Fisher EZR Series

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For PRX Series pilots (Figure 26), loosen locknut

(key 2) and turn the adjusting screw into the spring case

to increase (or out of the spring case to decrease) the

downstream pressure. When the required downstream

pressure is maintained for several minutes, tighten the

locknut to lock the adjusting screw in position

and replace the pilot closing cap.

The Restrictor and Damper screws on the PRX Series

pilot control the regulator’s proportional band (droop)

and speed of response. Table 7 includes the appropriate

settings for low ow operation. For additional tuning

follow the steps outlined below:

1. Start with the restrictor screw 1 turn

counterclockwise from fully seated (turn restrictor

fully clockwise then 1 turn counterclockwise) and the

damper screw fully counterclockwise.

2. Turn damper screw clockwise until desired

performance is achieved. This reduces the ow path

of the damper. If the damper becomes fully seated

(no longer able to turn clockwise) and the desired

performance has not been achieved, return the

damper screw to the fully counterclockwise position.

PILOT TYPE

RECOMMENDED TYPE 112

RESTRICTOR SETTINGS FOR LOW

FLOW OPERATION

RECOMMENDED ORIFICE SIZE(S)

FOR LOW FLOW OPERATION

TYPE 112 RESTRICTOR SETTINGS

AND ORIFICE SIZES TO AVOID AT

LOW FLOW

161AY Series Pilots Restrictor Setting of “5” or greater

3/32 or 1/8 in. / 2.38 or 3.18 mm

(3/32 in. / 2.38 mm is standard)

Avoid restrictor setting of “2” or less if

continuous ows are expected to be

less than 5% of maximum capacity

Note: Higher Type 112 restrictor settings will increase proportional band. Adjustment of the Type 112 restrictor will also cause a shift in setpoint. Setpoint should be checked and adjusted

following restrictor setting adjustment.

Table 6. Type 161AY/161AYM Pilot Adjustment Recommendations

Table 7. Type PRX Pilot Adjustment Recommendations

PILOT TYPE

RECOMMENDED TYPE PRX RESTRICTOR AND DAMPER

SCREW SETTINGS FOR LOW FLOW OPERATION

TYPE PRX RESTRICTOR AND DAMPER SCREW

SETTINGS TO AVOID AT LOW FLOW

PRX/120 and PRX/120-AP Series

Restrictor Screw

- 1 turn out (counterclockwise) from fully seated for most

low ows

- 2-1/2 turns out (for ows less than

5% of maximum)

Damper Screw

- Fully out (counterclockwise) from seated for most

low ows

- One turn out (for ows less than 5% of maximum)

Restrictor Screw

- Fully seated (clockwise) or full out

(counterclockwise)

Damper Screw

- Full in (clockwise)

Note: Counterclockwise adjustment of the Type PRX restrictor screw will increase proportional band. Adjustment of the restrictor screw will also cause a shift in setpoint. Setpoint should

be checked and adjusted following restrictor screw adjustment.

Table 5. 161EB Series Pilot Adjustment Recommendations

PILOT TYPE

RECOMMENDED TYPE 112 RESTRICTOR

SETTINGS FOR LOW FLOW OPERATION

TYPE 112 RESTRICTOR SETTINGS TO AVOID

AT LOW FLOW

161EB Series Pilots Restrictor Setting of “5” or greater

Avoid restrictor setting of “2” or less if continuous

ows are expected to be less than 5%

of maximum capacity

Note: Higher Type 112 restrictor settings will increase proportional band. Adjustment of the Type 112 restrictor will also cause a shift in setpoint. Setpoint should be checked and adjusted

following restrictor setting adjustment.

WARNING

The damper screw should not be left in

the fully seated position, as it will lock

the regulator in last position which could

cause incorrect pressure regulation.

3. Turn the restrictor screw an additional turn

counterclockwise from fully seated. This increases

the ow path of the restrictor. If additional tuning

is required, repeat step 2. Follow this method until

desired performance is achieved.

Type 112 Restrictor Adjustment