Problème full auto !

[jackssmirkingrevenge]

Again, if you could show us pictures of your setup and components, it would be much easier to judge the issue.

[smirpab]

Sorry

[Lockednloaded]

how much pressure are you putting through the blowgun valve? if it is not much higher than your pop-off pressure, then you will get a hiss instead of a pop

[jackssmirkingrevenge]

Ah, so you're using a commercial valve as a pilot.

The only way you're going to stop it hissing at lower pressures is to get a higher rated one. You could also try adding some shims (thin washers, between the spring and the top nut, or between the spring and the piston) to your current one.

[smirpab]

Okay, thank you for your advice, but I think using a different technique;)

[Brian the brain]

The snapvalve will stop working completely if pressure falls too low.
But there is still a region where it hisses...not for very long though.

But if you modify your QEV so it can be filled from the chamber side you will have what you seem to want..


BENG_BENG_BENG and then complete silence..

It will make a much compacter configuration too.


Only rof will still drop...

Someone please translate...(??)

[jackssmirkingrevenge]

But if you modify your QEV so it can be filled from the chamber side you will have what you seem to want.

I can see how modding the QEV and filling from the chamber side will make it more efficient, but I don't think it would affect the performance of the pop-off valve.

[Brian the brain]

The pop-off wants to drain the pilot area while the blowgun tries to fill it...



That is counterproductive...It makes the pop-off act asif it were much smaller...

You want violent pressuredrop in the pilot area...

[al-xg]

CI= canon interne (internal barrel), it's weird jargon from the french forum, refering to the seat tube of a QEV, comparing it to a coaxial piston design where the barrel is also the seat for the piston.

The original post was asking about the relationship between the pop off piston seat diameter, piston diameter and porting diameter.

Although I haven't experimented with adjustable pop off valves, I have found that some just don't seem to pop and just leak. I once even fed 60bar into a 12bar pop off pilot and it still just hissed.

Ce que BTB a explique, c'est que le volume pilote doit etre minimal pour avoir une baisse de pression violente. Il suggere donc que tu modifies la QEV en ajoutant un ressort, pour avoir un remplissage par la chambre et donc un volume pilote plus faible.

(Above is just BTB's last post explained in french, sadly I'm using a qwerty keyboard (with blank keys ) and couldn't be bothered to add accents, so translators might not appreciate that.)

[jackssmirkingrevenge]

The pop-off wants to drain the pilot area while the blowgun tries to fill it...

That's true, but on the other hand, the feed from the blowgun makes the pop-off more violent, so it loses air at a faster rate than if it only had the pilot volume to open it.