PIETRO FIORENTINI HBC 975, Manual

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HBC 975
EN
Use, maintenance and warning manual
SLAM-SHUT VALVE | DESCRIPTION AND OPERATION | REV. 00
4.2 - OPERATION
At no pressure, the valve plug (1) is kept in the closed position by the spring (10) and rests on the reinforced gasket (11).
The upstream pressure (Up) reaches the HP2/2 (4) and the upper head (12) of the R44/SS regulator (6) to prevent inap-
propriate resetting of the valve. By acting on the bypass activation button (13), the gas under pressure is filtered and feeds
the AR100 valve (5), which in turn supplies:
• the chamber of the adjustment spring (14);
• the upstream of the R44/SS regulator (6), calibrated at a pressure of 4.5 bar to overcome the force of the closing
spring (15) of the main valve.
Pressing the reset lever (16) acts on the pressure switch coupling system (9), so as to allow, through the 3/2 valve (8):
• the actuator (2) of the slam-shut valve to be pressurised by the R44/SS regulator (6);
• the plug (1) to open.
In the event that the slam-shut valve is required to trip, the pressure switch coupling system acts on the 3/2 valve to:
• discharge the pressure from the actuator (2) into the atmosphere through the 3/2 valve (8);
• allow the spring (10) to bring the plug (1) to the closing position.
1
2
3
4
6
5
7
8
9
11
10
12
13
14 15
16
U
pstream pressUre
D
ownstream pressUre
L
oaDing pressUre
Fig. 4.2. Operation HBC 975