SpudFiles

What would i select for a valve for a 3/4 sprinkler valve on the ggdt?

aka: valve type, flow coefeicency, seat diameter, dead volume, piston diameter, piston mass, vent diameter, and pilot volume

i know this is alot to ask but i really need some help

It's on both the page you downloaded GGDT from, and the wiki.

Very well, modderxtrodanare, except that it's NOT in those places.

The information for a 1" valve is, however.

Indeed, I don't think that anyone has ever taken those measurements for us.

However, if we want some numbers of questionable accuracy, we can always estimate them:

1" pipe has an interior diameter of 1.029"
3/4" pipe has an interior diameter of .802"

And so, let's assume that the 3/4" valve is .802/1.029=.779 times as large as the 1" valve.

Taking the measurements from D Hall's website and multiplying them...

Flow Coef: 23% (assumed to remain the same, use 23%)
Seat Diam: 1.2" * .779 = .94"
Dead Vol: 3.1 in³ * .779³ = 1.47 in³
Piston Diam: 2.0" * .779 = 1.56"
Piston Mass: 22g * .779³ = 10.4g
Vent Diam: .15 in (typical blowgun; remains the same)
Pilot Vol: 1.1 in³ * .779³ = .52 in³

We note that some of the .779s are taken to the third power - that is because the value we are multiplying them by depends upon the size of the valve to the third power.

alright thnx man