Many people realize that turning off their compressed air at night and on weekends saves energy and operating costs, especially if the system has a significant number of leaks. While you should try to minimize the leaks to less than 10% of your average flow, hitting the stop button when you go home can save quite a bit of money per year.
Often, when implementing this strategy, people complain that they have to wait too long for the system to re-pressurize in the morning when the compressor starts back up. This can be an issue if you have very large storage receiver capacity. Having large capacity helps stabilize your compressed air pressure and help screw compressors run more efficiently, so it is a big benefit.
But there is a solution to the delay, you can put your compressor to sleep using its automatic shut-down feature and simply close the main valve between the large receiver and the plant. By isolating the plant from the compressor room, the compressor air flow will reduce to near zero and the compressor will go to sleep for the night (if it is placed in automatic mode). The compressor will keep the storage receiver filled, supplying the normally very small leakage load in the compressor room, then have lots of air ready to quickly pressurize the system in the morning. If you have desiccant air dryers, you will need to turn these off at night too (or have them set for dew point dependent switching), as the purge will act like a large leak.
A side benefit to this system is cleaner and drier air at start-up. Straight pressurizing the main storage receiver every day can cause excessive oil carry-over and the presence of water as the receiver recharges. This is because high velocities develop in the compressor as it operates at the lower initial pressures during start-up. And the atmospheric air in the receiver and plant piping will not have passed through the air dryer (it leaks in from outside by diffusion). When this air is pressurized some moisture is initially squeezed out.
At least one pneumatic products supplier has air saver valves that will isolate the compressor from the plant but allow remote manual electrical operation of the main system valve (see graphic above) using a selector switch that can be positioned outside the compressor room. Or, it can be programmed to turn the air system on at a certain time of the day — so the air is waiting for you when you arrive in the morning.