Thanks @PWProducts. I see what you are saying about union metering valves, but I haven’t run across any metering valves that aren’t union style. Are you aware of any?
Also, can you and others look through my basic P&ID sketch and give me your thoughts?
Here is the text version: 3 incoming lines. SH. Water. Soap. SH and water are supplied by 1" polybraid hose and go to 1" PVC barb on the inlet of the metering ball valves. Soap is supplied by 1/4" polybraid hose and goes to a 1/4" PVC barb on the inlet of the soap metering ball valve. All three metering ball valves are 1". There is a 1" Hastelloy check valve after each metering valve. SH and soap have a 45 degree elbow to a 1" barb, and water has a 1" barb with no elbow right after the check valves. From these 1" barbs there is 1" polybraid connecting all 3 lines to 1" barbs on a black PVC double wye with a 1" barb on the outlet. All fittings are PVC, not polypro.
If I’m looking at this right, this is most efficient way to direct 3 liquids into 1 line with the least restriction. There are no 90 degree turns, and having polybraid hose in the middle of the unit would allow operators to visually check that their mixes are pulling at the actual device and not just incoming lines going into a covered box.
One possible alternative to this would be to use 1/2" or 3/8" fittings, metering valve, check valve, and hose for the soap line since that is such a small portion of the mix. It seems to me like 1" might be too large and could cause problems this way? Can you give me some feedback? But in my opinion at this point, this layout is the simplest and least restrictive, even if the soap line should be downsized.
In case anyone didn’t know, this is a black PVC double wye. Though it doesn’t have all the same inlet sizes, I’m sure I could find one with some searching.