ContractorDave
Mechanical
One star for the obvious and two stars for the not so obvious with an explanation.
Regards
Dave
Regards
Dave
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What's wrong with this picture? 1
- Thread starter ContractorDave
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- #3
It looks like a backflow preventor with a downstream expansion tank with a closed drain valve. There is also an upstream ball valve which is closed.
This might be a limited area system off a domestic water system.
The upstream valve might be closed since the sprinkler system has not been tested yet and the domestic system has water in it.
The expansion tank is being used to compensate for pressure increase in the downstream sprinkler piping - although why it would be needed is uncertain.
This might be a limited area system off a domestic water system.
The upstream valve might be closed since the sprinkler system has not been tested yet and the domestic system has water in it.
The expansion tank is being used to compensate for pressure increase in the downstream sprinkler piping - although why it would be needed is uncertain.
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- #5
ContractorDave
Mechanical
Not quite PEDARRIN2. The fitting with the sprinkler head hints at the real problem here. ... Where's the backflow specialists?
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1
- #6
The backflow prevention unit is installed backwards (flow arrows from sprinkler system to the supply rather than supply to sprinkler piping).
The backflow prevention device is also a RPZ (reduced pressure zone) style which is designed to dump water from the middle bottom port when a backpressure event occurs; there is not drain piping on this RPZ.
It also looks like the sprinkler head has been leaking based on the rust under the head and relatively new steel pipe upstream and downstream.
The white tank appears to be some sort of an attempt to trap air in the system piping? Is that an air line connection controlled by the red handled valve with a check valve between the white tank and the system piping?? Looks like someone tried to install a dry system with no air compressor..........maybe the air kept on dumping due to higher pressure on the downstream side so they flipped the backflow device to resolve the problem! HA HA
The only other possible problem I see is that the system does not have a low point drain.
I am fairly confident this sprinkler system deserves a RED TAG (primarily due to the oreintation of the RPZ Backflow prevention device)!!
The backflow prevention device is also a RPZ (reduced pressure zone) style which is designed to dump water from the middle bottom port when a backpressure event occurs; there is not drain piping on this RPZ.
It also looks like the sprinkler head has been leaking based on the rust under the head and relatively new steel pipe upstream and downstream.
The white tank appears to be some sort of an attempt to trap air in the system piping? Is that an air line connection controlled by the red handled valve with a check valve between the white tank and the system piping?? Looks like someone tried to install a dry system with no air compressor..........maybe the air kept on dumping due to higher pressure on the downstream side so they flipped the backflow device to resolve the problem! HA HA
The only other possible problem I see is that the system does not have a low point drain.
I am fairly confident this sprinkler system deserves a RED TAG (primarily due to the oreintation of the RPZ Backflow prevention device)!!
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- #7
ContractorDave
Mechanical
One star for FFP1! The RPZ is indeed installed backwards. And though there is no air gap drain installed here, the problem isn't the drain but the expansion tank. It's maximum rated working pressure is 150psi. Attached is a pic of another glycol loop where the expansion tank failed.
Dave
Dave
chevy4x4trucks
Mechanical
Looks like a residential expansion chamber. Also, I don't see a valve to isolate the expansion chamber for maintenance Figure 7.5.3.2 NFPA 13 - 2002 Edition.
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- #9
ContractorDave
Mechanical
There did happen to be a valve there. I recently changed out a Watts 150psi WP tank for a Young Engineering unit for an SNC Lavalin asset. The thing was built like a bomb, weighed a ton, and cost 24 times what the Watts goes for. And you wonder why you never see them.
Dave
Dave
sprink131371
Mechanical
Looks like the sprinkler head may be slightly obstructed from developing a full spray pattern.
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- #11
ContractorDave
Mechanical
Hmmmm. fair enough. It WOULD be better if that were a pendant wouldn't it?
Dave
Dave
SprinklerDesigner2
Mechanical
Not to be picky but I always hated the look of plumbers strap on sprinkler systems.
Not sure but don't expansion tanks need to be mounted vertically?
Not sure but don't expansion tanks need to be mounted vertically?
chevy4x4trucks
Mechanical
SprinklerDesigner2 - You should be able to mount the expansion tank vertically, but as said before if the one that was installed was inexpensive then it definetly was not listed for fire protection use. The FP ones are about $800 for a small expansion tank.
sprink131371
Mechanical
"Attached is a pic of another glycol loop where the expansion tank failed." lightecho (Mechanical)
If this is a glycol loop, where is the fill cup? I suppose that you could use the 1/2" ball valve after the expansion chamber to fill the system with antifreeze.
Also shouldn't there be another isolation valve on the discharge side of the backflow for servicing or is it there before the gauge and I can't see it because of the orientation of the picture?
If this is a glycol loop, where is the fill cup? I suppose that you could use the 1/2" ball valve after the expansion chamber to fill the system with antifreeze.
Also shouldn't there be another isolation valve on the discharge side of the backflow for servicing or is it there before the gauge and I can't see it because of the orientation of the picture?
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- #15
ContractorDave
Mechanical
There is no fill cup or provision for one, there is no upstream isolation valve, The expansion tank was the only means of pressure relief, the existing OS&Y is not tampered or otherwise sealed in the open position, there is no RPZ anywhere between this glycol loop and the domestic supply.... and those were just the problems with the glycol loop.
SprinklerDesigner2
Mechanical
How about NFPA 13 climb move out of the year 1909 getting rid of anti-freeze systems entirely?
*If* you do one the *right way*, with a UL listed expansion tank etc, putting in a small dry pipe system would be nearly as cheap while saving the customer headaches every year forever.
I don't do anti-freeze loops and haven't for 15 years.
*If* you do one the *right way*, with a UL listed expansion tank etc, putting in a small dry pipe system would be nearly as cheap while saving the customer headaches every year forever.
I don't do anti-freeze loops and haven't for 15 years.
ChrisConley
Mechanical
Can you give some more background on that SD2? We use an anti-freeze loop on just about every project we work on. I'm located in Canada, and the majority of the use is small zones near overhead doors.
For us, it's a lower maintenance solution than a dry pipe zone, fewer pipe corrosion issues than dry pipe... generally cheaper too.
SprinklerDesigner2
Mechanical
Chris,
I'm near Florida so it's warmer and seeing how it seldom gets below freezing we don't have to fret aver zones near overhead doors. Coldest I've seen it in past 4 years was 24 F and that was cold enough for me.
When I do see anti-freeze systems they tend to be larger than one or two heads.
The cost of an RPZ backflow prevention assembly (EPA required here) plus added to the cost of the expansion tank adds to the cost along with the anti-freeze at $10 per gallon etc.
Annual testing on the backflow will run $100 per year (must be done by someone certified in testing backflows and sprinklers) and that goes on forever. Add to this the cost of draining/re-mixing the anti-freeze and I wouldn't touch the smallest one for less than $250 per year total. This goes on forever.
Yes, they are cheaper but I'm opinionated and don't like them.
I'm near Florida so it's warmer and seeing how it seldom gets below freezing we don't have to fret aver zones near overhead doors. Coldest I've seen it in past 4 years was 24 F and that was cold enough for me.
When I do see anti-freeze systems they tend to be larger than one or two heads.
The cost of an RPZ backflow prevention assembly (EPA required here) plus added to the cost of the expansion tank adds to the cost along with the anti-freeze at $10 per gallon etc.
Annual testing on the backflow will run $100 per year (must be done by someone certified in testing backflows and sprinklers) and that goes on forever. Add to this the cost of draining/re-mixing the anti-freeze and I wouldn't touch the smallest one for less than $250 per year total. This goes on forever.
Yes, they are cheaper but I'm opinionated and don't like them.
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- #19
ContractorDave
Mechanical
Florida! humbug... It's 8C here right now ... and we're HAPPY about it.
I'm "up here" also. The first example above is 3 sprinklers protecting a small loading bay of a grocery store, the other is 12 sprinklers at the entrance to an underground parkade. I would say that a dry system will cost significantly more initially, most certainly if you have to have a dedicated compressor. But then as SD points out there's the ongoing maintenance costs....
Personally I can't stand the stuff.
Dave
I'm "up here" also. The first example above is 3 sprinklers protecting a small loading bay of a grocery store, the other is 12 sprinklers at the entrance to an underground parkade. I would say that a dry system will cost significantly more initially, most certainly if you have to have a dedicated compressor. But then as SD points out there's the ongoing maintenance costs....
Personally I can't stand the stuff.
Dave
ChrisConley
Mechanical
My concern is the pipe corrosion we've seen in dry pipe systems. It wouldn't be an issue if they were actually dry, but I've seen pipe sections that were 80% filled with rust.
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