3 LEAK TESTING OVERVIEW
11
3
3
LEAK TESTING OVERVIEW
3
3
.
.
1
1
T
T
h
h
e
e
o
o
r
r
y
y
o
o
f
f
L
L
e
e
a
a
k
k
T
T
e
e
s
s
t
t
After a tested part is charged with an air pressure, the resulting change in its internal pressure is measured
to detect a leak. A non-leaking reference part (master) is made available and is charged with a pressure
concurrently with the tested part in Leak Testing. After the air supply is stopped, a high-sensitivity differential
pressure sensor (DPS) detects the pressure change in the tested part resulting from a leak.
3.1.1 Stage Summary
Stages
A Start
After clamping and sealing a tested part, initiate a start signal.
B Charge (CHG) stage
Pressurizes the tested part and the master.
C Balance (BAL) stage
Isolates tested part and master from pressure supply and each
other to let the internal pressure stabilize.
Large leak is detected during this stage as No-Go.
D Detection (DET) stage
Detects small leaks.
E Air blow, Exhaust and
End (DL3, END)
Transmits judgment signal, and exhaust pressure inside the
tested part and master from the exhaust port.
Basic Type Pneumatic Circuit
Timing Chart
Solenoid valve
DL1
Delay
CHG
Charge
DL2
Delay
BAL
Balance
DET
Detection
DL3
Air blow
Exhaust
END
Exhaust
End
SV1
SV2
