sb,

You are knowledgeable enough with your experience to inform us about the particulars and clear the smoke and mirrors for us non-professional blokes. A matrix of definitions, pros and cons would be nice. Aloha

I appreciate your confidence, but I fear it is misplaced. I'm asking questions, not providing much in the way on answers.

I can handle a few things now.

Flow control: In a nut shell it has a faucet handle. (mostly, some are just screw/bolt heads) You want this if you have zones of sprinklers (50-60 psi) and drip irrigation (20-30 psi) on the same system. You can adjust the flow to the point where you have enough water to drip, but not so much as to blow out the myriad joints of small tubing. Properly this should be done with a pressure regulator. Flow control also allows you to shut off a zone if a valve sticks open.

Flushing filters. Valves work by using a small amount of water to actually move the main part of the valve. Dirt in this water means the valve sticks. A filter keeps the dirt out of the operating part of the valve. If it's flushing, then part of the normal operation of the valve is that water is pushed backward through the filter to dislodge the crud. I don't think that the main stream of water is filtered.

The big advantage of this: You can use otherwise crappy water. Expecially true for running sprinklers, which are tolerant of grunge. You can pump water from a dugout, filter out the algae and the goldfish, and pump the rest through your system. Note: Drip irrigation is VERY fussy about grunge in the water. 150 mesh, sometimes 200 mesh filters are usually called for.

Haven't found a good reason for angle valves yet, except the possible space saving in the valve box. A straight through valve can have lower friction losses, depending on internal water path.

Another feature I'm looking for now is 'slow closing' Valves use the water pressure to move the actual flap or diaphram. Think door closing in the wind. The solenoid gets it started, or opens a tiny port for water to flow, then, WHAM.

In my case this is not good. My trees are a thousand feet from my house. That's 1000 feet of 1.5" water line -- It takes about 100 gallons of water to fill the line -- so that's close to half a ton of water moving at a couple feet per second that you are trying to stop. Slow closing allows this to happen a bit more gradually.

It's enough of a concern, that I have an extra pressure tank that I picked up cheap at an auction. I'm planning on putting it at the end of my mainline so that when a valve closes on a branch line, that 1000 foot long slug of water has someplace to go.

Materials.

Begin Rant:

I have a personal vendetta against PVC. While innocuous in use, it is very difficult to dispose of safely. A very small amount of PVC in a batch of otherwise recycleable plastic ruins the entire batch. When it burns the gasses are deadly poisons, and tough on the environment. (True generally about organic materials containing chlorine) The additions to the plastic to make it flexible are toxic in their own right. And then there's the heavy metals used to make it stronger. And it falls apart after several years in the sun.

Rant done.

Glass filled nylon is another material used for valves. Recommended. Nylon is not tough on the environment, either in the making or the disposal. Glass filled means they've added glass fiber to give it strength and dimensional stability. Usually they will also add enough powdered carbon to make it black. This absorbs UV so that it lasts far longer in the sun.

Couplings can be slip, for gluing, threaded with standard pipe thread, or barbed for use with polyethylene.

Replacing a glued in valve is a pain. You have to cut the joint. Now you have pipes that were shorter than they were, so you have add a chunk. And you are doing this in confined space in the valve box, hunched over, and probably kneeling on a patch of gravel wearing shorts.

You want threaded fittings. If you run thin wall tubing to the valve, you can get compression to threaded fittings. This in effect has a built in union, as a compression joint will rotate, but not slip off. If you don't use compression joints, then ONE side of the valve should have a union (A joint that allows rotation of one side of the joint while still able to make a seal. If your valves are crowded enough that you can't spin them in place to unscrew from the existing plumbing, you want union fittings on both sides.

Because of my dislike for PVC, I use polyethylene pipe. For sprinklers I use conventional water pipe, for drip irrigation I use thinwall tubing and compression fittings.

Advantages: No joints. Flexible. Tolerates freezing even with water in them. (The connections don't tolerate freezing when filled with water -- So set up your system so that connections are a few inches higher than the pipe on either side. Even bad draining for winter will leave them dry.

Downside. Flexibility means it doesn't stay put very well. You will need to buy buckets of barbed to threaded or compression to threaded adapters.

Another thing that came up is that not all valves operate well at low flow rates. There is a reason for reading the spec sheets.

Mike, you have a lot more experience than I do on this, please feel free to add to this, and tell me wehre I am wrong.

My only question is about the extra pressure tank. Will it be an above ground installation. An extra tank like this can't hurt because it allows the valves to draw from a reservoir but a pressure regulator on the main line may be more efficient at stopping the water hammer.

sb,

You have proved my point and not timid about expressing your opinions either. Great stuff. A diary of experience. You can help a myriad of gardeners wondering about what the details are all about. It always can be done better. Enjoyable to read. Aloha