Balanced valve is an awful term for the type of valve used imo in FX, RTI, and Epic, among some others, likewise RTI calling it an Assisted valve is also a terrible term because nothing is assisting it. The best term that describes it but doesn't 'sell' would be 'Pressure reduced valve' or some wordage similar to this, "Poppet holding force reduced valve" would be the most appropriate, which again isn't a 'sale phrase'.
Seen here is a 'Poppet holding force reduce' valve aka 'Balanced Valve'. The reduced force is displaced onto the piston OD that resides within the peek bored out poppet below. The height of the chamber is adjustable allowing the user to manipulate how much hammer strike is needed to create a certain amount of dwell, or to create a blow open style valve if adjusted for that. There is a vent that allows the bored out poppet section to reference atmospheric air, meaning inside that chamber while the valve is closed, you have ATM air acting upon its surface area opposed to your regulated pressure. One opened, the secondary function of the vent is to breathe enough air into the above mentioned volume to reverse the effects, returning the poppet to nearly a conventional state where closing forces are almost the same as a valve without the piston displacing any force, thus the inner chamber being at throat pressure / shot cycle pressure helps make this valve tunable, which is something I first discovered for the tuning community over at the GTA (vent size + chamber volume as solution to making these valves tunable via hammer strike)...however at that time FX was already using these in their gun, that doesn't mean they had it ALL figured out like what was done at the GTA, which allows far more manipulation of dwell than FX's design at the time.
Pilot valves are far superior to them. Because you can reduce the 'hammer slap' effect greater than any mechanically driven valve that I am aware of currently used in pcps. Quick animation shown how they *can* function here, based on a design both Dave and myself brainstormed:
Hammerless valve tech has been around for 7 years now and has yet to render mechanically driven valves obsolete...they are cool but, pilot valves are complicated enough and having 2 guns with PV's, I have no desire for something more complicated as seen in hubens, as my valves require VERY little hammer strike / slap and in its current state its inaudible. My regulated gun uses 4 grams of hammer 3-4 lb/in spring depending on tune, my unregulated gun uses 8 gram hammer with 4lb/in spring, both only require .45" hammer travel, or in other words around 1/6 the KE and 1/10th the momentum of the original gun that uses a conventional valve, and about 1/3 the KE and 1/3rd the momentum of a balanced valve.
More can be read here, but I covered a lot here on the BV with a good 'nuff summary.
Before I begin...Many thanks goes to Dave/ @sb327 for his contributions in getting me to where I am today with my current valve arrangement, we worked together closely to dial in versatile pilot valve that works very similarly to the one found in the L2. Also thanks to @csdilligaf for turning...
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-Matt