Panasonic MDF-DU502VH, Руководство по обслуживанию

Страница: 46 / 78

2.2 Preparation for gas welding
Preparation
：
Flameproof sheet, tools, nitrogen cylinder, charge hose, branching instrument
Procedure : Pull the welded part as far as possible from the product and cover the periphery
with a flameproof sheet as necessary.
In order to prevent oxide film of pipe inside during welding, a nitrogen cylinder is
connected to the low pressure side service valve (SVL)
Replace the nitrogen in the piping. (Nitrogen substitution: provided secondary
pressure is 0.5 to 0.7 MPa) At this time,
Remove the valve in the check valve. (Outlet of nitrogen)
Note
：
Insulation materials are easy to ignite, be sure to cover with fireproof sheets.
The flow rate of nitrogen may be small (to the extent that it feels a little with the skin).
2.3 Piping connection by gas welding
Preparation: gas welding machine, exclusive lighter, silver braze, flux piping tool
(Cutter, reamer, bender, flare tool, expander, wrench, mirror, light etc.)
Welding cooling product (water-filled container, waste etc.),
Weld protective product (leather gloves, goggles, flameproof sheets, steel plates,
etc.)
Procedure: Take care not melt the pipe, heat it so that a braze melts around the connection,
and then braze to it. Check the brazed state with a mirror, light, etc.
When using silver wax, apply flux to the place where you usually braze.
Note: Forced cooling immediately after brazing heating adversely affects the structure of
copper metal. Please leave it for about 2 minutes and then apply wet cloth.
2.4 Refrigeration circuit leak check
Preparations: Leak check spray (liquid detergent can also be substituted)
Procedure: Continue with nitrogen replacement as it is, install a valve in the check valve,
and perform a leak check of the entire unit circuit.
(Nitrogen replacement: provided that the secondary pressure is 0.5 to 0.7 MPa)
Note: Use a leak check spray to check the gas leak at the replacement (welding)
point.
Valve sate
open shut
SVL
○
N
it
ro
g
e
n
c
y
lin
d
e
r
Check valve
High pressure
service valve
Low pressure
service valve
SVL
-43-