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MadMax · December 5th, 2015, 02:36

We employ a two port fill valve in our grenade design. Jabba wabbo hoodah thing that you do it with.

It's not jargon. Our fill valves open two ports when you fill. One port conducts liquid into the grenade reservoir. The other port allows the escape of gas from the resevoir which at first blush seems counterproductive.

What most players expect is a fill valve that isn't apparently leaky. It quietly accepts fill through a single passage connecting the propane tank.

The problem with single port fill valves is that they only allow liquid transfer from tank to device until device reservoir pressure equalizes with tank pressure. It is possible for reservoir pressure to equalize with the tank before you have transferred enough liquid. This issue is more likely if your tank temperature has gotten cold after say filling a few GBBR mags. It is especially likely with devices that need a high liquid proportion of the fill capacity of their reservoir as Cyclone does.

What a 2 port fill valve does is to vent some gas from the top of the reservoir to permit the continued transfer of liquid into the reservoir. This first stage of fill will sound leaky. When sufficient liquid has been transferred, it flows up an overflow feature which lets liquid to escape. This 2nd stage of fill pishes out a white mist of liquid from the valve which prevents overfilling. You do not want to fill a reservoir chock full of liquid leaving no gas space which is the other intent of the overflow feature. It preserves a minimum gas space which prevents the reservoir from developing a very high pressure when it warms back up again.

With a single port valved reservoir, it is possible to achieve very high fill proportion if you chill the reservoir first, but even without the explosion issue, you will not reserve any expanded gas volume for a device like a GBB to operate from. Your first shots will be weak and blast out a lot of liquid mist. It may even not have enough sustained pressure to operate properly until you've blasted off several shots of liquid.

I didn't invent the 2 port fill valve. It is a common feature of nearly every Japanese airsoft gun which is one of the reasons they operate more consistently than some Taiwanese guns that employ single port valves. You always get enough propellent into a TM mag with a leaky seeming fill valve and your first shots are punchy because they have an appropriate amount of expanded gas to work from.

Fill until you see a white mist coming out of the valve which indicates that your reservoir is done.

December 5th, 2015, 02:36	#8
MadMax Delierious Designer of Dastardly Detonations Trader rating Join Date: Dec 2001 Location: in the dark recesses of some metal chip filled machine shop	We employ a two port fill valve in our grenade design. Jabba wabbo hoodah thing that you do it with. It's not jargon. Our fill valves open two ports when you fill. One port conducts liquid into the grenade reservoir. The other port allows the escape of gas from the resevoir which at first blush seems counterproductive. What most players expect is a fill valve that isn't apparently leaky. It quietly accepts fill through a single passage connecting the propane tank. The problem with single port fill valves is that they only allow liquid transfer from tank to device until device reservoir pressure equalizes with tank pressure. It is possible for reservoir pressure to equalize with the tank before you have transferred enough liquid. This issue is more likely if your tank temperature has gotten cold after say filling a few GBBR mags. It is especially likely with devices that need a high liquid proportion of the fill capacity of their reservoir as Cyclone does. What a 2 port fill valve does is to vent some gas from the top of the reservoir to permit the continued transfer of liquid into the reservoir. This first stage of fill will sound leaky. When sufficient liquid has been transferred, it flows up an overflow feature which lets liquid to escape. This 2nd stage of fill pishes out a white mist of liquid from the valve which prevents overfilling. You do not want to fill a reservoir chock full of liquid leaving no gas space which is the other intent of the overflow feature. It preserves a minimum gas space which prevents the reservoir from developing a very high pressure when it warms back up again. With a single port valved reservoir, it is possible to achieve very high fill proportion if you chill the reservoir first, but even without the explosion issue, you will not reserve any expanded gas volume for a device like a GBB to operate from. Your first shots will be weak and blast out a lot of liquid mist. It may even not have enough sustained pressure to operate properly until you've blasted off several shots of liquid. I didn't invent the 2 port fill valve. It is a common feature of nearly every Japanese airsoft gun which is one of the reasons they operate more consistently than some Taiwanese guns that employ single port valves. You always get enough propellent into a TM mag with a leaky seeming fill valve and your first shots are punchy because they have an appropriate amount of expanded gas to work from. Fill until you see a white mist coming out of the valve which indicates that your reservoir is done. __________________ Want nearly free GBB gas?