Powers 593 User Manual

• Up to 1380 lbs. of
force

• Excellent range
control

• Accurate repetitive
positioning

• Dual NAMUR
Accessory Mounts

• Field Reversible

• “Long-life” design
lasts over one
million cycles

46” Actuator

Powers’ most popular actuator is

powerful, durable, and versatile.

TABLE OF CONTENTS

Features . . . . . . . . . . . . . . . . . . . . . . . .2

Description . . . . . . . . . . . . . . . . . . . . .3

Guide to Applications . . . . . . . . . . . . .3

Operation . . . . . . . . . . . . . . . . . . . . . .3

Installing an Actuator . . . . . . . . . . . . .4

Changing Springs . . . . . . . . . . . . . .4-5

Changing Action . . . . . . . . . . . . . . .6-7

Preload . . . . . . . . . . . . . . . . . . . . . . . .8

Replacing a Diaphragm . . . . . . . . .9-10

Parts List . . . . . . . . . . . . . . . . . . .11-13

Spring Range Matrix . . . . . . . . . . . . .13

Modification Data Table . . . . . . .14-16

TI-593-672

2

1. Optional stainless steel springs
extend operating life to over
one million cycles.

2. Nested spring design creates a
uniform stroke by eliminating
spring side flex.

3. 316 Stainless steel thrust
plate is corrosion resistant.

4. All stainless steel hardware
used in combination with SS
spring makes long-life
standard.

5. Molded fiber and reinforced
diaphragm greatly reduces the
risk of stress cracks.

6. Rolling diaphragm design
allows for even pressure
during the stroke cycle
making for more precise
control.

7. Field reversible design makes
changing the fail-safe mode
possible.

8. With *extended nut hardware,
preload can be safely released
for inspection.

9. Dual NAMUR mounts can be
used to quickly add or
reorient accessories.

FEATURES

*

5

3

6

2

1

8

9

DESCRIPTION

Powers’ most popular actuator, the ‘46’, is a versatile, field reversible
design that is available on most Flowrite II valves. This actuator
provides:

• large effective area (1380 lbs of force at 30 psi) for powerful
valve close control

• excellent narrow range control signal performance

• accurate repetitive positioning due to large diameter
diaphragm, low friction actuator stem and bronze bearings, and

• dual NAMUR accessory mounts.

The 46 actuator and Flowrite II valves are designed to integrate intro a
highly flexible system. It is possible through the Flowrite II 46”
actuation system to adapt to changing application requirements by
reconfiguring the actuator through simple spring changes, stem
changes, etc. The purpose of these instructions is to suggest solutions
to meet your applications needs.

OPERATION

The actuator springs provide the necessary force to hold the stem in
the lowered or raised position.
On a Normally Open valve (ATC, D/A) assembly, the stem will
start its downward stroke whenever the control air pressure applied
against the actuator diaphragm area and upper housing exceeds the
holding force of the springs.
A further increase in control air pressure will initiate a continued
downward travel of the valve stem until the valve has completed its
stroke.

On a Normally Closed valve (ATO) assembly, the valve stem will
start its upward stroke whenever the control air pressure applied
against the actuator diaphragm area and the lower housing exceeds
the holding force of the springs.
A further increase in control air pressure will initiate a continued
upward travel of the valve stem until the valve has completed its
stroke.
The air pressure change to initiate full stem travel is known as the
throttling range or spring span. Standard spring span is equal to 8
psi (55 kPa) with no drop across the valve.
This throttling range is based on typical system pressure and will
vary slightly as the pressure drop across the valve changes. A
decrease in pressure at the diaphragm will initiate an upward
movement on a normally open valve assembly and a downward
movement on a normally closed valve assembly.
When the valve is at its wide open position, the disc and throttling
plug are farthest from the seat and there is maximum flow through
the valve.
Valve actuators equipped with a pilot positioner can utilize full
control air pressure at any point in the stem travel to initiate stem
movement or to maintain stem position.
However, the actuator springs still provide the necessary force to
move the stem in the opposite direction.
Use of a positioner will tend to provide faster response and to ensure
repeatability of stem position regardless of the load on the actuator.
However, in a system where available pressure and flow
requirements are relatively consistent, control valves can usually
perform adequately without a positioner.

GUIDE TO APPLICATIONS

To reverse actuator action, i.e., change an NO to an NC valve,
or an NC to an NO valve:

1. Refer to the Modification Tables for correct replacement parts.

2. Follow instructions for Reversing Actuator Action.

3. Follow instructions for Preload Adjustment.

To attempt valve sequencing with a 3-15 psi air signal OR to set
a NC valve assembly at a higher preload to maintain closeoff or
to increase the throttling range:

1. Refer to the Modification Tables for correct replacement parts.

2. Refer to Changing Springs.

3. Follow instructions for Preload Adjustment.

4. Use dimensions in the Spring Range Matrix.

To modify the actuator action, i.e., using the same actuator on a
different valve body or size:

1. Refer to Modification Tables for correct replacement parts.

2. Refer to Changing Springs.

3. Refer to Changing Action (changing stems).

4. Follow instructions for Preload Adjustment.

5. Use dimensions in the Spring Range Matrix.

To install an actuator on a valve and set the preload adjustment:

1. Follow Installing Actuator instructions.

2. Refer to Modification Tables for correct replacement parts.

3. Follow instructions in Preload Adjustment.

To replace a ruptured diaphragm:

1. Refer to Replacing the Diaphragm instructions.

3

4

CHANGING SPRINGS (DIRECT ACTING ACTUATORS)

Springs can be changed or added if a higher shutoff rating is
required. This may become necessary under the following
conditions:

1. If the pressure of the medium passing through the valve increases,

2. If the valve size increases due to an increase in process demand, or

3. If valve body type is changed.
The Modification Data Tables (page 13-15) provide dimensional
data including part numbers, and number of springs required to
reconfigure an actuator.
Springs may be changed with the actuator assembled or removed
from the valve. For ease of instruction, pictures are shown with
actuators removed.

To change or add springs on a Direct Acting (DA, NO, ATC)
actuator assembled to the valve, follow steps 1, 2, 3, 4A, 5-10.

To change or add springs on a Direct Acting (DA, NO, ATC)
actuator removed to the bench, follow steps: 1-4A, 5-9.

To change or add springs on a Direct Acting (DA, NO, ATC)
actuator assembled to the valve and under preload, follow steps:
1, 3, 4B, 5-10.

1. Shut off controlled medium supply (steam, water, or other
liquid).

2. Reduce preload on the springs (refer to Decreasing Preload

on DA Actuators pg. 7).

3. Remove the control signal to the actuator.

4A. (Fig. 1) Remove top housing nuts and bolts or (see above)
4B. (Fig. 1) Remove the three bolts attached to the short nuts,

then equally release the bolts attached to the long nuts.

CAUTION: Springs under tension.

5. (Fig. 2A) Remove upper housing.

6. Remove stem nut, silver and black washers (Fig. 2B).

7. Remove diaphragm, and thrust plate (Fig. 2C).

8. Change or add springs as needed (Fig. 3A & 3B). Make sure

the springs are properly placed over the spring guides
and their configuration is symmetrical.

9. Reassemble parts in reverse order, then attach upper housing.

10. Adjust preload ref.

NOTE: Some actuator models have small springs nested inside
the larger springs. The small springs also fit over spring guides
and must also be placed symmetrically.

Fig 1 - Remove Housing Bolts
*(extended versions last and gradually)

Fig 2A - Remove Upper Housing

Fig 2B - Remove Stem Nut, & Washers

INSTALLING AN ACTUATOR

1. Place actuator assembly over valve stem. With actuator stem and
valve stem separated, place bonnet lock nut over valve stem onto
bonnet.

2. Apply air pressure to the actuator approximately 9 psi for a
Normally Closed valve assembly, and 3 psi for a Normally Open
Assembly.

3. Tighten the valve stem to the actuator stem by rotating the valve
stem (NOT THE ACTUATOR STEM).

4. Tighten the two locknuts together and rotate them clockwise.
Tighten the nuts to achieve the proper PRELOAD (as explained in
the Preload Section).

5. Remove air pressure.

6. Tighten the bonnet locknut on the bonnet (Fig.1).

Fig 1 - Tighten the Bonnet
Lock Nut on the Bonnet

CHANGING SPRINGS (REVERSE ACTING ACTUATORS)

Springs may be changed with the actuator assembled or removed
from the valve. For ease of instruction, pictures are shown with
actuators removed.

To change or add springs on a Reverse Acting (RA, NC, ATO)
actuator assembled to the valve, follow steps 1-4A, 5-8.

To change or add springs on a Reverse Acting (RA, NC, ATO)
actuator removed to the bench, follow steps: 1-4A, 5-7.

To change or add springs on a Reverse Acting (RA, NC, ATO)
actuator assembled to the valve and under preload, follow steps:
1, 3, 4B, 5-8.

1. Shut off controlled medium supply (steam, water, or
other liquid).

2. Reduce preload on the springs (refer to Decreasing Preload
on DA Actuators pg. 7).

3. Remove the control signal to the actuator.

4A. (Fig. 1) Remove top housing nuts and bolts or (see above).
4B. (Fig. 1) Remove the three bolts attached to the short nuts,

then equally release the bolts attached to the long nuts.

CAUTION: Springs under tension.

5. (Fig. 2A) Remove upper housing.

6. Add or remove springs as needed for new configuration

(Fig 3A &Fig. 3B). Make sure the springs are properly placed
over the spring guides and their configuration is symmetrical.

NOTE: Some actuator models have small springs nested
inside the larger springs. The small springs also fit over
spring guides and must also be placed symmetrically.

7. Reassemble upper housing.

NOTE: Assemble bolts with long nuts first.

8. Adjust preload ref pg. 7.

Fig 1 - Remove Housing Bolts

Fig 2- Remove Upper Housing

Fig 3A - Typical 3-Spring Installation
NOTE: *Number required may vary. Refer
to page 14-15.

Fig 3A - Typical 4-Spring Installation

Fig 2C - Remove Diaphragm,
Thrust Plate

Fig 3A - Typical-Spring Installation

5

Springs

Springs

Springs