Checking Refrigerant Piping: General Guidelines; Checking Refrigerant Piping: Setup; To Perform A Leak Test; To Perform Vacuum Drying - Daikin VRV IV-S RXYSQ4T8VB Series Installation And Operation Manual

Leak test and vacuum drying
Checking the refrigerant piping involves:
▪ Checking for any leakages in the refrigerant piping.
▪ Performing vacuum drying to remove all moisture, air or nitrogen
in the refrigerant piping.
If there is a possibility of moisture being present in the refrigerant
piping (for example, water may have entered the piping), first carry
out the vacuum drying procedure below until all moisture has been
removed.
All piping inside the unit has been factory tested for leaks.
Only field installed refrigerant piping needs to be checked.
Therefore, make sure that all the outdoor unit stop valves are firmly
closed before performing leak test or vacuum drying.
NOTICE
Make sure that all (field supplied) field piping valves are
OPEN (not outdoor unit stop valves!) before you start leak
test and vacuuming.
For more information on the state of the valves, refer to
Setup" [ 4 23].
refrigerant piping:
14.3.2 Checking refrigerant piping: General
guidelines
Connect the vacuum pump through a manifold to the service port of
all stop valves to increase efficiency (refer to
Setup" [ 4 23]).
piping:
NOTICE
Use a 2-stage vacuum pump with a non-return valve or a
solenoid valve that can evacuate to a gauge pressure of
–⁠ 1 00.7 kPa (−⁠ 1 .007 bar)(5 Torr absolute).
NOTICE
Make sure the pump oil does not flow oppositely into the
system while the pump is not working.
NOTICE
Do NOT purge the air with refrigerants. Use a vacuum
pump to evacuate the installation.
14.3.3

Checking refrigerant piping: Setup

p < p >
A B
g
f
a
d C
N2
b c e
a Pressure reducing valve
b Nitrogen
c Weighing scales
d Refrigerant R410A tank (siphon system)
e Vacuum pump
f Liquid line stop valve
g Gas line stop valve
A Valve A
B Valve B
C Valve C
Valve
Valve A
Valve B
Valve C
Liquid line stop valve
Gas line stop valve
RXYSQ4~6T8V/YB(*)
VRV IV-S system air conditioner
4P482275-1B – 2020.10
"Checking
"Checking refrigerant
State of valve
Open
Open
Open
Close
Close
NOTICE
The connections to the indoor units and all indoor units
should also be leak and vacuum tested. Keep any possible
(field supplied) field piping valves open as well.
Refer to the indoor unit installation manual for more details.
Leak test and vacuum drying should be done before the
power supply is set to the unit. If not, see also the flow
chart earlier described in this chapter (see
piping" [ 4 22]).
the refrigerant
14.3.4

To perform a leak test

The leak test must satisfy the specifications of EN378‑2.
To check for leaks: Vacuum leak test
1 Evacuate the system from the liquid and gas piping to
–⁠ 1 00.7 kPa (–⁠ 1 .007 bar)(5 Torr absolute) for more than 2 hours.
2 Once reached, turn off the vacuum pump and check that the
pressure does not rise for at least 1 minute.
3 Should the pressure rise, the system may either contain
moisture (see vacuum drying below) or have leaks.
To check for leaks: Pressure leak test
1 Test for leaks by applying a bubble test solution to all piping
connections.
2 Discharge all nitrogen gas.
3 Break the vacuum by pressurising with nitrogen gas to a
minimum gauge pressure of 0.2 MPa (2 bar). Never set the
gauge pressure higher than the maximum operation pressure of
the unit, i.e. 4.0 MPa (40 bar).
NOTICE
ALWAYS use a recommended bubble test solution from
your wholesaler.
NEVER use soap water:
▪ Soap water may cause cracking of components, such
as flare nuts or stop valve caps.
▪ Soap water may contain salt, which absorbs moisture
that will freeze when the piping gets cold.
▪ Soap water contains ammonia which may lead to
corrosion of flared joints (between the brass flare nut
and the copper flare).
To check for leaks after charging refrigerant
After charging refrigerant in the system an additional leak test must
be performed. Refer to To check for refrigerant leaks after charging.
14.3.5

To perform vacuum drying

To remove all moisture from the system, proceed as follows:
1 Evacuate the system for at least 2 hours to a target vacuum of
–⁠ 1 00.7 kPa (–⁠ 1 .007 bar)(5 Torr absolute).
2 Check that, with the vacuum pump turned off, the target
vacuum is maintained for at least 1 hour.
3 Should you fail to reach the target vacuum within 2 hours or
maintain the vacuum for 1 hour, the system may contain too
much moisture. In that case, break the vacuum by pressurising
with nitrogen gas to a gauge pressure of 0.05 MPa (0.5 bar)
and repeat steps 1 to 3 until all moisture has been removed.
4 Depending on whether you want to immediately charge
refrigerant through the refrigerant charge port or first pre-charge
a portion of refrigerant through the liquid line, either open the
outdoor unit stop valves, or keep them closed. See
refrigerant" [ 4 24] for more information.
14 Piping installation
"About checking
"To charge
Installation and operation manual
23