SP Bel-Art Polypropylene Stopcock with PTFE Plug; for ¼ to ⅜ in. I.D. Tubing (F42040-0000)

has a slow leak, holds full vac for maybe 20 minutes, with a ~2 hour bleed to atmospheric pressure. it also takes much longer to pull to full vac through the tiny valve, which was clogged with milling burrs to begin with. overpriced for what is obviously cheaply manufactured. had much better luck with 15 dollars and the ace hardware plumbing section.its alright for what it is, if i only needed it to hook up a vac hose no big deal. on the other hand if you want it to do what its intended, and hold negative pressure, find another part.

I really wanted to give this Stopcock a Two Star rating but I gave it a three because mine lasted for a year before I had to replace mine and i pretty much use it on a weekly basis.The trick I found to using these, is to keep the bottom nut tightened while under full vacuum pressure.But what happens over time is the "thin" plastic threads eventually stripped.I REALLY wish they'd improve this item by making it more solid. Especially the threaded end bottom piece.

i just recieved a Bel-Art Scienceware 420430000 Polycarbonate/PTFE Vacuum Chamber with ABS Plastic Plate, 9" Diameter x 6-1/4" Height and the valve broke on both the stopper end, as well as the connecter end upon the first use when hooked up to a 2 stage 5cfm pump. the only way i can achieve a vacuum level of -29hg is to have this loud pump constantly running. this thing literally broke on the first use and you want $40 outta me for a new one? this has got to be a joke.