Greenheck HPR Series Adjustment on Pressure Relief Dampers User Manual

Document number 469134

HPR series

The following instructions should be followed when attempting to modify HPR series pressure relief dampers for different damper orientations or startto-open pressures. Dampers shipped are set for the speciﬁed start open pressure and ﬂow direction.

Pressure relief dampers designed for horizontal ﬂow (vertical mounting) are equipped with two sets of arms (Figure 2A). The ﬁrst set is in the direction opposite the blades and offset, or balance, the weight of the blades. The second set of arms is always positioned horizontally when the damper is closed (approximately vertical with blades open) and hold the blades closed until the start-open pressure is reached. Pressure relief dampers with vertical up ﬂow/relief (Figure 2B) and vertical down ﬂow (Figure 2C) only have one set of arms, as the weight of the edge pivoted blades is either added or subtracted from the weight necessary to hold blades closed.

Damper will respond to a positive differential pressure in the direction of blade opening,

Three (3) different crankarms may be used, depending on damper size and magnitude of start open pressure.

See Figure 1.

The blades of this type damper exhibit a gradual “lift off” as start-open pressure is reached. The operating point is not sharply deﬁned, as when a door suddenly opens. There is a wide ﬂow range where pressure is

approximately constant.

Instructions for Adjustment on

Pressure Relief Dampers

Small crankarm

8 1/2 in. (216mm)

Medium crankarm

12 1/2 in. (318mm)

Large crankarm

Figure 1

COUNTERBALANCE

PRESSURE SET

FLOW

Counterweight Set Procedure (Horizontal ﬂow only)

The counterbalance weights on a vertically mounted damper (horizontal ﬂow), must be adjusted ﬁrst, if the airﬂow direction is changed. This is covered by a separate procedure. Basically, the damper is adjusted for easy operation (blade weight is just counterbalanced) before the pressure set arms and

weights are added.

Pressure Setting Procedure

Position damper in the proper orientation and ﬂow direction.

If a speciﬁc relief pressure is required, install a U-tube manometer or other pressure measuring device in the

duct work to monitor the static pressure.

If damper ﬂow direction must be changed in the ﬁeld, loosen fastener in pressure set crankarm and rotate arms to correct position. See Figures 2A, 2B and 2C for correct pressure set arm orientation with damper blades closed.

DAMPER BLADE

Figure 2A Horizontal Flow

DAMPER BLADE

FLOW

Figure 2B Vertical Up Flow

Pressure Setting Procedure cont....

Start-open pressure is adjusted by either changing weight center distance from axle center line, or by increasing or decreasing the quantity of plates mounted to arms. In extreme cases, the arm length and quantity must be changed. See table at the end of

procedure for replacement parts.

Adjust weight center distance ﬁrst. Loosen fasteners holding weight plates to arm and move inward or outward in arm slot as required. Moving plates toward axle will reduce start-open pressure; increasing the center distance will increase the pressure at which blades start to open. If a greater range of pressure set adjustment is required, add or remove plates from arms as required to obtain the required start-open pressure.

Check all fasteners for tightness.

Table of Components

Components Applicable

Model

Axle adapter, 3/8” sq. to ¾” OD, 3” long

Axle adapter, short, ¾” OD HPR-120 370120 416343

¾” crankarm All 653630 687738

3/8”-16 x 2 crankarm bolt All 415882 415924

3/8”-16 hex nut for crankarm All 415457 416168

Short counterweight arm (8½”) All 647344 689404

Long counterweight arm (12½”) All 657343 683951

3/8”-16 set screw for short/long arm All 415050 415763

3/8”-16 weld nut for short/long arm All 415127 415928

Counterweight plate, 1¼” x 3½” All 653144 687637

Counterweight plate, 2½” x 3½” All 653143 687636

Counterweight plate, 3½” x 3½” All 653142 687635

Bolt, ¼” - 20 x 1¼” All 415973 NA

Bolt, ¼” - 20 x 1½” All 415517 416103

Nut, ¼” - 20 All 415455 415575

HPR-120 458959 NA

DAMPER BLADE

Figure 2C Vertical Down Flow

Galvanized Part Number

FLOW

Stainless Steel Part Number

Our Commitment

As a result of our commitment to continuous improvement, Greenheck reserves the right to change

specications without notice. Specic Greenheck product warranties are located on greenheck.com within the product area tabs and in the Library under Warranties.

Phone: (715) 359-6171 • Fax: (715) 355-2399 • E-mail: gfcinfo@greenheck.com • Website: www.greenheck.com