Honeywell BCU 370 - Program Sequence

BCU 370 · Edition 01.19 30
Function
3.3.1 Program sequence
The program flow chart explains the
process during the TEST phase.
After start-up the waiting time t
W
starts to elapse. Then either the left
or right path is executed.
– If the interspace pressure p
Z
is
greater than half of the inlet pres-
sure p
u
/2 after the waiting time
t
W
, V2 is tight. V2 is opened for a
duration of 3 seconds to vent the
interspace. Then the measure-
ment time t
M
starts to elapse. If
no interspace pressure can be
measured after this time, V1 is
also tight. Both valves have thus
been checked.
– If no interspace pressure p
Z
can
be measured after the waiting
time t
W
, V1 is tight. Then V1 is
opened for 3 seconds to fill the
space between the valves. Then
the measurement time t
M
starts
to elapse. If a pressure can be
measured in the interspace after
this time, V2 is also tight. Both
valves have thus been checked.
▼
V1 V2
p
u
p
z
START
t
W
p
Z
>
p
u
2
t
L
= 3 s
t
M
+
–
+
–
t
L
= 3 s
t
M
p
Z
>
p
u
2
+
–
TEST
V2
I ➔ 0
V2
V2
OK
V2
0 ➔ I
p
Z
>
p
u
2
V1
OK
V1 V2
OK
V1
I ➔ 0
V1
0 ➔ I
V1
OK