ITRON RB 4700 Serie Inbetriebnahmeanleitung Seite 34

SSV 8500
(for RB 4700 models with integrated SSV 8500)
Operating principle of the shut-off valve
Theshut-offdeviceisasafetydevicethatgoesoff
whenthepressurevalueinthedownstreampipe
increasesordecreasesbeyondtheprefixedcali-
brationvalues,cuttingautomaticallytheflowofthe
gas
Shut-off valve with screw reset
Thesedeviceconsistsofavalvebody10,acontrol
head,adiaphragmassembly4-15andastem–
valve plug assembly12 –18, which remain in a
balancedpositionthroughamechanicalballsys-
temTheshut-offvalveistriggeredwhenthepres-
34 34
surevalueinthecontrolchamber5,thatfromthe
downstreampipeflowintothischamberthrough
theimpulseintake14,increasesordecreasesbe-
yondtheestablishedpressurevalues,thusmoving
fromitsbalancingpositionthediaphragmassem-
bly4– 1 5Thestem 1 8connectedtothevalveplug
12triggersundertheforceofthespring 1 3,coming
immediatelyintocontactwiththevalve8cutting
automaticallytheflowofthegas
NOTE: The schematic section refers to a safety
valve installed of series 8500, but the operating
principle is valid even for other safety valves in-
stalledofseries8200and8300
Item Description
1
2
3
4
5
6
7
8
9
10 Valvebody
1 1 Outletchamber
12 Valveplug
13 Valveplugspring
14 Diaphragmplate
15 Impulseintake
16 Balls
1 7 Maxcalibrationspring
18 Stem
19 Cover
20 Screwingring
21 Mincalibrationspring
Screwingring
Cover
Vent
Diaphragm
Motorisationchamber
Flange
Valveplugplate
Valveorifice
inletchamber