Greenheck Seal Replacement for Bubble Tight Dampers (HBTR) - Manual (Page 2)

Problem Possible Cause Remedy
Visual see through near axle
Insufficient tightening of perimeter nuts Tighten nuts until seal gap closes
Perimeter nuts too tight causing
excessive squeeze Loosen perimeter nuts so seal relaxes
Small leak at seal perimeter
Roughness or cut across seal perimeter Sand seal perimeter edge smooth. If
near axle, this will require disassembly
of damper. See figure on page 1.
Insufficient tightening of perimeter nuts Tighten nuts until seal gap closes
Dirt on seal or frame Remove dirt
Damper not closing completely
Insufficient actuator torque Replace actuator or increase air
pressure supply if pneumatic
Blade stops not correctly adjusted
(HTBR-451 only) Adjust blade stops
Damper will not open
Insufficient actuator torque Replace actuator or increase air
pressure supply if pneumatic
Higher seal durometer used Replace with correct material
Stuffing boxes too tight Loosen stuffing box clamps to reduce
friction
Leakage around blade fasteners
Seal not caulked outside perimeter
studs
Loosen, caulk and retighten seal
Blowing through seal perimeter
Excessive differential pressure across
blade
Reduce applied pressure
Insufficient seal overlap
Tighten perimeter nuts to squeeze out
seal
Trouble Shooting Guide
Procedure....
G. Lay damper horizontally with the axle on
down side. Insert blade cover with seal. On
larger dampers, it is sometimes easier to
orient damper vertically, open blade and
insert blade cover and seal. Rock blade
cover to engage axle studs. Install several
fasteners to hold blade cover in place.
H. Position damper so blade studs are
accessible and install nuts. If nuts are
stainless steel, apply anti-sieze compound
to studs to prevent galling fastener threads.
I. DO NOT OVERTIGHTEN NUTS ON
PERIMETER STUDS as seal can and will
be squeezed out excessively. Seal should
extend approximately 0.5 inches at axle
perimeter and 0.625-0.75 inches at right
angles to axle. Tighten nuts starting at axle,
alternating side-to-side, and working out to
blade tips.
J. Close damper. Blade tip-to-frame web
distance at top & bottom should be the
same, + 0.5 in. Adjust blade stops as
necessary.
K. Open and close damper blade several times
so blade seal seats and aligns. Wipe off
any excess caulk. Inspect for visual gaps.
If possible, pressurize one side of damper
and use Leak Detect Solution to inspect for
leakage. Adjust per Trouble Shooting Guide.
Copyright © 2012 Greenheck Fan Corporation
Bubble Tight Seal Replacement Rev. 1 Feb 2012