ENGLISH-36
Refrigerant piping work
Vacuum drying
f
Use the tools for R-32 only to prevent the inflow of foreign substances and resist
against the internal pressure.
f
Use the vacuum pump with the check valve to prevent pump oil from flowing
backward while the vacuum pump is stopped suddenly.
f
Use the vacuum pump that can be vacuumed up to 666.6Pa(5 mmHg).
f
Close the service valve of the liquid side pipe, gas side pipe completely when
performing air tightening test or vacuum drying.
Pressure Increase
No
Connect the manifold gauge to the liquid
pipe and gas pipe.
Vacuum the liquid pipe and gas pipe
using the vacuum pump.
Make sure to install check valve to prevent pump oil from
flowing into the pipe.
Vacuum those pipes for more than 2 hours
and 30 minutes.
The time of vacuum drying may differ depending on the
length of the pipe or outdoor temperature.
Perform vacuum drying for at least 2 hours and 30 minutes.
Close the valve after checking the vacuum
gauge pressure has reached at -100.7 kPa
(gauge pressure).
Check the vacuum pressure using the vacuum gauge.
Check whether the pressure is maintained
as -100.7 kPa (gauge pressure), 5 torr. for
an hour.
Charging additional refrigerant according
to piping length
Yes
Check the gas leak.
Vacuum destruction due to the
moisture inside the pipe
• Apply pressure with Nitrogen gas of
0.05 MPa (gauge pressure).
Perform vacuum drying again up to
-100.7 kPa (gauge pressure), 5 torr (for
2 hours or longer) and evaluate the
vacuum
Pressure Increase
Yes
No
• If the pressure rises in an hour, either water remains inside the pipe, or there will be a leak.
CAUTION
Vacuum
pump
Manifold gauge
High
pressure
side
Low pressure side
Service port
Gas side
pipe
Liquid
side pipe
