Operation, Worcester controls – Flowserve PM15 Pneumatic Valve Positioner User Manual

Page 3

WCAIM2016

PM15 Pneumatic Valve Positioner Installation, Operation and Maintenance Instructions

(

Flow Control Division

Worcester Controls

POSITIONER MOUNTING GUIDE

ACTUATOR

POSITIONER

Actuator

Mounting

(Note 1)

Inline

Cross-Line

Inline

Cross-Line

Failure

Mode

(Note 2)

Fail-Close

Fail-Open

Actuator
Position
(Note 1)

Normal

Inverted

Normal

Rotation

Open

CCW

Positioner

Operation

Direct-Acting

Reverse-Acting

Direct-Acting

Reverse-Acting

Direct-Acting

Reverse-Acting

Direct-Acting

Reverse-Acting

Cam

(Note 3)

Direct-Acting

Reverse-Acting

Direct-Acting

Reverse-Acting

Direct-Acting

Cam Setting

0˚ (Min. Signal)

When Valve is Closed

90˚ (Max.Signal)

When Valve is Closed

0˚ (Min. Signal)

When Valve is Closed

90˚ (Max.Signal)

When Valve is Closed

90˚ (Max.Signal)

When Valve is Open

0˚ (Min. Signal)

When Valve is Open

90˚ (Max.Signal)

When Valve is Open

0˚ (Min. Signal)

When Valve is Open

Actuator

Supply Hoses

(Note 4)

Normal

Reverse

Normal

Reverse

Normal

Valve

Position at

Min. Signal

Closed

Open

Closed

Open

Closed

Open

Closed

Open

7) Align the mounting holes and then use the two

-18 socket

head cap screws, lockwashers, hex nuts, and rubber washers
(between bracket and positioner) supplied with the mounting
kit to fasten the positioner to the bracket.

8) Tighten the set screw at the upper end of the coupling to the

positioner shaft (seat the set screw in the positioner shaft
groove). The other two set screws will be tightened after the
actuator is cycled 90˚. Proper alignment of the positioner spindle
to the actuator shaft is very important since improper alignment
can cause excessive wear and friction to the positioner.

C. CONNECTIONS

Air connections are tapped for

" NPT male connectors and are

clearly marked. We recommend use of tape, Loctite

577 or

similar user preferred for sealing.

Port I Input instrument pneumatic signal 20–100 kPa (3–15 psi)

Port S Supply air, maximum 0.9 MPa (125 psi)

Port C1, C2 Actuator connections (0.2–0.9 MPa). C2 opening port.

Connect the air supply line to port S.

For double-acting operation, connect the right-hand and left-hand
ports of the actuator end cap (right-hand end cap when facing
actuator nameplate) to port C2 and C1 respectively.

For single-acting operation, plug port C1 for increasing signal to
open or close. Plug port C2 for decreasing (reverse) signal to
close.

3. OPERATION

The PM15 operates on a force balance principal. Force is originated
by the signal pressure transmitted through a diaphragm onto the
balance arm. The opposing force is achieved through the feedback
spring and is proportional to the position of the lower arm. The lower
arm position is determined by the position of the cam which is
secured to the spindle and connected to the actuator shaft thus
providing the feedback from the actuator/valve. When these two
forces are equal, the balance arm and the spool in the pilot valve is in
a neutral position — the complete unit is in a balanced position. Air is
supplied to the pilot valve through port S, and controls the air flow
through ports C1 and C2.

Assume an equilibrium position.

An increased control pressure will deflect the diaphragm (1) down,
compressing the feedback spring (3). The balance arm (2) moves the
spool (7) in the pilot valve (8) furnishing supply air to the actuator,
while at the same time air is exhausted from actuator and is vented to
atmosphere through the pilot valve.

With the increased supply air, the actuator rotates (or moves linearly)
moving the positioner spindle (6). The spindle and cam (5) rotate,
forcing the lower arm (4) upwards compressing the feedback spring
(3). This motion will continue until two forces are equal and the unit
is an equilibrium position.