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REGULATOR OPERATION
Regulator Operating Principle
The fluid coming from the upstream pipe enters the inlet chamber
(4), passes through the opening of the valve (3) and then expands
in the outlet chamber (18) flowing into the downstream pipe.
The downstream pressure, which from the chamber (18) through
the pipe (17) enters the regulation diaphragm housing (14), exerts
a force on the surface of the diaphragm (9) balancing the Ioad oft
the calibration spring (12), enabling the valve plug (5) to find an
optimum position, ensuring good regulation and the required flow
rate.
The series 3200 pressure regulator is fitted with a balanced
compensation system, which allows constant downstream
pressure regardless of variations of upstream pressure. If during
the operation the flow rate increases, due to a demand, or the
inlet pressure decreases, the pressure values in the chambers
18 and 14 will tend to decrease. Consequently the force of the
spring (12) moves the diaphragm assembly (15) downwards and
by means of the lever system (16) adjusts the position of the
valve plug (5), thus resetting the pressure and the flow rate to the
required values. The reverse occurs when the flow rate demand
decreases.
At zero flow, rate the regulator guarantees full tightness. The
regulator is also fitted with a relief valve built into the diaphragm
bolder assembly (15) which, calibrated by means of the spring
(13), serves to discharge externally, through the vent (10), possible
over-pressure created in the chambers 14 and 18.
The capacity of this valve is limited.
Regulator Calibration
The regulator is supplied with calibration values specified in the
order. If a different outlet pressure is required, select the correct
spring to obtain this set pressure.
Once the suitable spring (12) is installed, proceed as follows:
» to increase the outlet pressure value:
rotate in a clockwise direction the screwing ring (11) until the
required value is read on the downstream manometer;
» to reduce the outlet pressure value:
proceed likewise but rotate the screwing ring in an
anticlockwise direction.
It is recommended to proceed slowly waiting for the pressure to
stabilize after each movement of the screwing ring.
These operations can be done either with the regulator in
operation or with the downstream stop valve closed (ensuring a
small vent is open downstream to give a small flow).
SHUT-OFF VALVE OPERATION
Operating Principle of the Shut-off Valve
The pressure regulator can be fitted with an independent shut-off
valve consisting of a shutoff valve casing (21) and a diaphragm
assembly (29), which controls a mechanical ball system enabIing
the release of the valve.
The shut-off valve is triggered when the pressure value in the
chamber (22) increases or decreases beyond the preset values
established and thus moves the entire assembly(29) from a
balanced position. The stem (27), which is connected to the valve
plug (19) is triggered under the force of the spring and comes
immediately into contact with the orifice (2), cutting automatically
the flow of the fluid.
For series 3211 the shut-off valve operates only for. over-pressure
shutoff; for series 3212 it operates for both over and low-pressure
shut-off.
Adjustment of the Shut-off Valve
If the set values of the shut-off are to be modified, proceed as
follows:
(A) over-pressure shut-off operation:
Rotate the outside shut-off screwing ring in a clockwise
direction to increase the pressure values, or anticlockwise to
reduce it.
(B) low-pressure shut-off operation:
Likewise but on the central shut-of screwing ring.
Resetting of the Shut off Valve
The shut-off valve must be reset only after verifying the reasons
far the intervention and after having re-established normal
operating conditions, proceeding as follows:
(A) close the downstream stop valve;
(B) remove the cover (25), unscrewing it (see fig. B1);
(C) screw it upside down into the stem (23), until it comes into
contact with the cover (see fig. B2);
(D) continue to screw it slowly; this causes the valve to open
slowly and pressure fills the downstream pipe piece;
(E) pull the cover outwards to permit seating of the balls on the
stem: this operation ensure resetting (see fig. B3);
After these operations, screw the cover to its housing (see fig. B4)
and open slowly the downstream valve.
Caution: for safety reasons, the cover must absolutely be
screwed to its housing, as shown in the schematic section.
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