Hoshizaki Modular Cubelet Serenity Series Service Manual page 43

1. Refrigerant Recovery
Using proper refrigerant practices, recover the refrigerant. Recover via the service valves.
Store the refrigerant in an approved container. Do not discharge the refrigerant into the
atmosphere.
2. Brazing
• R-404A itself is not flammable at atmospheric pressure and temperatures up to
176°F (80°C).
• R-404A itself is not explosive or poisonous. However, when exposed to high
temperatures (open flames), R-404A can be decomposed to form hydrofluoric
acid and carbonyl fluoride both of which are hazardous.
• Do not use silver alloy or copper alloy containing arsenic.
1) Braze all fittings while purging with nitrogen gas flowing at a pressure of 3 to 4 PSIG.
• Always install a new drier every time the sealed refrigeration system is opened.
• Do not replace the drier until after all other repair or replacement has been made.
Install the new drier with the arrow on the drier in the direction of the refrigerant
flow.
• When brazing, protect the drier by using a wet cloth to prevent the drier from
overheating. Do not allow the drier to exceed 250°F (121°C).
2) Use an electronic leak detector or soap bubbles to check for leaks. Add a trace of
refrigerant to the system (if using an electronic leak detector), and then raise the
pressure using nitrogen gas (140 PSIG). Do not use R-404A as a mixture with
pressurized air for leak testing.
3. Evacuation and Recharge (R-404A)
1) Attach a vacuum pump to the system. Be sure to connect the charging hoses to both
high and low-side refrigerant service valves.
The vacuum level and vacuum pump may be the same as those for current
refrigerants. However, the rubber hose and gauge manifold to be used for
evacuation and refrigerant charge should be exclusively for POE oils.
2) Turn on the vacuum pump, then open the gauge manifold valves, then open the high
and low-side service valves. Never allow the oil in the vacuum pump to flow backwards.
3) Allow the vacuum pump to pull down to a 29.9" Hg vacuum. Evacuating period depends
on pump capacity.
4) Close the low-side valve and high-side valve on the gauge manifold.
WARNING
NOTICE
IMPORTANT
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