Mitsubishi Electric ECOV-X37VA Manuel D'installation page 29

7-5. Connecting pipes
7-5-1. Brazing
• Use a clean copper pipe so as not to allow dirt and water to infiltrate inside the piping system.
• In a corrosive atmosphere, such as where there is high sulfurous acid gas concentration, use silver filler.
• Do not use low-temperature fillers because they do not have sufficient strength.
• When re-brazing, use the same filler material.
• Paint the brazed parts.
• Use an appropriate flux according to the type and shape of the substrate, filler type, and brazing method.
• Do not conduct refrigerant piping work outdoors when raining.
• If the installed pipes are left unconnected to any equipment, braze and seal both ends of the pipes.
• Flux generally contains chloride. Flux staying in the refrigerant circuit will cause sludge to form.
1. When brazing, as shown in the figure below, heat the minimum necessary area to a temperature suitable for
the filler material.
When brazing, supply a flow of an inert gas, such as dry nitrogen gas, through the pipes to prevent formation of oxide
scale.
After finishing piping, keep the nitrogen gas flowing until the pipes have become cool enough to be touched by hand. (Be
careful not to burn hands and fingers.)
After brazing, cool the pipes without using water.
Do not move the brazed pipes until the braze has solidified. (No vibration must be applied.)
2. Completely remove all the flux after brazing.
Stuff something in the gap between the
hose from the cylinder and the pipe to keep
air from entering the pipe.
N
2
Brazed section
cylinder
Brazing the pipe under nitrogen purge
• Ensure that the flame does not touch any surrounding wiring and plates during brazing. Prevent fire by using a metal plate
as a shield and a wet towel.
Contact with flame may cause fire damage and/or failure.
• When using anti-oxidant for brazing, check its components.
(The anti-oxidant must not contain any components that may lead to corrosion of the pipes if it is mixed with refrigerant or
refrigerant oil.)
• The dryer and filters (strainer, etc.) in the unit may be clogged with oxide scale, which shortens the unit life. Clean or replace
the dryer and filters when they are clogged.
• Brazing must be performed by qualified personnel.
Supply a flow of dry nitrogen gas at a
rate of greater than 1 liter/minute (at
the rate you slightly feel the flow).
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WT09614X03_GB