Greenheck HPR Series User manual

Instructions
The following instructions should be followed when attempting to modify HPR series pressure relief dampers for
different damper orientations or
start-to-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 (see Figure 1). The pressure set is
in the direction opposite the blades and offset, or balance, the weight of
the blades. The counterbalance 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 (see Figure 2) and vertical down flow
(see Figure 3) 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 different crankarms any be used, depending on the damper size and magnitude of start open pressure. (see
Figure 4).
The blades of this type of 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.
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 the 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 the damper flow direction must be changed in the field, loosen fastener in pressure set crankarm and rotate arms
to correct position. See Figures 1, 2, and 3 for correct pressure set arm orientation with damper blades closed.
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 the arms. In extreme cases, the arm length and quantity must be
changed. See table at the end of the 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 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 the arms. In extreme cases, the arm
length and quantity must be changed. See table at the end of the 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.
FLOW
DAMPER BLADE
COUNTERBALANCE
PRESSURE SET
Figure 1 Horizontal Flow
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HPR Series 1
Document 469134
HPR Series
Instructions For Adjusting Pressure Relief Dampers
Installation, Operation and Maintenance Manual
Please read and save these instructions for future reference. Read carefully before attempting to assemble, install,
operate or maintain the product described. Protect yourself and others by observing all safety information. Failure
to comply with these instructions will result in voiding of the product warranty and may result in personal injury
and/or property damage.

Figure 4: Crankarms
2
13
Small crankarm
8 1/2 in. (216mm)
Medium crankarm
12 1/2 in. (318mm)
Large crankarm
Applicable Model Components Galvanized Part
Number
Stainless Steel
Part Number
HPR-120 Axle adapter, 3⁄8in. sq. to ¾ in. OD, 3 in. long 458959 NA
HPR-120 Axle adapter, short, ¾ in. OD 370120 416343
All ¾ in. crankarm 653630 687738
All 3⁄8in.-16 x 2 crankarm bolt 415882 415924
All 3⁄8in.-16 hex nut for crankarm 415457 416168
All Short counterweight arm (8½ in.) 647344 689404
All Long counterweight arm (12½ in.) 657343 683951
All 3⁄8in.-16 set screw for short/long arm 415050 415763
All 3⁄8in.-16 weld nut for short/long arm 415127 415928
All Counterweight plate, 1¼ in. x 3½ in. 653144 687637
All Counterweight plate, 2½ in. x 3½ in. 653143 687636
All Counterweight plate, 3½ in. x 3½ in. 653142 687635
All Bolt, ¼ in. - 20 x 1¼ in. 415973 NA
All Bolt, ¼ in. - 20 x 1½ in. 415517 416103
All Nut, ¼ in. - 20 415455 415575
Table of Components
FLOW
DAMPER BLADE
Figure 3 Vertical Down Flow
FLOW
DAMPER BLADE
Figure 2 Vertical Up Flow
469134 • HPR Series, Rev. 7, September 2023 Copyright © 2023 Greenheck Fan Corporation2
As a result of our commitment to continuous improvement, Greenheck reserves the right to change specifications
without notice.
Product warranties can be found online at Greenheck.com, either on the specific product page or in the
literature section of the website at Greenheck.com/Resources/Library/Literature.
®
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