severe water hammer in sewage ejector discharge


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Old 01-04-10, 12:23 AM
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severe water hammer in sewage ejector discharge

I have a liberty pumps ejector pump with 2" discharge in basement. addition still under contruction and took all of kitchen and laundry in basement for temp use. no toilet being used down there. had lot of noise when pump would shut off and it blew one of the rubber sleeves holding check valve in place. also had leaks (that is another story-already posted about that!) plumber came and fixed the leaks, but still harsh when shuts off. blew off check valve again and the rubber seal in check valve got pushed almost out of valve. I took valve apart and put everything back where it should be and tightened it up good. reinstalled it in system and strapped some of the pipes that were moving. I ran some water and watched until pump came on. no problems when it started and was running, but shortly after it shut off, massive vibration in system. I would say it is water hammer. started checking the discharge line and it goes up about 18" then goes horizontal where there is check valve and then ball valve. it then turns up and goes to joists (about 7 ' 6") and then turns to horizontal. runs about 10' till it dumps into main sewage line. I think it had fall to the main sewer line but when I took level to it today, it now goes up slightly. I would think this contributes to the hammer and will call the plumber tomorrow, but getting him here has been a pain. even before he fixed the leak, there was lot of vibration on pump shut off so I don't know if getting correct fall in system will eliminate problem. I checked check valve manufacturer's site (legendvalve) and looks like they recommend a valve with compression fittings (instead of the rubber sleeves with hose clamps like the one on mine) for high vibration uses like 2" sewage pumps. so I could get one of those which may help prevent it from blowing off, but do I need arrestor? online looked like $150 for a 2" model, and I don't know if will work with sewage. would suspect it may get clogged. for time being, any problem with removing flapper so prevent it from blowing off till I can get plumber in to fix it?
 
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Old 01-04-10, 04:46 AM
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This is what I would do. If that check valve is horizontal I would mount it vertical.If you put a silent check valve in that will help alot. I also like a glue in check valve for sewage. Here's what I used in my house. (0823-20) Removing the flapper from your old valve will allow all the water left in the pipe to return to the pit when the pump shuts off, so it will run more often.T. Matera & Associates, Inc.
 

Last edited by pumpguy; 01-04-10 at 05:07 AM.
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Old 01-04-10, 08:18 AM
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what is silent check valve? I found the one you used. did search for that number. it is $44? The site I found doesn't say who manufacturer is? Can you tell me that? it has a spring in it. is that what makes it silent? I guess first I need to have plumber correct the pipes so it has fall after it reaches max height. then put something like this in. I understand the benefit of putting it vertically, but that may be hard since the pipe runs in 2x4 wall and that check valve won't fit there. It would have to go directly on top of the cover to get it vertically. I guess I could do that? liberty pumps said if that doesn't work to put in secondary check valve to break up the water column.
 
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Old 01-04-10, 04:08 PM
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The silent check valve eliminates the big clunk when the pump shuts off. The Magic plastics valve in the link has a nice solid plastic flapper with a spring that closes it. There is another type that has two rubber flappers inside, one on top with a slit in it and a regular flapper below. This slows the water to eliminate the clunk. We have had a few issues with the rubber flapper type, so I would recomment the Magic valve or similar type.

People are amazed how well these valves work. I put one in my house when we first got them, replacing a conventional valve and the difference was night and day. Builders have a habit of putting sump pits right underneath master bedrooms and we have made alot of people very happy with the silent valve. Some people like the clunk, then they know the pump is working-I'm not one of those people!!

You could try it horizontal. but I've seen some weird siphon problems with the valve like that. Vertical is better in my opinion.
 
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Old 01-04-10, 06:19 PM
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thanks. I was able to find that valve through ACE hardware online. local store didn't have it but could order it. was only $25 so I ordered one. maybe get a 1 1/2" for my sump pump as it clunks also. in meantime, I elimated the valve and just put a piece of pipe there. while changing it out, I shut ball valve, removed check valve, and then drained ball valve into bucket. I weighed it and have 15 lbs of water. so that is how much weight was slamming against the check valve and it had running start. some quick math calculations showed this to be about 1.8 gal and 11 ft of 2" pipe. measured pipe and that is length to the highest point. from there, water should fall to main sewer line. but as mentioned earlier, there is NOT fall into sewer from here. so I would have thought that I had more water going back to pit? I guess the velocity of the water is enough to shoot it over the horizontal stretch despite it being very slightly uphill.
 
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Old 01-13-10, 08:19 PM
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just to update, the plumbers came and redid the ejector line so that it went up to highest point and then had fall the rest of way to main drain line. they put the new check valve in and at my request put it vertical right above the sewege tank. I tested it out for first time last night. the pump came on and ran normally. then it went off and I held my breath waiting for the big bang that was knocking the check valve off and putting water in my basement-but it never came! the water that reached the peak flowed down to drain, the water that didn't went back to closed check valve but it didn't move at all. thanks for your help pump guy.
 
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Old 01-14-10, 04:24 PM
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Your welcome. I have those valves in my house and they work great.
 
 

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