Section – Pressure Test (Strength Test) with OFDN
Steps recommended
No
Where Activities
1
Carry out all intended works without hurry and
THINK BEFORE ACTING!
2
AC system “OFF“ (unplugged) and emptied from HC refrigerant.
3
Arrange your tools and equipment connections as indicated on page 94.
The pressure adjusting handle (screw) of the pressure regulator is back-
seated. The cylinder valve and the pressure regulators outlet-valve to the
OFDN transfer hose (N) is closed!
4
N, L
Ensure that the Nitrogen transfer hose with the connection at the suction
line service port “L” consists of a core depressor to open the service port
inner core valve during connection.
5
N, L
Connect the OFDN cylinder with transfer hose N to the service port of the
outdoor units low-side stop valve L.
6
H, L
Open the outdoor units low-side and high-side stop valves.
7
Open the OFDN cylinder valve.
8
Adjust the pressure regulators pressure adjusting handle (screw) to about
10 bar (150 PSI) shown at the delivery pressure gauge
9
Open slowly the pressure regulators outlet-valve.
10
OFDN is now transferred into the complete AC system. Continue the
transfer of Nitrogen until there is no further flow audible (pressure equali-
sation) and 10 bar (150 PSI) is indicated. Watch the gauge for pressure
loss!
11
Slowly turn the pressure regulators adjusting handle to increase the sys-
tem pressure in stages of about 3 bar (45 PSI) at a time and listen for any
audible pressure loss at every step of adjustment. Watch the gauge!
12
When the pressure test value of 44 bar (4.4 MPa) is reached, close the
pressure regulators outlet-valve and the cylinder valve. Listen for any au-
dible pressure loss and watch and note the pressure at the gauge. Wind
the pressure regulators pressure adjusting handle in back-seated position
(pressure regulator is now discharged).
13
Carry out a Leak Test by covering potential brazed joints, mechanical
unions or piping, with the weak soapy water solution and carefully search
for bubbles. Additionally, the amount of discharging Nitrogen will indicate
a leak by creating a venting noise. Repeat the Bubble Test until you are
confident that no leaks exist. Use a small mirror for places that are difficult
for assessment.
14
N, L
Remove the OFDN transfer hose from the service port.
15
Carefully open the service ports Schrader valve using a valve “pin” de-
pressor (e.g. a small screw-driver) and blow-out the Nitrogen charge. If
necessary hold a piece of old cloth (or paper) into the flow stream to
keep eventually escaping oil from the system. Do not inhale the escap-
ing gas. Ensure ventilation of the work space during gas venting. Leave
a slight overpressure in the system.
16
If a leak was found in step 12, repair the leak or replace the leaky
component and continue with steps 5 and 7 to 14.
17
H, L
Close the outdoor units low-side and high-side stop valves (front-seated
position)
Pressure Test (Strength Test) with OFDN — Course of activities sequences
N
The Pressure
Test Value for
the AC system
(Strength Test)
is at 1.1 times of
the Maximum
Allowable Pres-
sure (PS) which
is indicated at
the outdoor units
data plate.
Pressure Test
Value = 1.1 x
PS (40 bar) =
44 bar (4.4 MPa)
Ensure that no
unauthorised
persons are
within vulner-
able locations
in case of an
inadvertent
pressure burst.
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