Brazing - Hoshizaki KM-500MAH Service Manual

4) Close the Low-side Valve and High-side Valve on the Service Manifold.
5) Disconnect the Vacuum Pump, and attach a Refrigerant Service Cylinder to the High-side
line. Remember to loosen the connection, and purge the air from the Hose. See the
Nameplate for the required refrigerant charge. Hoshizaki recommends only virgin refriger-
ant or reclaimed refrigerant which meets ARI Standard No. 700-88 be used.
6) A liquid charge is recommended for charging an R-404A system. Invert the service
cylinder. Open the High-side, Service Manifold Valve.
7) Allow the system to charge with liquid until the pressures balance.
8) If necessary, add any remaining charge to the system through the Low-side. Use a
throttling valve or liquid dispensing device to add the remaining liquid charge through
the Low-side access port with the unit running.
9) Close the two Refrigerant Access Valves, and disconnect the Hoses and Service Mani-
fold.
10) Cap the Access Valves to prevent a possible leak.

2. BRAZING

1. Refrigerant R-404A itself is not flammable at atmospheric pressure and
temperatures up to 176° F.
2. Refrigerant 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.
3. Always recover the refrigerant and store it in an approved container. Do not
discharge the refrigerant into the atmosphere.
4. Do not use silver alloy or copper alloy containing Arsenic.
5. Do not use R-404A as a mixture with pressurized air for leak testing.
Refrigerant leaks can be detected by charging the unit with a little refriger-
ant, raising the pressure with nitrogen and using an electronic leak detector.
Note: All brazing-connections inside the Evaporator Case are clear-paint coated.
Sandpaper the brazing connections before unbrazing the components. Use a
good abrasive cloth to remove coating.
DANGER
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