1) Three types of stainless steel blade seals were tested on dampers - a fabricated seal and two purchased seals. 2) Testing involved measuring air leakage of dampers at varying static pressures and torque levels in both flow directions. 3) The fabricated seal performed well but was not feasible for production. The purchased seals performed better than standard seals and were easy to install, though some noise occurred.

1. Stainless Steel Blade Seal Leakage Testing
DOCUMENT NO. 2016-026
Greenheck Fan Corporation
Facility 5 Laboratory
525 Western Road
Schofield, WI 54476-0410
June 6th, 2016
By: Mitchell Beattie

2. OBJECTIVE
There is currently no standard option for stainless steel blade seals on any damper models. Potential
seal profiles must be leakage tested for data collection and to verify functionality.
TEST EQUIPMENT
36” x 36” HCD frames with HD SS jamb seals were utilized for every test. Both 3V and fabricated
airfoil blades were tested separately. All leakage testing was performed on the HPLC.
TEST PROCEDURE
Fabricated SS Seal
1. The damper was assembled and adjusted to simulate standard assembly. With the
insertion of the fabricated stainless steel blade seal on airfoil blades (see figure 1).
2. 5, 10 and 15 in.lb/Sq. Ft. were applied to the drive axle and data and observations were
noted.
3. The damper was rotated and tested with each torque again in the opposite flow direction.
Purchased blade seal on 3V blades
1. The damper was assembled and adjusted to simulate standard assembly.
2. The purchased stainless steel blade seals were cut to the length of the blade using wire
snips and attached to the end of the blade. Caulk was put on the connection of the blade
seal and blade to try and prevent a loud noise (Figure 2 and 3)
3. 5, 10 and 15 in.lb/Sq. Ft. were applied to the drive axle and data and observations were
noted.
4. The damper was rotated and tested with each torque again in the opposite flow direction.
Purchased blade seal on Fabricated Airfoil blades
1. The damper was assembled and adjusted to simulate standard assembly.
2. The purchased stainless steel blade seals were cut to the length of the blade using wire
snips and attached to the end of the blade (see figure 2).
3. 5, 10 and 15 in.lb/Sq. Ft. were applied to the drive axle and data and observations were
noted.
4. The damper was rotated and tested with each torque again in the opposite flow direction.
Figure 1: Detail view of the fabricated
stainless steel blade seal

3. RESULTS
0.1
1
10
1 10 100
STATICPRESSURE(in.wg)
LEAKAGE (cfm/ft^2)
Fabricated Blade Seal (Front to Back)
standard (at 5 in.lb/ft^2)
no seal (at 5 in.lb/ft^2)
FTB 5 (in.lb/Sq. Ft.)
FTB 10 (in.lb/Sq. Ft.)
FTB 15 (in.lb/Sq. Ft.)
Figure 2: Newly purchased blade seal
attached to the airfoil blade.
Figure 3: Caulk was applied to the connection of
the seal and blade on the 3V blades.
Figure 4: Results of the fabricated blade seal, front to back direction.

4. 0.1
1
10
1 10 100
STATICPRESSURE(in.wg)
LEAKAGE (cfm/ft^2)
Fabricated Blade Seal (Back to Front)
standard (at 5 in.lb/ft^2)
no seal (at 5 in.lb/ft^2)
BTF 5 (in.lb/Sq. Ft.)
BTF 10 (in.lb/Sq. Ft.)
0.1
1
10
1.00 10.00 100.00
StaticPressure(in.wg)
Air Leakage in CFM/Sq. Ft.
Purchased Blade Seal on 3V Blades (Front to Back)
Front to Back 5 (in.lb/Sq. Ft.)
Front to Back 10 (in.lb/Sq. Ft.)
Front to Back 15 (in.lb/Sq. Ft.)
Standard With Seals
Standard Withount Seals
Comment: Blade seals were caulked on contact
to blade to try and prevent noise. Noise was
present around 2 in.lb of static pressure.
Figure 5: Results of the fabricated blade seal, back to front direction.
Note: Results at 15 in.lb/Sq. Ft. were not able to be retrieved.
Figure 6: Results of the purchased blade
seal on the 3V blades, front to back
direction.

5. 0.1
1
10
1 10 100
StaticPressure(in.wg)
Air Leakage (CFM/Sq. Ft.)
Purchased Blade Seal on 3V Blades (Back to Front)
Back to Front 5 (in.lb/Sq. Ft.)
Back to Front 10 (in.lb/Sq. Ft.)
Back to Front 15 (in.lb/Sq. Ft.)
Standard With Seals
Standard Withount Seals
Front to Back
Velocity at 1 in.wg of Static
Pressure (CFM/Sq. Ft.)
5 in.lb 16.80
10 in.lb 14.40
15 in.lb 12.55
Standard With Seals 18.00
Standard Without Seals 35.00
Back to Front
Velocity at 1 in.wg of Static
Pressure (CFM/Sq. Ft.)
5 in.lb 16.41
10 in.lb 15.14
15 in.lb 13.19
Standard With Seals 18.00
Standard Without Seals 35.00
Comment: Blade seals were caulked on
contact to blade to try and prevent noise.
Noise was not heard in this test direction.
Figure 7: Results of the purchased blade
seal on the 3V blades, back to front
direction.
Figure 8: Results at 1 in.wg of Static
Pressure of the purchased blade seal on
the 3V blades., front to back direction.
Figure 9: Results at 1 in.wg of Static
Pressure of the purchased blade seal on
the 3V blades., back to front direction.

6. 1
10
1 10 100
StaticPressure(in.wg)
Air Leakage (CFM/Sq. Ft.)
Purchased Blade Seal on AirfoilBlade (Back to
Front)
standard (at 5 in.lb/ft^2)
no seal (at 5 in.lb/ft^2)
BTF 15 (in.lb/Sq. Ft.)
BTF 10 (in.lb/Sq. Ft.)
BTF 5 (in.lb/Sq. Ft.)
Comment: A loud noise was heard when static
pressure was around 1 in.wg or more.
Comment: No noise was heard during the Back to Front
tests.
1.00
10.00
100.00
1.00 10.00 100.00
StaticPressure(in.wg)
Air Leakage (CFM/Sq. Ft.)
Purchased Blade Seal on AirfoilBlade (Front to
Back)
FTB 15 (in.lb/Sq. Ft.)
FTB 10 (in.lb/Sq. Ft.)
FTB 5 (in.lb/Sq. Ft.)
standard (at 5 in.lb/ft^2)
no seal (at 5 in.lb/ft^2)
Figure 10: Results of the purchased blade
seal on the airfoil blade, front to back
direction.
Figure 11: Results of the purchased blade
seal on the airfoil blade, back to front
direction.

7. CONCLUSION
The fabricated stainless steel blade seal performed well (see figures 4 and 5). Although it had
good performance, it is unsuccessful overall due to manufacturing problems. A die manufacturer
made samples but stated it was not repeatable enough and did not quote the project. The seal was
made in house but brought up issues in production due to the forming process causing extreme
caution.
The HCD-220 (3V blades) with the stainless steel blade seal performed better than the
standard EPDM blade seals (see figures 6-9). Noise was present during the test. Caulk was used to
help prevent this but was still heard on the front to back direction. Furthermore, these blade seals are
very easy to attach.
The HCD-230 (airfoil blades) with the purchased stainless steel blade seal performed very well,
but not as efficient as the standard EPDM blade seals (see figures 10 and 11). The back to front
direction performed better that front to back at lower static pressures. As the static pressure
increased, the front to back performed better (see figures 12-14). This seems to be a strong
performance option along with being a quick process for assembling the blade seals. Further testing
can include further ingenuity into preventing loud ringing from the stainless steel seals.
1.00
10.00
100.00
1.00 10.00 100.00
StaticPressure(in.wg)
Air Leakage (CFM/Sq. Ft.)
Purchased Blade seal on AirfoilBlade Direction
Comparison
FTB 15 (in.lb/Sq. Ft.)
FTB 10 (in.lb/Sq. Ft.)
FTB 5 (in.lb/Sq. Ft.)
standard (at 5 in.lb/ft^2)
no seal (at 5 in.lb/ft^2)
BTF 15 (in.lb/Sq. Ft.)
BTF 10 (in.lb/Sq. Ft.)
BTF 5 (in.lb/Sq. Ft.)
Front to Back
Velocity at 1 in.wg of Static
Pressure (CFM/Sq. Ft.)
5 in.lb 8.83
10 in.lb 6.26
15 in.lb 4.83
Standard With Seals 3.00
Standard Without Seals 35.00
Back to Front
Velocity at 1 in.wg of Static
Pressure (CFM/Sq. Ft.)
5 in.lb 6.17
10 in.lb 5.30
15 in.lb 4.07
Standard With Seals 3.00
Standard Without Seals 35.00
Figure 12: Results of the purchased blade
seal on the airfoil blade both directions.
Figure 13: Results at 1 in.wg of Static
Pressure of the purchased blade seal on the
airfoil blades, front to back direction.
Figure 14: Results at 1 in.wg of Static
Pressure of the purchased blade seal on the
airfoil blades, back to front direction.