Leakage Test Venting
Leakage test line over roof
Calculation formula An (approximate) formula for calculating the leak test facility is compiled
below:
Definitions: GDW gas pressure monitor
V1 gas-side safety shut-off device
V2 burner-side safety shut-off device
barometric air pressure 1000 mbar
lower switch point (falling) of GDW
upper switching point (rising) of GDW
switch difference of GDW
gas flow pressure (supply pressure before V1)
volume of gas line tested
leakage quantity
maximum admissible leakage quantity (limit)
testing time (30 seconds, fixed)
3
That is, for a maximum gas flow rate of 50 m /h the formula is:
inserting the numerical value for in mbar.
For a gas rate of flow Q of >50 m3/h the formula is:
3
inserting the numerical value for Q in m /h and for in mbar.
3
Examples: A. Assuming: = 20 mbar, gas rate of flow < 50 m /h: i.e. the gas line to be
tested must be no
3
greater than 20.8 dm
in order to be able to detect the leakage quantity demanded
3
B. Assuming: = 20 mbar, gas rate of flow = 200 m /h:
i.e. the gas line to be
tested must be no
3
greater than 83.3 dm
3
in order to be able to detect the leakage quantity demanded of 200 dm /h.
Suggested circuit for venting
the gas line over-roof in
conjunction with the
combustion management system
* If after shut-off the test line is not vented over-roof but is to be burned off
into the combustion chamber, a timer relay with a delayed cut-out of
2 … 5 sec is to be used.
PB »
PSU
PSO
DP = P SO - PSU
PG
VP
VL
VLmax
tP
D
P
D
P
D
P
D
P
31
416
30 [s]
1000 [mbar]
7
3
50 dm /h ;
VP
tP
Dp
PB
7
3
50 [dm /h] ; Y
; (3);
.
.
VP
Dp
Y VP
Dp
3
[dm ]
7
.
; (4);
Dp
3
[dm ]
VP
7
.
.
Q
0,12
.
7
7
Y VP
416
20
3
[dm ]
3
[dm ]
;
;
Y VP
20,8
7
7
Y VP
200
20
3
[dm ]
3
[dm ]
;
;
Y VP
83,3
0,12
.
to burner
Roof venting
from gas line
*K 1
P
Gas min.
Gas valve 2
Gas valve 1
82
83
Relay-Modul
6 60 R 0016
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