Dirty talk chat no member
IMHO, the way I look at this question, I always had two goals.Detect abnormal condition early before subsequent castastrophic failure occurred.I agree with previous thread that regular inspection of filters would be helpful.PMs Good luck "There is plenty of room at the top because very few people care to travel beyond the average route.switch how do you calculate the correct differential pressure across the filter to know when hes dirty? Filter types vary but say a perf 2" filter with a max velocity of 500fpm if all was well ie duct size, cfm dilivery.then you could measure pressure drop but like you said with vfd's it's all off the table.So I take a somewhat pragmatic and practical view of these things.For filter monitoring, you have to determine your goal(s).
The pressure across the filter can be influenced by the VFD but the fan should already be set up to perform with design specifications.
Change filters at some convenient and efficient time, neither too early nor too late, so as to not waste materials, or manpower in extra repeat visits to the same equipment.
Detect an abnormal condition early enough to take a preventative action before a catastrophic failure.
Also the other two variables, cfm & duct size are almost never exactly correct.
I guess a person could build a filter box with a set cfm and determine if a filter is plugged but it's a whole lot more easy just to look. Filters should be changed for biological reasons before they are changed for how clogged they are, I never understood why people insist on saving such a small value for something that can cause so much grief.