Massachusetts is enforcing the fire codes. We are finding that many ducts are not welded properly. Many welds and seams leak. We need to have some kind of test or procedures to determine if the duct is liquid tight. Lights is one way but often restricted to ducts that are in open space where one can see the light coming out of the voids. Anyone have any suggestions?
Test for liquid tight duct
- Thread starter Przrat
- Start date
Christopher
Moderator
You can do pressure testing like what they do for pipes.
They put a flange on both ends and pressure it with water and see what the pressure is for a while, not sure if it is an hour or hours.
I think you could have some type of air bag that you could put in both ends of the duct, inflate and see if it holds air pressure for a while and if not you could put smoke into the duct and then pressure it again and walk the duct to see where the leaks are.
This should be done before it is installed in new construction and be part of the job scope so it is done for all new construction.
Besides being in the new fire code, it should be in new construction code, ordinances, etc.... so that the word gets out so that it gets done hopefully.
They put a flange on both ends and pressure it with water and see what the pressure is for a while, not sure if it is an hour or hours.
I think you could have some type of air bag that you could put in both ends of the duct, inflate and see if it holds air pressure for a while and if not you could put smoke into the duct and then pressure it again and walk the duct to see where the leaks are.
This should be done before it is installed in new construction and be part of the job scope so it is done for all new construction.
Besides being in the new fire code, it should be in new construction code, ordinances, etc.... so that the word gets out so that it gets done hopefully.
That is actually a very difficult question to answer. I can think of many different ways to accomplish this but there are faults with each.
- Air pressure test; the issue here is that it is possible for the duct to be liquid tight but not airtight especially under pressure (also duct work not required to be checked under pressure, could run into problems with older duct work coming apart during test either from rot, etc).
- Water pressure test; first the duct work would have to be 100% clean otherwise the grease could act as a seal and wouldn't show minor leaks. could also run into same issue as above regarding pressurizing old ducts.
- Smoke test; would show major leaks but may not have enough volume/pressure to identify smaller leaks.
Of coarse, any of these methods would identify major deficiencies, but it really depends on how close to exact liquid tight you're looking for. I would say the best bet would be to do the check when the cleaning is being performed. The duct spinner should be sufficient enough with pressure and volume to be able to identify where any gaps in the system are. I've seen where sprinkler systems have failed water pressure tests with no visible water loss from the system. Hope this helps somehow. I don't know exactly how stringent they are enforcing up there.
Are all of the restaurants up there meeting code with duct type and wall thickness?
- Air pressure test; the issue here is that it is possible for the duct to be liquid tight but not airtight especially under pressure (also duct work not required to be checked under pressure, could run into problems with older duct work coming apart during test either from rot, etc).
- Water pressure test; first the duct work would have to be 100% clean otherwise the grease could act as a seal and wouldn't show minor leaks. could also run into same issue as above regarding pressurizing old ducts.
- Smoke test; would show major leaks but may not have enough volume/pressure to identify smaller leaks.
Of coarse, any of these methods would identify major deficiencies, but it really depends on how close to exact liquid tight you're looking for. I would say the best bet would be to do the check when the cleaning is being performed. The duct spinner should be sufficient enough with pressure and volume to be able to identify where any gaps in the system are. I've seen where sprinkler systems have failed water pressure tests with no visible water loss from the system. Hope this helps somehow. I don't know exactly how stringent they are enforcing up there.
Are all of the restaurants up there meeting code with duct type and wall thickness?