S200 Series
4
Overpressure Protection
The recommended pressure limitations are stamped on
the regulator nameplate. Some type of overpressure
protection is needed if the actual inlet pressure exceeds the
maximum operating outlet pressure rating. Overpressure
protection should also be provided if the regulator inlet
pressure is greater than the safe working pressure of the
downstream equipment.
Regulator operation below the maximum pressure limitations
does not preclude the possibility of damage from external
sources or debris in the line. The regulator should be inspected
for damage after any overpressure condition.
Startup
The regulator is factory set at approximately the midpoint of
the spring range or the pressure requested, so an initial
adjustment may be required to give the desired results. With
proper installation completed and relief valves properly
adjusted, slowly open the upstream and downstream shutoff
valves.
Type VSX-2 Startup
The Type VSX-2 is shipped in the tripped position and will
need to be reset. If the Type VSX-2 is a high trip only, it can be
reset before starting the regulator. If the Type VSX-2 is a high
and low trip, the regulator will have to be started and the
downstream system pressurized before the Type VSX-2 can
be reset.
Adjustment
To change the outlet pressure, remove the closing cap or
loosen the locknut and turn the adjusting screw clockwise
to increase outlet pressure or counterclockwise to decrease
pressure. Monitor the outlet pressure with a test gauge
during the adjustment. Replace the closing cap or tighten
the locknut to maintain the desired setting.
Type VSX-2 Trip Adjustment
Note
An adjustment tool is included with the Type VSX-2.
Use only this tool to make adjustments to the unit.
To make adjustments, the overpressure trip spring
is found under the outer adjusting screw and the
underpressure trip spring is found under the inner
adjusting screw.
To adjust the Overpressure Trip Spring:
1. Adjust the overpressure trip setting to its maximum
compression.
2. If present, adjust the underpressure spring to its
minimum compression.
3. Backpressure the unit with the desired trip pressure.
4. Reduce the overpressure trip spring compression until
the Type VSX-2 trips.
To adjust the Underpressure Trip Spring:
1. Adjust the underpressure trip spring back to its minimum
compression.
2. Backpressure the unit with the desired trip pressure.
3. Increase the underpressure trip spring compression until
the Type VSX-2 trips.
Taking Out of Service (Shutdown)
To avoid personal injury resulting from sudden
release of pressure, isolate the regulator from all
pressure before attempting disassembly.
Figure 1.
Minimum Inlet Pressure Required to Prevent Shutoff
on all Sizes of S204, S204H, S206, and S206H Regulators at
Indicated Flow
FLOW RATE, SCFH OF 0.6 SPECIFIC GRAVITY NATURAL GAS
FLOW RATE, m
3
/h(n) OF 0.6 SPECIFIC GRAVITY NATURAL GAS
50
40
30
20
10
0
3.0
2.0
1.0
0
0
1000
2000
3000
4000
5000
6000
7000
8000
MINIMUM INLET PRESSURE, PSIG
MINIMUM INLET PRESSURE,
bar
0
26.8
53.6
80.4
107
134
160
188
214
1-INCH (25,4 mm)
SEAT RING
1/2-INCH (12,7 mm)
SEAT RING
5/8-INCH (15,9 mm)
SEAT RING
1-3/16-INCH (30,2 mm)
SEAT RING
