I believe Stanley meyer told us about the speed of the explosion of the gas also in relation to his quenching circuit. I believe you must have the tubes thin enough to pass the gas from a gas source of a determined pressure at a speed higher than that of the burning speed of the oxygen and hydrogen. This way the flame can't come back. And the fuel with its oxidizer can travel safely. You just have to know the amount of the gas to pass thru it, it's density, the holes sizes and the pressure differential. I didn't found the calculation yet but is all about this. Even a 10-mm long Quenching circuit is enough to prevent the cell from explode if you determine your electronics to work in a manner as to maintain the pressure constant you can be 100% safe.