Water Testing Ductwork Grease Duct - Leak Testing KES: DuraVent. The one method that truly holds water. Read what works with this Leak Test White Paper (PDF). What You Will Need for Testing: A Welder with welding equipment (MIG welder highly rec- ommended). A Testing company with high pressure washer, hose, spin jet, spray lance with 15 degree or wider nozzle, 2 mil or thicker poly film, wet vacuum with hose, 30 or 40 gallon brute bucket, duct tape and clamps. Proper forms. Testing Procedures: Step 1. Water testing of ductwork is to be done after all ductwork, access plates, and hoods are installed and welded, but before the duct is insulated. Step 2. Verify proper access and that there is no sealant in the weld ductwork (sealing on listed/prefab ductwork must be per listing). Step 3. Set up hood with the poly film to funnel all water into a 30 gallon bucket (brute style). You will need to tape and clamp the plastic to make sure no water gets on floor or walls. Step 4. Set up under any horizontal ductwork in case of leakage. Make sure you can get to all areas of the duct with ladders, etc. Step 5. Have the welder and a spotter set up outside the ductwork to check for any leaks while the duct is getting sprayed out with a spinet or spray lance. Make sure they have plenty of light. Step 6. Have the cleaning company feed their high pres- sure line using a spin jet or Roto-nozzle at the end through all of the ductwork, starting at the hood prefer- ably, and working up toward the fan. You may start any- where. As long as the entire interior of the duct including all joints are sprayed with water and you are working lin- early toward the opposite point. All of the interior of the ductwork in the system is to be sprayed. (On systems with 2 inlets from hood, you will need to feed down each side and also down any horizontal ducts). The spraying should be done at a rate of approximately 1 foot per 5 seconds. Step 7. If there are no leaks or all leaks are repaired, go to step 10. Step 8. Welder is to re-weld all leaks (if needed). Step 9. Retest system starting at step 5. Step 10. Remove all water with a wet vacuum from the ductwork and the hoods, dry hood with rags or vacuum and remove plastic. Leave area as clean or cleaner than found. Step 11. Fill out complete leak testing form (see Kitchen Water Leak Test) with signatures from testing company and job representative.