VR25-100 VR Series Brass Vacuum Relief Valve - 1/4" Male NPT, 0-30" Hg Vacuum Range for HVAC, Industrial Automation & Laboratory Equipment

It's hard to find good Schrader valves with weak enough springs for water well service. These vacuum breakers are adjustable.I have an application with an electronic variable vacuum adjustment. I wanted something to use as a "fail safe" so that if the electronic regulator failed, it would still not pull more than a specified level of vacuum to avoid damage to the system. This gizmo fits the bill perfect. I was able to set it to just above the maximum vacuum the regulator is supposed to allow. If the regulator doesn't do it's job for whatever reason, the valve opens and prevents over (vacuum) pressurizing.Setting the pressure can be a bit fiddly, but as long as you don't need to be super precise it's easy enough to get it adjusted.I ordered 3 of these valves and they arrived individually sealed which was nice. The first one I was able to install to a 1/4 inch connection without problem and it held about 28inhg to 29inhg vacuum. I was unable to get anything significantly over 25,000 microns... Being somewhat pleased with the first valve I went to install the second one. This one had more of some rubber spray they sprayed at the bottom and when I tried to tighten the valve down past the rubber to make what I though was a good seal the whole valve housing deformed and pinched the adjustment screw making it nearly impossible to adjust without pliers... The kicker was because I didn't test the second valve before I installed it, I assumed it was defective. I tested the adjustment on the third valve before I installed it and it was working perfectly... The third valve also had tons of rubber on the bottom. Thinking the second attempt had just been a bad product, I attempted to tighten the valve past the rubber spray on the threads and not only split the pipe I was screwing the valve into (because of this crappy rubber spray), but crushed the valve housing again making the once working adjustment screw stop working...I would make sure you burn off the rubber spray on these things if you have to use them and just seal them with a good teflon tape, or just LIGHTLY hand tighten these... The housing is so soft, that just a medium hand torque was enough to bend the housings... These things would be perfect if they removed the rubber and made a heavier duty version that could handle high vacuum...I am very disappointed and had I known they were so cheaply made I would have tried to find a stainless steel version first... I basically just threw 15 bucks down the toilet...Its thin, don't torque it too hard or the body will bend, then you won't be able to adjust it. Its a large 1/4" npt, so it won't screw in far. I thought it was just getting a little tight in the thread sealer but it was the taper and I bent mine before I knew it. But using channel locks, I was able to get a little adjustment and it worked just like I wanted. I was able to maintain a light 5inHg. The valve opens early, just a crack, then more as vacuum builds towards your preset. Since I bent it, im gonna buy another, just be careful.Regulates our vacuum line to the proper pressure.I used this to release pressure from a catch can on a turbo system. Well made unit but hard to get below 5psi pressure release so I cut the spring to make it work like I needed.No experience but does what I expectedNo complaints, it works