BCU 370 · Edition 01.19
54
Parameters
4 .5 .5 Tightness controll, test period t
P
Parameter 26
BCU..D3 only
Defines the tightness control test period t
P
for the gas
solenoid valves. It can be set to 10, 20 or 30 to 250 sec-
onds.
Depending on the burner capacity, the tightness of the
gas solenoid valves must be checked in accordance
with the relevant application standard, e.g. EN 676,
EN 746, NFPA 85 and NFPA 86.
The sensitivity of the tightness control can be adjusted
individually by adapting the test period t
P
. If a low leak-
age rate Q
L
is to be detected, a long test period t
P
must
be set. The test period t
P
is the sum of the waiting
time t
W
, 3 s opening time t
L
and measurement time t
M
.
The test period t
P
is calculated from the inlet pressure
p
u
[mbar (psig)], the leakage rate Q
L
[l/h (ft
3
/h)] and
the test volume V
P
[l (ft
3
)].
t
P
= 4 x
p
u
[mbar] x V
P
[l]
Q
L
[l/h]
+ 1 s
Leakage rate
The tightness test allows a check to be made for a spe-
cific leakage rate Q
L
. In countries where the standards
and Directives of the European Union are applicable,
the maximum leakage rate Q
L
is 0.1% of the maximum
flow rate Q
(N) max.
[m
3
(ft
3
)/h (n)].
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
P
The test volume V
P
is calculated from the basic vol-
ume V
G
(for 2 valves VG), added to the volume of the
pipe V
M
for each additional metre in length L:
L
V
P
= V
G
+ L
x
V
M
DN
Basic volume V
G
Volume per metre V
M
Litres
Quarts
Litres
Quarts
10
0.01
0.011
0.1
0.11
15
0.07
0.074
0.2
0.21
20
0.12
0.127
0.3
0.32
25
0.2
0.21
0.5
0.53
40
0.7
0.74
1.3
1.37
50
1.2
1.27
2
2.11
65
2
2.11
3.3
3.49
80
4
4.23
5
5.28
100
8.3
8.77
7.9
8.35
125
13.6
14.37
12.3
13
150
20
21.13
17.7
18.7
200
42
44.38
31.4
33.18