Air System Mulitport Auto Drain
Thought I'd share this method of a reliable compressed air system drain. This may be a bit over the top for a small system, but is perfect for a large system, or a system with lots of scale, condensate and oil from screw compressors.
Almost all automatic electric drain timers sold today, are provided with a 1/4" NPT drain valve. The actual orifice sizes inside these solenoid valves are about 1/8" or less. Making them susceptible to plugging and hence leaking, with small particles of scale.
This example was built for an old plant, from WW2 production. It had many system issues, and many auto drain timers installed on the equipment. The plant was having several problems with contaminated air supply to their robots and dust collector cleaning controls. Oil and particles clogging solenoid valves, and water freezing in their dust collector cleaning controls, during the winter.
Another problem was the plant piping. It had been modified and added to over the years, and there were many sections that trapped water away from the compressed air supply. Some sections were filled with water, like a plumbing trap, and sent liquid slugs of water downstream, when there was demand on the line. No amount of draining at the tank or filters was going to correct this problem.
A compressor contractor had been to the site and installed numerous automatic drains around the supply system, but the problems persisted.
The solution was to build a drain manifold system that incorporated a larger solenoid valve, that could pass larger chunks of scale, oil from large screw compressors, and copious amounts of water from several after coolers, refrigerated dryer, line filters, and plumbing traps in the existing lines. Then drain it all to one oil separator, before dumping of the condensate.
The solenoid valve selected was a 1/2" NPT 120V
Dayton model with a 5/8" orifice, and a
120V coil. Tubing and fittings that were used were 3/8" poly in order to easily pass large particles of scale with ease, some filters would only accept 1/4" tube, so that was used in those instances.
Inline with the solenoid valve, was a 1/2" globe valve, to throttle down the output to a reasonable volume. Two manifold pipes were provided, one for after-coolers and dryers that contained their own internal automatic drains, and one for lines, filters and tanks that needed an automatic drain. The manifold outputs were combined, and then passed onto an oil/ water separator. Oil to a collection container, and water to a local drain. In the photo you can easily see the lines that are pumping oil, with the poly tube.
The timer that was used was a Posi-Drain from
Air System Products, LLC. :: Posi-Drain These models allow easy wiring to a remote solenoid valve and wall mounting. There were several on site already from the prior contractors installation, I just used one of them and claimed the rest for use elsewhere. The units are sold through air compressor distributors, with their individual house brand labels on the front. Many can be found on ebay.com used. The ones with the factory install valve are better than most due to the fact that they have a orifice with a sliding Delrin seal that wipes away contaminates.
Ebay samples,
POSI-DRAIN 110V DRAIN VALVE TIMER CONTROLLED AIR COMPRESSOR PART TITUS | eBay
ELECTRIC AUTO DRAIN 1/4" NPT 110V TIMER CONTROLLED AIR COMPRESSOR PART ''OEM'' | eBay
This system was installed ten years ago on a dirty old system, and has required no maintenance other than emptying, the oil collection container. Your needs may be less, but this system could be scaled down to meet a lesser need, and still be reliable, and no fuss.
SAF Ω