Technical Duct Leak Testing Supply System

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

• 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.
• Make sure you have adequate electrical power for the fan. DO NOT OVERLOAD extension cords. Make sure you use one with the proper gauge.
• Cover all outlets with plastic bags and seal with duct tape.
• 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.
• 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.
• Drill a 3/8″ diameter hole no closer than two or three feet away from the flexible duct to systemjoint.
• Place the pressure tubing into the previously drilled hole; extend 6 to 12 inches into the duct.
• Seal the tubing penetration joint with putty or tape.
• Zero both gauges. Locate adjusting screw on center front of gauge. Use a small slotted
  screwdriver. Turning clockwise increases the pressure reading, counter-clockwise decreases it.
• Close the fan’s inlet damper so the duct system does not get overpressurized by the tester.
• Turn on the tester blower.
• Adjust inlet damper until the reading on the gauge marked “Duct System” is at the system pressure required for performing the leakage test.
• 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.
• 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 gauge with a larger range

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

• Using too small of an orifice plate
  If pressure drop across orifice plate is more than 2 in.wg., use the next greater sized
  orifice plate. Use our online program to determine which orifice plate you should use
  based on the maximum allowable leakage. You can also refer to graphs for each
  tester/plate combination.
• System has more leakage at test pressure than is allowed
  When using the Cobra or Lynx tester, use the 4-inch plate to pressurize your system
  and refer to the following table to determine if your system is leaking more than the
  maximum capacity of the tester.

* – Using the largest size orifice plate. Note each tester comes with one plate. Other orifice plate sizes are available for accurate testing of different flow ranges. Use smaller orifices for smaller flow ranges; largest orifice for maximum flow range.