Pop off valves
Posted: Wed Feb 08, 2012 8:53 pm
With pop off valves do they just pop once and let the extra air out in 1 go or will it pop numerous times letting the pressure ?
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Posted: Thu Feb 09, 2012 12:05 am
numerous times and then they reseat themselves, you can either pull them manually or they go off at a preset pressure.
Posted: Thu Feb 09, 2012 12:20 am
not 100% sure on this but when my buddy pulled his open it stayed open until he pushed it closed
Posted: Thu Feb 09, 2012 12:27 am
They only self-close when the "pop-off" pressure is no longer present in the tank.
pop-off_true = If pressure in tank > pop-off pressure
Your also likely to experience a bit of hysteresis in a pop-off valve due to the mass flow of air.
pop-off_true = If pressure in tank > pop-off pressure
Your also likely to experience a bit of hysteresis in a pop-off valve due to the mass flow of air.
Posted: Thu Feb 09, 2012 12:28 am
some are built that way and some are built with a spring to allow for reseating.
Posted: Thu Feb 09, 2012 12:54 am
In short, if you want pop-pop-pop-pop, you need to be feeding air into a tank at a slightly slower rate than the pop-off can empty it.
Posted: Thu Feb 09, 2012 4:38 am
how do i do this ? smaller ports to reduce flow?jackssmirkingrevenge wrote:In short, if you want pop-pop-pop-pop, you need to be feeding air into a tank at a slightly slower rate than the pop-off can empty it.
has anyone played around with this particular type of pop off ?
http://www.ebay.com.au/itm/80-PSI-AIR-C ... 814wt_1110
Posted: Thu Feb 09, 2012 4:47 am
You could also make something like this:
The air from the tank is fed into the inlet of the pop-off valve, the oulet of the pop-off valve is fed to the pilot volume, and the threaded port of the pop-off valve is also connected to the pilot volume.
The air from the tank is fed into the inlet of the pop-off valve, the oulet of the pop-off valve is fed to the pilot volume, and the threaded port of the pop-off valve is also connected to the pilot volume.
Posted: Thu Feb 09, 2012 5:10 am
hrmmmm looks quite good. I do like how its more efficient but with my lack of resources could prove a bit challenging to make
Posted: Thu Feb 09, 2012 7:13 am
Yeah, the drawing does not reflect practical solution for manufacturing.
JSR has made many similar systems with some bits of tube and epoxy resin.
I reckon one could even make a copper pipe/brass fitting/soldered version also.
JSR has made many similar systems with some bits of tube and epoxy resin.
I reckon one could even make a copper pipe/brass fitting/soldered version also.
Posted: Thu Feb 09, 2012 8:28 am
and rubber bands and lollypop sticks...al-xg wrote:JSR has made many similar systems with some bits of tube and epoxy resin.
Posted: Fri Feb 10, 2012 3:07 am
looking at the pop off al-xg posted i though it would be a little difficult to fit onto an airgun without it being awkward due to the air inlet and outlet so i threw this sketch together of an inline popoff based on the previous one... any flaws?
Posted: Fri Feb 10, 2012 6:29 am
How are you going to get the spool in the body?
Posted: Fri Feb 10, 2012 6:43 am
i would make these 1/4 threads... i could probably tap one side ,insert the spool and spring and then add the nipple and then solder it in
Posted: Fri Feb 10, 2012 8:50 am
Yes there is a problem, the piston isn't balanced.
The air from the tank will be pushing the piston to the left helping the spring.
Because it has a larger area to push on than the pilot side , the pop-off valve will never fire.
The air from the tank will be pushing the piston to the left helping the spring.
Because it has a larger area to push on than the pilot side , the pop-off valve will never fire.