BCU 580 · Edition 11.15
30
5 .1 .3 Test period t
P
Depending on the burner capacity, the tightness of the gas
solenoid valves must be checked in accordance with the rel-
evant application standard, e.g. EN 676, EN 746, NFPA 85
and NFPA 86.
BCU 560..C1
µC
P
13
14
45
47
58
48
p
u
/2
TC
PZ
PZL
PDZ
M
>750°
ϑ
1
2
3
p
u
/2
PZ
V
p1
V1
V2
p
u
p
z
p
d
The test period t
P
is calculated from:
– Opening times t
L
for V1 and V2,
– Measurement times t
M
for V1 and V2.
t
P
[s] = 2 x t
L
+ 2 x t
M
5 .1 .4 Opening time t
L
Standard EN 1643:2000 allows a maximum opening time of
3 s for the tightness test if the main gas valves are actuated
directly. If gas can flow into the combustion chamber when a
valve is opened, the gas volume must not exceed 0.083 % of
the maximum flow rate.
5 .1 .5 Measurement time t
M
The sensitivity of the tightness control in the BCU can be ad-
justed for each individual system by adapting the measure-
ment time t
M
. The longer the measurement time t
M
, the greater
the sensitivity of the tightness control. The measurement time
is set using parameter 56 to a value between 3 and 3600 s –
see page 90 (Measurement time Vp1).
The required measurement time t
M
is calculated from:
Inlet pressure p
u
[mbar]
Leakage rate Q
L
[l/h]
Test volume V
p1
[l]
Calculation of the test volume – see page 30 (Test vol-
For one test volume V
p1
between 2 gas solenoid valves
Adjustable using parameter 56
t
M
[s] =
(
2 x p
u
x V
p1
)
Q
L
For a large test volume V
p1
with reduced testing time
Adjustable using parameter 56
t
M
[s] =
(
0.9 x p
u
x V
p1
)
Q
L
Conversion into US units – see page 117 (Converting units)
Leakage rate
The BCU tightness test ensures that the leakage rate Q
L
is
< 0.1% of the maximum flow rate Q
(N)max.
.
Leakage rate Q
L
[l/h]
=
Q
(N)max.
[m
3
/h] x 1000 [l/h]
1000 x 1 [m
3
/h]
Test volume V
p1
Valve proving system > Tightness test
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