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Controller for compressor on a leaky air system?

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  • Controller for compressor on a leaky air system?

    The air distribution system in the 50-plus-year-old building at the school has a leak that we cannot find. If no air is being used, the 10-HP compressor with a 120-gallon tank cycles about every thirty-five minutes. The building has been modified extensively over the years, and there are unused lines and outlet fittings buried behind new walls. No one wants to tear up the building looking for the leak.

    Is there a way to build a controller that will measure the time between compressor turn-ons, and shut down the system if the it's not being used? I was thinking if the time between turn-ons was thirty-five minutes three time in a row, the system would be shut down because that's just keeping up with the leakage. A shorter time between turn-ons would indicate the system was being used, and it would stay on. That would keep the compressor from running so much overnight and on the weekends. A second function of the controller would turn it back on automatically on weekday mornings so it would be ready to go when classes started.
    Any products mentioned in my posts have been endorsed by their manufacturer.

  • #2
    Do a Google search for 7 day timer. A timer to shut it down during off hours and weekends sounds much simpler.

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    • #3
      Uhm, why not install valves going to different sections of the building, and figure out where the leak doesn't exist?

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      • #4
        Solenoid valve at the tank,timer controlled to be shut off after hours.
        I just need one more tool,just one!

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        • #5
          Originally posted by winchman View Post
          ... there are unused lines and outlet fittings buried behind new walls. No one wants to tear up the building looking for the leak.
          If this were my building, being as lazy as I am, I would think it easier than building a controller and quicker to just cut and cap the unused, buried lines (since they aren't used anyway). If you have to bridge a cut off line, I'd use PEX tubing and a couple fittings. this not only is easier, it actually fixes the problem instead of putting a band-aid on it. Win win.

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          • #6
            Originally posted by tyrone shewlaces View Post
            If this were my building, being as lazy as I am, I would think it easier than building a controller and quicker to just cut and cap the unused, buried lines (since they aren't used anyway). If you have to bridge a cut off line, I'd use PEX tubing and a couple fittings. this not only is easier, it actually fixes the problem instead of putting a band-aid on it. Win win.
            Aye. The controller, even a free one, still wastes air.

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            • #7
              You could also get an ultrasonic leak detector and find the leak that way. They listen at ultrasonic frequencies where the leaks are much easier to find. Spending the time and money to build a controller is silly.

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              • #8
                I am with the camp that favours repairing or bypassing
                leaks. How many outlets in how many locations through
                how many obstacles would it take to address present and
                anticipated needs?

                I got a great deal on my nearly new big compressor
                because a housing authority responsible for building
                maintenance on several properties had come to the
                realization of how expensive air is for operating heating
                control valves in older buildings w/ porous piping.

                A decision to go a different direction led to a wholesale
                change-over with the aim of reducing operating/maintenace
                costs. Subsequently, building needs for air were much
                reduced and smaller compressors were installed. Seemed
                like a dumb solution for them, but I sure am glad they went
                this route.

                .

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                • #9
                  Getting the over-worked maintenance department to do anything that's not an absolute emergency is out of the question and they won't let anybody else touch it, so doing something about the real problem just isn't possible. That's why I was looking for something that actually could be done.

                  The seven-day timer sounds like a good suggestion. Thanks for that.
                  Any products mentioned in my posts have been endorsed by their manufacturer.

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                  • #10
                    On your controller idea, if it shuts it down after a period of non-use, I would assume the leak would bring it down to zero. Then, how would that controller know when to turn it back on. With zero pressure there can not be any use. You say it would turn it on in the morning, but what about after lunch? Or perhaps an evening class? I think you would need additional means of turning it back on. Overall, this does not sound like a practical idea.

                    The timer sounds good. I hope your maintenance department will let you change the programming. Otherwise there will be a problem whenever the schedule changes or someone wants to use it at an odd hour.

                    Anything you do will require some installation. You say your overworked maintenance department can not find time to do any detective work. But eventually the compressor will wear out and that will happen faster if this leak continues. Repair or replacement of the compressor will also require time; probably a lot more than the installation of a valve or two would. I would have a serious sit down with the head of that department and outline the situation. See if he/she would agree to some small measures. If you can install one or two valves at a time to allow you to isolate about half of the system from the compressor/tank and observe the cycle time after hours, then you can find the leak one night at a time. By dividing the system into halves or as close to that as you can, you can get to the leak in the smallest time and effort. One valve will do the first half. Then you know where to add the second valve. Keep going by halves until you have it isolated.

                    If the maintenance manager will not go along with that, perhaps you can get an outside contractor to work with you on it. Or perhaps you can go to the school authorities and get some funds earmarked for this. Again, use the compressor is wearing out prematurely argument.

                    Here's another thought. Natural gas has an odorant added to it to make leaks obvious. You would not want to use that same odor for this, but perhaps you can find another odorant that can be added to the tank so you can find the leak. Just go around the building and see where the scent is the strongest. Perhaps a bottle of inexpensive perfume. Or an air freshener liquid.
                    Paul A.

                    Make it fit.
                    You can't win and there is a penalty for trying!

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                    • #11
                      Originally posted by Paul Alciatore View Post
                      If the maintenance manager will not go along with that, perhaps you can get an outside contractor to work with you on it. Or perhaps you can go to the school authorities and get some funds earmarked for this. Again, use the compressor is wearing out prematurely argument.
                      A compressor that big isn't exactly sipping electricity. The guys who pay that bill might notice a drop after the leak is fixed. Just another argument for fixing the leak.

                      I wonder if there's something similar to HVAC duct sealant that will fix the leaks without clogging up the air outlets.

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                      • #12
                        Originally posted by Paul Alciatore
                        Or perhaps you can go to the school authorities and get some funds earmarked for this.
                        This! Or a varient, there of.

                        Time to get canny.

                        Fifty years old, huh? Is there a formal or informal alumni association?
                        Given the technical nature of the facility and this much history, surely
                        there is one or more benevolent types amongst whom an appeal could
                        resonate. Offer to name corridors after significant contributors or something
                        along these lines ...

                        .

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                        • #13
                          I agree with the above... Argue for lower repair costs and power savings. If this does not get the attention of the higher ups then the idea of odor detection is a good one. A simple approach would be to load the inlet filter with a cheep and very strong smelling purfume or industrial odorant. Do this when the system is at 0 PSI then start it up and go for a smell a few hours later. Once the smell is located simply clean the inlet filter and bleed off the stored air....
                          Robin

                          Happily working on my second million Gave up on the first

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                          • #14
                            The odor idea sounds like a potential winner. But if it comes down to the simple fact that your "over-worked maintenance department" insists on doing all the work including finding the leak with this odor trick then there's always the good old built in controller idea...... just manually shut the darn thing off at the end of the day and then back on first thing in the morning. It worked for literally many decades before arduinos and other such things came along.

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                            • #15
                              PLC type process controllers by AB an Siemens appeared, replacing the ladder type electrical control panels using tons of relays, timers, stepper switches, etc. EBay shows them from 150 bucks and up. Someone will need to have programing experience.

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