Honeywell BCU 460, Technical Information, Page: 42 / 145

BCU 460, BCU 465 · Edition 11.19 42
tL = A059
tM = A056
pZ >
pu
2
+
–
OK
V1
V1
V1 OK
V2
V1
V2
pZ >
pu
2
+
–
tL = A059
tM = A056
V2
V2
tL = A059
tM = A056
+
–
V2 OK
pZ >
pu
2
V1 OK V1
V2
V2
V2
pZ >
pu
2
+
–
tL = A059
tM = A056
V1
V1
pZ >
pu
2
+ –
PZ
V1 V2
p
z
p
u
/2
Program A Program B
START
Valve proving system
6 .1 .2 Program sequence
The tightness test starts by checking the external pres-
sure switch. If pressure p
Z
> p
u
/2, program A starts.
If pressure p
Z
< p
u
/2, program B starts, see page 43
(Program B).
Program A
Valve V1 opens for the opening time t
L
set in parame-
ter A059. V1 closes again. During the measurement time
t
M
, the tightness control checks the pressure p
Z
between
the valves.
If pressure p
Z
is less than half the inlet pressure p
u
/2,
valve V2 is leaking.
If pressure p
Z
is greater than half the inlet pressure p
u
/2,
valve V2 is tight. Valve V2 is opened for the set opening
time t
L
. V2 closes again.
During the measurement time t
M
, the tightness control
checks the pressure p
Z
between the valves.
If pressure p
Z
is greater than half the inlet pressure p
u
/2,
valve V1 is leaking.
If pressure p
Z
is less than half the inlet pressure p
u
/2,
valve V1 is tight.
The tightness test can only be performed if the pres-
sure p
d
downstream of V2 is around atmospheric pres-
sure and the volume downstream of V2 is at least 5 ×
higher than the volume between the valves.
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