorbable gas or NAG).

Refrigerant Recovery Systems

Efficient recovery of refrigerant from equipment
or containers requires evacuation at the end of
the recovery cycle. Suction lines to a recovery
compressor should be periodically checked for
leaks to prevent compressing air into the recovery
cylinder during evacuation. In addition, the recovery
cylinder pressure should be monitored, and
evacuation stopped in the event of a rapid pressure
rise indicating the presence of noncondensable
air. The recovery cylinder contents should then
be analyzed for NAG, and the recovery system
leak checked if air is present. DO NOT continue to
evacuate a refrigeration system that has a major
leak.

Thermal Decomposition

HFC-134a vapors will decompose when exposed
to high temperatures from flames or electric
resistance heaters. Decomposition may produce
toxic and irritating compounds, such as hydrogen
fluoride. The pungent odors released will irritate
the nose and throat and generally force people
to evacuate the area. Therefore, it is important to
prevent decomposition by avoiding exposure to
high temperatures.