PIETRO FIORENTINI NORVAL, Installation, Commisioning And Maintenance Instructions

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TECHNICAL MANUAL MT044
15
The regulator must be installed in the line with the arrow on the body pointing in the gas flow direction .
It is indispensable for good regulation for the position of the downstream pressure take-offs and the speed of the
gas at the take-off point to respect the values given in tables 3 and 4 (positioning) and 5 (speed).
The pressure regulator, when installed on a reducing station, shall be installed at least according to the
requirements of standard EN 12186.
All venting connections shall be connected as required by above mentioned standard.
The following is recommended so as to prevent the accumulation of impurities and condensate in the lines of the
pressure take-offs:
a) the lines themselves must slope down towards the downstream piping with a slope of about 5-10%;
b) the connectors on the piping must always be welded on the top of the piping itself and there must be no burr
or inward protrusions in the hole in the piping.
NB. WE RECOMMEND NOT TO PUT ON/OFF VALVES ON THE IMPULSE TAKE-OFFS
TAB. 5
The speed of the gas must not exceed the following values in the piping downstream from the regulator:
Vmax = 25 m/s for 1,5 < Pa < 4 bar
Vmax = 20 m/s for 0,5 < Pa < 1,5 bar
Vmax = 15 m/s for Pa < 0,5 bar
DOWNSTREAM VOLUME REQUIRED FOR INSTALLATION
In the case of a service regulator of the ON-OFF type (stopping or starting of burners), you should remember that
though the NORVAL apparatus is classified as being of the fast reaction type, it requires an appropriately
dimensioned volume of gas between the apparatus itself and the burner so as to partly absorb the pressure swings
caused by fast flow rate variations.