2.8.2 Air tight test and vacuum drying method
After finished piping work, carry out air tight test and vacuum drying.
<Air tight test>
If moisture might enter the piping, follow below.
(I.e., if doing work during the rainy season, if the actual work takes long enough that
condensation may form on the inside of the pipes, if rain might enter the pipes during
(1) After performing the vacuum drying for two hours, pressurize to
0.05 MPa (i.e., vacuum breakdown) with nitrogen gas, then depressurize down to –100.7 kPa
(2) If the pressure does not reach –100.7 kPa even after depressurizing for at least two hours,
After vacuum drying, maintain the vacuum for an hour and make sure the pressure does not rise
by monitoring with a vacuum gauge.
Pressurize the liquid and gas pipes to 4.0MPa (40bar) (do not pressurize more than 4.0MPa
(40bar)). If the pressure does not drop within 24 hours, the system passes the test.
If there is a pressure drop, check for leaks, make repairs and perform the airtight test again.
Evacuate the system from the liquid and gas pipes by using a vacuum pump for more than 2
hours and bring the system to
–100.7kPa or less. After keeping the system under that condition for more than 1 hour,
check if the vacuum gauge rises or not. If it rises, the system may either contain moisture
inside or have leaks.
for an hour using the vacuum pump (vacuum drying).
repeat the vacuum breakdown - vacuum drying process.
Heat Pump 60Hz (RXYQ5~54P)