Mist quality and tight control with long runs is perfectly possible.
Are you suggesting that as the line pressure drops, post solenoid closing, that you are maintaining "tight control" of the atomization? I promise, that no matter how stable you keep your pressure pre-solenoid, that once the solenoid closes, your atomization goes from 50 microns on the low side, to 80+ on the high as the pressure drops regardless of the initial burst.. So your chamber, in an HPA configuration, will never finish with the micron pattern it started with.
Also, in terms of initial burst pressure, if you have your demand switch set at 80PSI, the initial push into the static manifold will always be at least 80 PSI. During a 3 second feed time, you may see a drop to 60 PSI depending on where the pressure was and how quickly the pump picks it back up..
But in the end.. it doesn't matter. Whatever your initial pressure post solenoid is, once that solenoid closes, your line pressure will drop from it's peak down to zero and as it does, your mist pattern and atomization changes. Unless you have a solenoid right at the nozzle, the longer the run, the more the variation of the mist quality is as the volume is dispersed through the nozzles. More volume simply means a slower drop in pressure.
I get the impression you think we are starting with a lower pressure because we use a smaller accumulator. We will always start with at least 80PSI, because that's where the demand switch is set. Obviously if we start off at 100PSI, the accumulator may loose some pressure but not enough to kick the pump back on. That's why we go 2-3 cycles without the pump cycling.
It just seems ridiculous to strive for a certain initial pressure, when your finishing pressure will always be peak.. to zero. Thereby, no matter how hard you try, you will always have a higher micron figure hitting the plants. The only way to solve that is put a solenoid at every nozzle. That might be easy if your filling a shoebox with one nozzle.. but we are filling 32-64 cubic feet.
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with say 7 nozzles, will most likely fully pressurize when using a 1 second open time. However, the mist will run longer than 1 second due to the volume/pressure. Pressure is simply the energy that forces the volume through the nozzle. What comes out of the nozzle is dictated by both volume and pressure. I haven't done any testing to determine the pressure at which a Tefen nozzle no longer provides an atomized mist, however that is something I may try since I have a video camera capable of doing 240fps in HD. The point I'm making is whether one uses a 1 second, or 3 second open cycle, what truly dictates the mist cycle is the number of nozzles, thier flow rate and the volume/pressure within the line. It's quite possible that the difference between a 1 second and 2 second open time could be very minimal depending on the total flow rate of the nozzles. When it comes to mist quality though, you'll never achieve 100% micron consitency because as the volume is dispersed, pressure drops, thereby changing the pattern and micron size regardless of solenoid open time. 