Product Overview

ManualsBrandsBarber Colman ManualsDampers4" Post Mount Damper Actuator w/ Positioner (8-13 PSI)

POSITIVE POSITIONER ADJUSTMENT

See Figure-1.

Span

The signal pressure change required to produce full actuator

stroke is determined by the feedback spring. Cataloged

models are supplied with factory installed 5 psi springs.

M556-14 is also supplied with a 10 psi spring attached to the

feedback arm.

Start Point

The signal pressure at which the actuator shaft begins to

move is adjustable 3 to 12 psig by rotating the recessed brass

knurled dial in the center of positioner.

The start point of the actuator may be adjusted by setting the

signal pressure to the desired value and turning the recessed

knurled wheel by hand until the actuator shaft begins to move.

Turning the wheel outward (toward the spring) raises the start

point.

the positioner requires a signal connection to “S” and a main

air connection to “M”. The positioner output, located above the

needle valve, is connected to the actuator signal port.

Adjustable Needle-Valve

Needle-valve allows the adjustment of the rate of actuator

movement.

With this needle-valve, 3", 4" and 6" actuators may be

adjusted with a small blade screw driver, if required, to:

Give the actuators the same relative rate of movement.

This makes it possible, for example, to have outside, return

and relief damper on an air handling unit move “together”,

rather that at different rates. This is especially important -

• When large air handling units are started and

stopped.

• When the dampers are switched from “summer” to

“winter” operation (or vice versa).

Both of the above examples can cause large damper

movements.

A narrower controller throttling range frequently can be

used if the actuators are adjusted to move slowly.

This is important for -

• Controlling supply air static pressure with a vortex

damper.

• Controlling mixed air temperature with outside, return

and relief dampers.

• Controlling space static pressure with one or more

relief dampers.

MOUNTING INSTRUCTIONS

M556

External Mounting

See Figure-2.

Whenever feasible, an M556 piston actuator operating an air

control damper should be mounted external to a duct by

means of its standard swivel post and plate. If necessary, the

mounting surface should be reinforced to withstand the stroke

force of more than 700 pounds that the M556 can exert.

When ordered properly, a control damper will have one or

more shaft extensions for the required number of actuators.

These extensions will be in their retracted or “stored” positions

when shipped and must be extended and locked in position

with their set screws or through bolts.

Before the actuator is mounted, the effective length of its

threaded crank arm should be adjusted to provide the

required damper rotation for full stroke (See table in Figure-2).

In addition, the “normal” position of the damper blades (open

or closed when signal air is removed and the actuator piston

retracts) and direction of shaft rotation as the piston is

extended must be determined to establish the orientation of

the actuator. If this orientation causes the positioner (when

furnished) to be located on the same side of the actuator as

the crank arm, there may be interference between the crank

arm and the feedback arm during operation. In this event, the

relationship between the mounting plate and the positioner

should be reversed by temporarily disconnecting the factory

tubing connection, swinging the mounting post 180° with

respect to the actuator housing and then re-connecting the

tubing.

After the above steps have been completed, the crank arm

clevis can be slipped onto the damper shaft extension without

clamping and the position of the mounting plate can be

determined by forming a right triangle (See Figure-2), with the

hypotenuse being the “effective length” of the threaded crank

arm and the base (along the centerline of the actuator) being

one-half of the actuator stroke (3", 76 mm). The mounting

plate can then be attached to the duct with suitable fasteners,

using care not to obstruct the movement of the damper

blades.

Note:

Note that the actuator need not be mounted at a right

angle to the damper frame.

The final installation step of locking the crank arm to the

damper shaft extension should be done when control ar is

available or by means of a squeeze bulb:

a. For a normally closed damper, apply air pressure to

the actuator equal to the low end of its spring range,

e.g.: 8 psig (55 kPa) for an 8 to 13 psig (55 to 90 kPa)

spring, then close the damper blades against their

stops; a slot in the end of the extension shaft

indicates blade position. After assuring that it is

parallel to the duct surface, clamp the crank arm to

the extension shaft by tightening the outermost crank

arm nut. When air pressure is removed from the

actuator, its residual low end spring force will provide

additional damper close-off pressure.