54
11.1.4.7
Air-Tightness Test on the
Refrigerating System
Before system charged with refrigerant and before the
refrigerating system in put into operation, below site
test procedure and acceptance criteria shall be
verified by the certified technicians, and/or the
installer:-
Step 1: Pressure test for refrigerant leak detection:
1) Steps for pressure test, in accordance to ISO
5149.
2) Evacuate the system from refrigerant before the
leak test, attach the gauge manifold set correctly
and tightly. Charging hose of Low side connect to
Gas side. (Charging hose of High side connect to
Liquid side if applicable.)
3) Adjust the knob on the service valves, and
regulator on the gauge set, so that test gas can be
inserted through the centre manifold of the gauge
set.
4) Insert Nitrogen gas into the system through the
centre manifold and wait until the pressure within
the system to reach about 1MPa (10 BarG) wait
for a few hours and monitor the pressure reading
on the gauges.
5) Please note that the system’s pressure may rise
slightly if the test is carried out on mid day, due to
temperature rise. The inverse may happen when
there is temperature drop at night.
However, this variation will be minimal.
6) Waiting time depends on the size of the system.
Larger systems may require 12 hours of waiting
time. Leak detection within smaller system can be
achieved in 4 hours.
7) Check if there is a constant pressure drop. Move
to next step “Step 2: Refrigerant leak detection...”
if there is any pressure drop. Otherwise, release
the Nitrogen gas and, move to “Step 3: Vacuum
test”.
8) Next, insert a small amount of same refrigerant
into the system through the centre hose, until the
pressure reaches about 1MPa (10 BarG).
7
N
2
R-###
3
4
8
2
2
(Low/Gas)
pressure gauge
(High/Liquid) pressure gauge
An example illustrations of setup for
refrigerant leak detection.
Step 2: Refrigerant leak detection through Electronic
halogen leak detector and/or ultrasonic leak detector:
1) Use any one of below detector to check leaking.
i.
Electronic halogen leak detector.
a. Switch on the unit.
b. Cover the test area from direct draft.
c. Pass the detection probe near test area
and wait for audible and visible signals.
ii.
Ultrasonic Leak Detector
a. Make sure the area is quiet.
b. Switch on the ultrasonic leak detector.
c. Move the probe along your air
conditioning system to test for leaks, and
mark for repair.
2) Any leak detected at this level shall be repaired
and retested, starting from “Step 1: Pressure test”.
NOTE:
-
Always recover the refrigerant and Nitrogen gas
into recovery cylinder after completion of a test.
-
You must use the detection equipment with
Detectable Leak Rate of 10
-6
6 Pa.m
3
/s or better.
-
Do not use refrigerant as test medium for system
with total refrigerant charge more than 5kg.
-
Test shall be performed with dry Nitrogen or
another non-flammable, non-reactive, dried gas.
Oxygen, air or mixtures containing them shall not
be used.
Step 3: Vacuum test:
1) Perform Vacuum test to check leak / moisture if
present.
2) Refer to section “EVACUATION OF THE
EQUIPMENT” to vacuum gas out of the air
conditioning system.
3) Wait for a few hours, depending on the size of the
refrigerating system and monitor the pressure rise.
If the pressure rises until 1 bar absolute, then
there is leak.
If the pressure rises, but it is lower than 1 bar
absolute, then moisture is present.
Vacuum pump
Handle
(Low/Gas)
pressure gauge
(High/Liquid) pressure gauge
3
2
2
An example illustrations of setup for
refrigerant leak detection.
