TC · Edition 08.17
30
Function
Test procedure B
If pressure p
z
< p
u
/2, valve V1 is tight. Valve V1 is
opened for the opening time t
L
= 2 s. V1 closes again.
During the measurement time t
M
, the tightness control
checks the pressure p
z
between the valves.
If pressure p
z
< p
u
/2, valve V2 is leaking.
If pressure p
z
> p
u
/2, valve V2 is tight.
The tightness test can only be performed if the pres-
sure downstream of V2 is around atmospheric pressure
and the volume downstream of V2 is at least 5 x higher
than the volume between the valves.
The tightness control TC runs program
A
or
B
depend-
ing on the initial situation. Both valves are checked for
tightness respectively, but only one valve is opened at a
time.
During the test, the TC also checks their fail-safe opera-
tion.
After a brief power failure during the tightness test or
operation, the TC restarts automatically.
+
–
V2
OK
V1
OK
t
L
= 2 s
t
M
+
–
t
M
p
z
>
p
u
2
+
–
V2
V2
V2
p
z
>
p
u
2
V1
OK
V1
V2
OK
V1
V1
t
L
= 2 s
p
u
p
u
p
z
t
W
p
z
>
p
u
2
TEST
V1
V2
PZ
2
Test procedure
A
Test procedure
B
START