Piping Connections And Valve Operations - Mitsubishi Electric CITY MULTI PURY-M-YNW-A Serie Manual De Instalación

9-5. Piping connections and valve operations

Before heating the brazed sections, remove the gas and oil that are trapped in the pipes.
- Failure to do so may generate fire, resulting in serious injury.
Ventilate the room while servicing the unit.
- If the refrigerant leaks, oxygen deficiency may result. If the leaked refrigerant comes in contact
with a heat source, toxic gas will be generated.
Store pipes indoors, and keep both ends of the pipes sealed until just before making a
flare connection or brazing. (Store elbows and other joints in plastic bags.)
- If dust, dirt, or water enters the refrigerant lines, the refrigerant oil will deteriorate and the
compressor will malfunction.
Keep the service valves closed until refrigerant charging is completed.
- Failure to do so will damage the unit.
Place a wet towel on the service valves before brazing the pipes to keep the temperature of
the valves from rising above 120ºC (248ºF).
- Failure to do so may result in equipment damage.
Keep the flame out of contact with the cables and metal sheet when brazing the pipes.
- Failure to do so may result in burnout or malfunction.
Braze the pipes with a nitrogen purge to avoid oxidation.
- Oxidized flux inside the refrigerant pipes will cause the refrigerant oil to deteriorate and cause
the compressor to malfunction.
9-5-1. Removing the pinched connecting pipes
The unit is shipped with the pinched connecting pipes attached to the high- and low-pressure side service valves to
prevent gas leakage.
Take the following steps ① through ③ to remove the pinched connecting pipes before connecting refrigerant pipes to
the outdoor unit.
① Check that the service valves are fully closed (turned clockwise all the way).
② Remove the gas in the pinched connecting pipes, and drain out all the refrigerant oil. (See Ⓔ below.)
③ Remove the pinched connecting pipes. (See Ⓕ below.)
<A> <B>
Ⓓ
Ⓔ
WT08842X01
<A> Refrigerant service valve (high-pressure/brazed)
<B> Refrigerant service valve (low-pressure/brazed)
Ⓐ Valve shaft
Ⓐ
The unit is shipped with the valve closed. Keep the valve closed while connecting pipes or
evacuating the system. Open the valve upon completion of this work.
Ⓑ Turn the shaft counterclockwise as far as it will go (90˚) to open the valve, and clockwise to
close it.
Ⓒ
Ⓑ Stopper pin
Prevents the shaft from turning 90˚ or more.
Ⓒ Service port
Ⓕ
Through the service ports, you can charge refrigerant, remove the gas in the pinched
connecting pipes, or evacuate the system.
Ⓓ Cap
Remove the cap before turning the shaft. Put the cap back on upon completion of all work.
Ⓔ Severed section of the pinched connecting pipe
Ⓕ Brazed section of the pinched connecting pipe
GB-27