– 38 –
Gauge manifold
[ Cylinder with siphon ]
[ Cylinder without siphon ]
OUTDOOR unit
Gauge manifold
OUTDOOR unit
Refrigerant
cylinder
Electronic
balance
Refriger
ant
cylinder
Electronic
balance
Siphon
1) Be sure to make setting so that liquid can be charged.
2) When using a cylinder equipped with a siphon, liquid can be charged without turning it upside down.
It is necessary for charging refrigerant under condition of liquid because R410A is mixed type of refrigerant.
Accordingly, when charging refrigerant from the refrigerant cylinder to the equipment, charge it turning the
cylinder upside down if cylinder is not equipped with siphon.
R410A refrigerant is HFC mixed refrigerant.
Therefore, if it is charged with gas, the
composition of the charged refrigerant changes
and the characteristics of the equipment varies.
Fig. 7-4-2
7-5. Brazing of Pipes
7-5-1. Materials for Brazing
1. Silver brazing filler
Silver brazing filler is an alloy mainly composed
of silver and copper.
It is used to join iron, copper or copper alloy, and
is relatively expensive though it excels in solder-
ability.
2. Phosphor bronze brazing filler
Phosphor bronze brazing filler is generally used
to join copper or copper alloy.
3. Low temperature brazing filler
Low temperature brazing filler is generally called
solder, and is an alloy of tin and lead.
Since it is weak in adhesive strength, do not use
it for refrigerant pipes.
1) Phosphor bronze brazing filler tends to react
with sulfur and produce a fragile compound
water solution, which may cause a gas
leakage. Therefore, use any other type of
brazing filler at a hot spring resort, etc., and
coat the surface with a paint.
2) When performing brazing again at time of
servicing, use the same type of brazing filler.
7-5-2. Flux
1. Reason why flux is necessary
• By removing the oxide film and any foreign
matter on the metal surface, it assists the flow
of brazing filler.
• In the brazing process, it prevents the metal
surface from being oxidized.
• By reducing the brazing filler's surface tension,
the brazing filler adheres better to the treated
metal.
