Lamtec ETAMATIC - Valve Leakage Test Flow Chart; Calculation Example

65
8 Control Mode
8.2.2 Calculation Example
An (approximate) formula for calculating the valve leakage test monitoring facility is summa-
rised below:
This means for a maximum gas flow rate of 50 m
3
/h the formula is:
Insert numerical value in mbar for Δp.
The formula for a gas flow rate of Q > 50 m
3
/h is:
Insert the numerical value in m
3
/h for Q and in mbar for Δp .
A. Assuming: ∆p = 20 mbar, gas flow rate < 50 m
3
/h
B. Assuming: ∆p = 20 mbar, gas flow rate = 200 m
3
/h
Definitions: GDW: gas pressure monitor
V1: gas-side safety shut-off device
V2: burner-side safety shut-off device
P
B
barometric air pressure < 1000 mbar
P
SU
lower GDW switching point (falling)
P
SO
upper GDW switching point (rising)
p = P
SO
- P
B
GDW switching difference
PG gas flow pressure (supply pressure before V1)
V
P
volume of gas line tested
V
L
leakage quantity
V
Lmax
maximum admissible leakage quantity (limit value)
t
P
testing time (30 s adjustable, default = 20 s)
i.e. the gas line you want to test must not
exceed 20,8 dm
3
, for being able to detect
the required leakage quantity.
i.e. the gas line you want to test must not
exceed 83,3 dm
3
, for being able to detect
the required leakage quantity of 200 dm
3
/h.