n this step we will modify an Orbit Model 57461
1" jar top sprinkler valve, making it a pneumatically actuated trigger valve. I found this particular model to have a number of advantages. It is the cheapest 1" valve I've found. The air valve is installed in the center of the cap allowing easy orientation of the trigger. Finally, the "jar top" construction makes it extremely easy to work on. Here is a link
to a page devoted to modifying this exact valve, I left out the safety ball valve in this design. Here is a link
to a visual explanation of how the sprinkler valve works.Trigger Valve Supplies
1 Orbit Model 57461
1" sprinkler valve
1 Blow gun
1 1/4" NPT pipe/hex nipple, like this
Dremel or drill
- Remove solenoid and bleed screw, they will not be needed Fig 1. Save the solenoid for future diabolical inventions.
- Disassemble valve by unscrewing the "jar" ring. Be careful, as under the top is a spring under tension.
- Cut, grind, or drill out the center of the top, make sure to leave enough plastic to thread the 1/4" NPT fitting into Fig 2. Grind or cut down the lip of material around the center hole to the level of the ribs Figs 3 & 4. This will allow you to get the fitting deep and tight.
- Use the 1/4" NPT fitting as a tap for cutting threads into the hole you just made, try to keep it as perpendicular as possible Fig 5.
- Once you have the threads cut, put Teflon tape on one end of the fitting and thread that into the blow gun Fig 6. Apply some thread locker to the other end of the fitting and tighten the whole assembly into the valve top.
- You are now ready to epoxy three places. A little dab in the bleed screw hole in the top, a little dab in the bleed hole at the valve outlet, and a good bit of epoxy around bottom and top of the brass fitting Figs 7 & 8. Try and leave the wrench flats of the fitting exposed and epoxy free in case you need to remove the blow gun at some point.
- Let the epoxy dry and then reassemble valve. The lever side of the valve should be underneath the outlet of the valve. Make the securing ring is as tight as possible.