Gate Valve Mystery

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Old 09-18-18, 07:59 AM
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Gate Valve Mystery

I had a lawn sprinkler valve spring a leak and I closed an upstream underground gate valve so I could replace the sprinkler valve. The gate valve wouldn't close tightly and when I cranked harder on it, the inside blocking flange came off the stem, I think. I opened the gate valve body, found the flange disconnected from the stem, but all still looked good inside. The flange came loose easily and I put the valve back together after some liberal silicon greasing. I turned the water back on and opened the valve. I got no water downstream of the valve. Shut the water off again, opened the valve, all looked good inside. The valve seems to crank easily. I noticed that a lot of water came out of the opened valve, indicating that water got past the valve ok. Put everything back together again. I still get no water downstream! I thought maybe there was an air lock in the downstream system, so I left a downstream lawn hose open for awhile. Still no water downstream.
Any one have a tip on how to proceed?
 
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Old 09-18-18, 08:37 AM
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Then there is something past the gate valve that is blocking water flow, another valve, or maybe the solenoids to the sprinkler zones?
 
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Old 09-18-18, 08:51 AM
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Well, I had replaced the bad sprinkler valve and opened its bleed screw to run the sprinkler manually, but still no water. Can't figure out what would totally block the system.
 
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Old 09-18-18, 09:53 AM
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I noticed that a lot of water came out of the opened valve, indicating that water got past the valve ok.
Are you sure that tells you water got past the gate? How do you know? Are you sure the gate is pulling up?

You may be 100% correct, I actually never took apart a gate valve (at least I don't remember lol) but I'm just wondering.
 
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Old 09-18-18, 07:22 PM
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All I can say is that all water downstream drained out when I broke open the valve, until there was no more flow. So if I put it back together, open the valve, then shut down and break open the valve again and about the same amount of water comes out, I'm guessing water is getting through.
But my next test is to take out the valve flange and see if I get water downstream. If I still don't, I think I have a big problem.
 
  #6  
Old 09-19-18, 08:47 AM
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Still not sure I understand the water past the valve part, however, if you turn on the main and you are getting no water downstream from the gate valve you repaired, even though you are cranking the handle on that valve to the fully opened position, then that valve is fully closed. If it were even partially open you would get a steady stream of water downstream from that valve, maybe a small stream, but steady.

It really sounds like the gate valve just isn’t opening. It sounds like the stem is broken and isn’t lifting the gate. I would replace it with a ball valve.

When you are taking that valve apart you should be able to pull out the stem with the disk connected to it and make sure nothing is broken. You should be able to turn the handle and watch the disk go up and down while connected to the stem.

In other words all of the moveable parts come out. You should then also be able to look down into the now empty valve body into the slot for the disk and determine if there is anything blocking the opening. When you say “opened the valve” I suspect you didn’t really take the valve apart.

Here is a good picture I found. Notice that everything pulls out of the valve body.
 
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Last edited by zoesdad; 09-19-18 at 09:44 AM. Reason: added picture
  #7  
Old 09-22-18, 07:26 AM
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Sorry, never occurred to me you may not know what a ball valve is. Here is a pic, and you can get threaded or sweat, whatever is easier. I think there is total agreement, replace gate valves with ball valves.


btw – I did find opened gate valves in my parts pile I had taken apart at one time (memory going fast –lol), and one is identical to the one in pic I posted in post #6. I’m sure I must have replaced those with ball valves. Yours may vary a little but the idea is the same. If the disk is detached you can use needle nose pliers to reach into the valve body and pull it out. If the innards are broken you can put the bonnet back on and thus have water until you are ready to do valve replacement.


(also when you say "break open the valve" you have to pull everything out to see what's actually going on, otherwise it's a guess)
 
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