PART I: SPECIFICATIONS
15
Pressure in the Network / gas flow rate curves(LPG)
Combustion head gas pressure curves
Combustion head gas pressure depends on gas flow and combustion chamber backpressure. When backpressure is subtracted, it
depends only on gas flow, provided combustion is properly adjusted, flue gases residual O2 percentage complies with “Recommended
combustion values” table and CO in the standard limits). During this stage, the combustion head, the gas butterfly valve and the
actuator are at the maximum opening. Refer to Fig. 4, showing the correct way to measure the gas pressure, considering the values of
pressure in combustion chamber, surveyed by means of the pressure gauge or taken from the boiler’s Technical specifications.
Fig. 4
Note: the figure is indicative only.
Key
1
Generator
2
Pressure outlet on the combustion chamber
3
Gas pressure outlet on the butterfly valve
4
Differential pressure gauge
Measuring gas pressure in the combustion head
In order to measure the pressure in the combustion head, insert the pressure gauge probes: one into the combustion chamber’s
pressure outlet to get the pressure in the combustion chamber and the other one into the butterfly valve’s pressure outlet of the burner.
On the basis of the measured differential pressure, it is possible to get the maximum flow rate: in the pressure - rate curves (showed on
the next paragraph), it is easy to find out the burner’s output in Stm
3
/h (quoted on the x axis) from the pressure measured in the
GAS P
R
ES
SURE IN
THE NETWORK mbar
R75A L-.. / P75A L-..
Gas rate Stm
3
/h
ATTENTION: the gas rate value is quoted on the x-axis, the related network pressure is quoted on the y-axis
(pressure value in the combustion chamber is not included). To know the minimum pressure at the gas train inlet,
necessary to get the requested gas rate, add the pressure value in the combustion chamber to the value read on
the y-axis.
1
2
4
3