GGDT Design Library


Orbit WaterMaster
1" Sprinkler Valve
Modification

Perhaps the most popular valve in the pneumatic spud gun world is the Orbit Model 57461 Watermaster. They are cheap, plentiful, and easy to modify to pneumatic operation. Why do people modify them to pnuematic operation? Because such modifications dramatically improve the valve's performance in this application. Remember, sprinkler valves are not designed to open/close quickly. In fact, for sprinkler systems, opening quickly is bad as it can damage a sprinkler system. So if you want anything that resembles good performance from your sprinkler valve, you will modify it to pneumatic operation

If you're unsure of how to modify this valve, you've come to the right place! What follows is a step by step description of how to modify the Orbit WaterMaster for pneumatic operation.

Ready? Good. Let's begin....

  1. Buy yourself an Orbit WaterMaster. Take it out of the box and throw away that stupid solenoid! You should have something that looks like this...

  2. Disassemble the valve. You should end up with the five pieces shown below. Clockwise from the upper left I will call these pieces the retainer ring, spring, lid, body, and piston. Modification involves the lid only. The other pieces can be set aside for the time being.

  3. Using a Dremel tool, your teeth, or whatever else you feel is an appropriate tool (I am biased towards the Dremel), remove that chunk o' plastic on the bottom side of the lid. When done you've got this...

  4. When you were at the store buying the valve, you did pick up a 1/4 pipe nipple and a 1/4" ball valve, right? Well screw one end of the nipple into the ball valve. Don't worry about messing up the threads on the "other" side of the nipple; just grab it with a wrench and make sure it's in there good. Do it right and your reward is something that looks like this...

    Note: Blue Loc-Tite works GREAT for sealing metal on metal pipe threads. Much better than teflon tape ever dreamed of working.

  5. Using a bit of brute force if necessary, screw the nipple into the lid. It goes a lot easier if you use a tap and cut threads into the hole first (I always do) but this is not a requirement. The below pic should look very familiar to you about now...

  6. Unscrew the nipple that you just worked so hard to screw in. While you're at it, unscrew the bleed screw (the little back screw in the previous pic).

  7. Mix up a good amount of epoxy. I imagine any number of epoxies will work, but I use one that is intended for use with plastics. Coat the threads of the pipe nipple as well as all the interior threads on the valve lid (both the threads you made screwing the nipple in two steps back AND the threads that the solenoid used to screw into). The idea is to make sure that there is epoxy touching all thread surfaces. You don't want any air bubbles in there. Screw the nipple back into the lid until it just starts to emerge from the other side. Use epoxy to fill in any free volume you can see in the nipple/lid interface area. This epoxy is what is going to hold your valve together when you're done. Now is not the time to be stingy. More is better! While you're at it, take a couple drops of epoxy, slather them all over the bleed screw, and screw it back in the hole it came out of. When the epoxy cures you should have something that looks like this (top and bottom, of course)...

  8. Screw a blowgun onto the ball valve using another pipe nipple. When I made the one you see below I thought I would be taking it apart very soon (long story) so I used teflon tape. But don't let that fool you. Normally I use the Loc-Tite previously discussed.

    Oh, and most blowguns will have a flow restrictor (nozzle) screwed on the end of them. Remove it and throw it away.

    Note: that some people prefer a "remote" trigger and will use a piece of tubing to connect the blowgun to the ball valve. This allows the trigger (blowgun) to be placed elsewhere on the gun where it may be more comfortable.

  9. Remember when I said all the valve modifications involved the lid? Well, I lied. There is one last thing to do and it involves the valve body. If you look into the outlet port of the valve body you will see a small tube centered in the port. Under normal operation this tube allows the bleed air released by the solenoid to exit downstream. We don't want that to happen. Mix up another batch of epoxy and plug that tube! If the tube leaks, the valve won't work. When done, it'll look like this....

    Note: To aid in getting epoxy into the tube, it will help if you gently apply suction to the small metal tube exposed on the top of the valve body. This will pull epoxy into the tube.

  10. Reassemble the valve. It probably looks a LOT like this...

A couple final words...

Some of you may be wondering what the purpose of the ball valve is. It is the safety. When the ball valve is closed the gun will not fire even if the trigger (blowgun) is pulled. Open the ball valve and the gun is ready to fire.

This is not the only page out there that discusses sprinkler valve modification. I'm sure there are many. In fact, here is another. You might want to check out the other site (and any others you find) as I may have left out some neato tidbit that will come in particularly handy on your particular project.

If after reading all this you still have questions, then they will no doubt be answered by the goons over at the Spudtech Forums (but unless you like being abused, I suggest you read that first page before you start buggin' the goons).


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