# Possible Air Lock



## hulihan (Aug 11, 2009)

Hi all,
I have a problem and I will try to describe as best as I can, we Hydro Jetted a lower parking garage about 2 to 3 months ago, the parking garage is about 150 feet wide and about 300 plus feet long, at the end of each side there are sump pumps, in the middle of the garage there is two pits, one goes to one sump pump and one goes to the other, the pits/catch basins are about 14 inches deep by about 24 inches square, the drain line from each pit to the sump pump is 1 1/2 at the pit and 2 inch at the sump pump pits. Yesterday we were working on the fire sprinklers and we drained all the water from the sprinklers, the water only went to one catchbasin/pit, once the water dumped from the drain down from the fire sprinklers very fast, and once it was going down the pt all of a sudden, it started bubbling like it was gasping for air, is it possible because it is such a long run with no vents, that the water is air locking and that is why it is not draining fast ? The owner is complaining that we did not doa goood job hydrojetting, I just said we would take care of it, sorry for the long story, but can it airlock because of the distance ?
Craig


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## Protech (Sep 22, 2008)

no. air lock can only happen if the hydraulic gradient is broken.


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## Plumber Jim (Jun 19, 2008)

camera the lines and see if you have them open. If you do then show the videos to the owners.


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## hulihan (Aug 11, 2009)

Thanks, we are going to camera them and show the owner, but it was weird how the bubbles, or big air pockets happened, the water ran perfect for the first minute or so, and then, it just stopped and then started again ??? the pump workes perfect, check valves etc.... Weird, but we will figure it oout, just wanted to see if anyone on here had experienced it and might say, funney that happened to me


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## uaplumber (Jun 16, 2008)

Too much water too fast. The pipe is undersized for that amount of flow.
It is not meant to act as a fire line drain.


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## Plumber Jim (Jun 19, 2008)

uaplumber said:


> Too much water too fast. The pipe is undersized for that amount of flow.
> It is not meant to act as a fire line drain.


 
That too. 1 1/2" sounds small.


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## hulihan (Aug 11, 2009)

We know it is not a fire line drain and we know it is to small , it has been there for awhile, just wondering why it seems to be air locking, but no worries, we will figure it all out when we get to it in a couple of weeks !


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## 422 plumber (Jul 31, 2008)

It ain't airlock.


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## M5Plumb (Oct 2, 2008)

Seems the piping is undersized going to the sump, this is in a parking garage right? Possibly a belly in the piping... What's to say some piping freezes, ruptures and floods the place, how is the sump going to keep the rate of flow with the inlet piping sized as it is? 
What's the depth of the inlet to the sump? What's the drop from the inlet to the sump, does that add up with relation to where the 1-1/2" line ties in to the sump?



hulihan said:


> Hi all,
> I have a problem and I will try to describe as best as I can, we Hydro Jetted a lower parking garage about 2 to 3 months ago, the parking garage is about 150 feet wide and about 300 plus feet long, at the end of each side there are sump pumps, in the middle of the garage there is two pits, one goes to one sump pump and one goes to the other, the pits/catch basins are about 14 inches deep by about 24 inches square, the drain line from each pit to the sump pump is 1 1/2 at the pit and 2 inch at the sump pump pits. Yesterday we were working on the fire sprinklers and we drained all the water from the sprinklers, the water only went to one catchbasin/pit, once the water dumped from the drain down from the fire sprinklers very fast, and once it was going down the pt all of a sudden, it started bubbling like it was gasping for air, is it possible because it is such a long run with no vents, that the water is air locking and that is why it is not draining fast ? The owner is complaining that we did not doa goood job hydrojetting, I just said we would take care of it, sorry for the long story, but can it airlock because of the distance ?
> Craig


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## hulihan (Aug 11, 2009)

I will find all that out, the place was built in the late 70s, there are concrete patches in quite a few places that would seem to be the line the drain is following, it is by the beach, so no freezing here  The new owners who we work for, bought it about 4 or 5 yrs ago, just puzzling, but once we camera and play for a few hours, I will report back, all the obvious stuff, we already know, just like I said, wanted to see if we were missing something, might even take a pic or two and post up, then you guys would get a better idea of what I mean !


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## 422 plumber (Jul 31, 2008)

Airlock is what the diyer's on the other forums are sure they have, either in their water lines or in their drain lines, depending on the situation.


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## TheMaster (Jun 12, 2009)

Cavitation means that cavities or bubbles are forming in the liquid that your pumping. These cavities form at the low pressure or suction side of the pump, causing several things to happen all at once:

The cavities or bubbles will collapse when they pass into the higher regions of pressure, causing noise, vibration, and damage to many of the components.
We experience a loss in capacity.
The pump can no longer build the same head (pressure)
The pump's efficiency drops.
You say the sumps are 14" deep....that seems shallow. Then again I might not know what i'm talking about. Just speculation as to a possible problem.
......................................................................................................................................................
After re-reading I think your catch basins are 14" deep not the pump pits.....how deep are the pits the pumps are in? I still think cavitation may be your problem.


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## hulihan (Aug 11, 2009)

The pits the pumps are in are about 7 feet deep, maybe a tad more, I am going to take a couple of pictures and post next week ! It is obvious it was set up wrong from the getgo, maybe even added after the garage was finished/concrete at least, not sure, but there are so many things that do not belong, so I will take my camera and tak a few pics and put them up, next week at some point.


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## TheMaster (Jun 12, 2009)

hulihan said:


> The pits the pumps are in are about 7 feet deep, maybe a tad more, I am going to take a couple of pictures and post next week ! It is obvious it was set up wrong from the getgo, maybe even added after the garage was finished/concrete at least, not sure, but there are so many things that do not belong, so I will take my camera and tak a few pics and put them up, next week at some point.


 How much water is left above the pump after it cuts off?


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## hulihan (Aug 11, 2009)

Just enough so the float does not turn the pump back on, check valve and all ! We will be working back at that shopping center later this week or early next week, I will take my camera !


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## hulihan (Aug 11, 2009)

Well, tomorrow we will begin playing with this mess, got to busy and put it on the side burner, will let you all know what we find, got that new little mini rigid camera, only has 30 feet, so 25 or 27 of usable camera, I will keep you posted on what we find, but I already know the problem I think , most here were right ! So once we check it out more in depth, but to small of a drain line, belly for sure and maybe messed up.


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## M5Plumb (Oct 2, 2008)

Given that info, and the pump's efficiency curve, how long does it take to pump the effluent out? If the cross curves show the pump delivering within the cross curves established, and you get cavitation, TM has it nailed. The suction is too small or the distance to the pump head is too long in too narrow of a supply line in order to flood the head space. = Cavitation !! 





TheMaster said:


> How much water is left above the pump after it cuts off?


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## hulihan (Aug 11, 2009)

We did not get to it, hopefully soon, the owner wants to do something that makes no cents, so we will wait awhile, probally till it rains and then they will freak out because it takes days to pump out, that is when they will want to fix


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## plumbwright (Oct 26, 2009)

Do the sumps that contain the pumps have an air tight lid? If so are they vented?


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## bchplumbing (Oct 24, 2009)

Can you camera a 1 1/2 drains? i thought 2" was the smallest.


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