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Duct Leakage Testing - SUPPLY SYSTEM

To perform a proper duct leakage test using an ORIFLOW duct leakage tester, perform the followingsteps:

1. Use the orifice plate with the recommended leakage range for your job. Use our online

program to help determine which plate(s) you can use with our testers.

2. Make sure you have adequate electrical power for the fan. DO NOT OVERLOAD extension

cords. Make sure you use one with the proper gauge.

3. Cover all outlets with plastic bags and seal with duct tape.

4. Allow all joints and seams that were sealed with duct sealer to cure for at least 24 hours or the

required cure time by the manufacturer, whichever is greater.

5. If possible, position the ORIFLOW duct leakage tester in a location where there will be a

straight path from the orifice tube outlet to the location where you will feed air into the system.

6. Drill a 3/8" diameter hole no closer than two or three feet away from the flexible duct to system

 joint.

7. Place the pressure tubing into the previously drilled hole; extend 6 to 12 inches into the duct.

8. Seal the tubing penetration joint with putty or tape.

9. Zero both gauges. Locate adjusting screw on center front of gauge. Use a small slotted

screwdriver. Turning clockwise increases the pressure reading, counter-clockwise decreasesit.

10. Close the fan's inlet damper so the duct system does not get overpressurized by the tester.

11. Turn on the tester blower.

12.Adjust inlet damper until the reading on the gauge marked "Duct System" is at the system

pressure required for performing the leakage test.

13.Once the duct system pressure has been reached and stabilized, note the reading on the

gauge marked "Orifice Tube". This pressure drop reading will correspond to the amount of air you're feeding into the duct system, which is the amount of air that is leaking out.

14.Refer to the calibration table that came with your test rig. Find the pressure reading and note

the corresponding leakage rate.

Troubleshooting:

If the "Orifice Tube" gauge exceeds the maximum range, the system is probably leaking too much air.Investigate system for missed outlets or unsealed joints. You can also use a larger orifice or a gaugewith a larger range.

If you cannot obtain any pressure (or very little pressure) with the blower on and the inlet damper wideopen, it could be due to one of the following problems:

1. Using too small of an orifice plateIf pressure drop across orifice plate is more than 2 in.wg., use the next greater sizedorifice plate. Use our online program to determine which orifice plate you should usebased on the maximum allowable leakage. You can also refer to graphs for eachtester/plate combination.

2. System has more leakage at test pressure than is allowedWhen using the C1, C1D or C2 tester, use the 4-inch plate to pressurize your systemand refer to the following table to determine if your system is leaking more than themaximum capacity of the tester.

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Also check your flex-duct connections Wrap duct tape tightly around the joint and feelfor leaks. Rectangular duct joint corners can be typical leaky points. If fire damper 

and/or heater coils are part of the system you are testing, they also can be significantleak contributors. A smoke machine may be used to help locate leaks; contact us for more information.

3. Equipment not working properlyMake sure the equipment is working properly by doing the following steps:

• turn off blower.

• observe blower wheel rotation direction when it slows down (view from lookingthrough inlet safety screen); it should be rotating clockwise (if not, contact us).

• completely close inlet damper.

• disconnect the flex-duct from the tester.

• turn on blower.

• Slowly open inlet damper and verify that you can feel air coming out of the orificetube.

• the orifice tube gauge pressure drop reading should be maxed out.

• you can verify gauges are working properly by removing pressure tubing andcarefully apply pressure by gently blowing into tube end as if trying to inflate aballoon.

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System StaticPressure(in.wg.)

Max Leakagewith C1/C1D

Tester (cfm)

Max Leakagewith C2 Tester 

(cfm)

1 655 550

2 645 540

3 630 510

4 600 455

5 545 365

6 465 230

8 200 --

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Welcome AABC, NEBB, SMACNA and TABB members

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