how long should pressure remain in cylinder?

I’m wondering hot long the pressure should remain inside the cylinder once it’s been pumper to the desired hg? I just built a homemade system with a gravel cleaner and the pressure only lasts a few seconds before it starts to escape - my hand is killing me from the continuous pumping.

With a good seal it should last 30 seconds to several minutes depending on just how air tight your set up is. If you are continuously pumping, you have a leak to fix somewhere.

I use a (mostly) homemade system and the vacuum will last for as long as I’m planning to stay in the cylinder. I agree with gprent, you’ve got a leak somewhere.

I use an commercial one and it takes about 30min for it to leak from 4inHg to 0inHg. You may wish to check all connections, and also the seal between the cylinder and your body. You do have a good seal, don’t you? Shaving helps a lot.

Try an inner tube for the seal, and I use the non scented gun oil from adult novelty shop, as a helper lube.. I get hung up

I am still getting my rhythm for pumping. Today was my first day pumping and I ran into the same issue and I need to fix it. How hard should I have to force the male coupler into the female coupler? At first I tried to pop it right in but it would not go in. I had just bought the pump and did not want to break it by applying to much force, but eventually I just went ahead and forced the male coupler into the female coupler. I don’t know how tight the connection should be there, but that is my best guess as to where my leak might be. I am pumping with a Picturebrite pump with gauge.