Honeywell Krom Schroder BCU 580 - Program Sequence

BCU 580 · Edition 11.15l 31
Valve proving system
5.1.2 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 32
(Program B).
Program A
Valve V1 opens for the opening time t
L
set in param-
eter 59. 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 pressure p
d
downstream of V2 is around atmospheric pressure and
the volume downstream of V2 is at least 5 × higher than
the volume between the valves.
t
L
= P59
t
M
= P56
p
Z
>
p
u
2
+
–
OK
V1
V1
V1
OK
V2
V1
V2
p
Z
>
p
u
2
+
–
t
L
= P59
t
M
= P56
V2
V2
t
L
= P59
t
M
= P56
+
–
V2
OK
p
Z
>
p
u
2
V1
OK
V1
V2
V2
V2
p
Z
>
p
u
2
+
–
t
L
= P59
t
M
= P56
V1
V1
p
Z
>
p
u
2
+
–
PZ
V1 V2
p
z
p
u
/2
Program A Program B
START
▼