Water Sensors (recommendation request)

[Noway2]

I have been looking at literature for on/off water detection sensors and I am looking for some opinions regarding which brands, or even products are decent. From looking through old eng-tips posts, I am finding (old - and yes I was around ET for the original depth of water sensing thread) references to brands that I have been looking at, like Water Alert and I was wondering if anyone has experience with them and if so, would you recommend them?

The application is to put 4 or so of them around a room and monitor them for signs that the room is flooding with water. The sensors would be powered and monitored by the plant DCS controller. Ideally the product would be something installable by maintenance type people, not an OEM sensor for inclusion in a product which seems to be how Gems and similar sensors are geared.

I am also looking for a water level sensor, which doesn't need to be terribly accurate (1/4" to 1/2" for example), that could mount on the wall and could be read by the DCS to measure the water depth in the advent of a flood.

The goal is that if 3 of the 4 water sensors trip or the level sensor says that the water depth is about 6" that we will turn on a large sump pump to remove the water.

I was wondering if anyone has a product that they would recommend for this purpose?

 

[KiwiMace]

Water detection, try Liebert spot or cable sensors. The data center industry has everything from spot sensors to cable type with location detection.

 

[IRstuff]

Seems a bit complicated. Why not just have a single sensor over the sump pump? If there's no water at the sump pump, then there's nothing to do, while if there is, presumably, you want to pump it out.

TTFN

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[Noway2]

@KiwiMace, Liebert is a good suggestion, thank you. I can see why they would offer this sort of thing, but it wouldn't have crossed my mind.

@IRStuff, maybe a little complicated. The monitoring is to get an alarm out to whomever is on call. It is in the basement of a water chiller (A/C) plant and a city water supply line had a flange joint fail and flooded the building a few weeks ago. The pumps, which are up on pedestals survived, but it wiped out all the VFDs to the tune of $300K. We did get a 'sump' alarm and one failure on top of another with some bad practices and planning made the situation worse. So, the boss is being a little gun shy and willing to put a couple $K into a slightly more robust setup. There already is a couple of small sump pumps, but they couldn't keep up. Were going to put in one with about a 40 HP pump that should handle a 6" line breaking (again).

The plan is for the the sump to have a float switch in the basin to turn it off and the water sensors / level sensor turn it on. At 3" of water we want to send out an alarm indicating that the place has a "real" problem and at 6" send out another "it is getting worse" alarm. The building should handle several inches of water and survive, just not the almost 3 feet that it got before it got shut off.

 

[waross]

How about a bubbler system?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

Do you really want to or have to allow 6" of water to build up before knowing about it? If not, Balluff makes a great little capacitive simple leak detector. it has an integral cable and a sealed case with a frame that holds is a few mm off the floor. If any moisture gets between it and the floor, the contact closes. Wire them back to a simple smart relay and set up basic voting logic (must be any 3 out of 4) and you're done. We use them all the time in data centers and semiconductor TGO monitoring situations. Capacitive is VERY reliable and not prone to false triggering once set up properly.


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[danw2]

Winland makes several models. My clients use the Water Bug model WB-200, dc powered.

http://www.winland.com/waterbugalert.html

 

[rbulsara]

Along the same line what kiwimace suggested, check out Perm-Alert.

http://permalert.com/

. This is very popular for leak detection in data centers and electrical rooms. There are others too. It has its own control panel and also lets you know how far down the cable the leak is.

Rafiq Bulsara

http://www.srengineersct.com

 

[Noway2]

Wow, thank you to everybody for the responses. I will check out the different makes and models of the leak detectors. This is exactly what I was looking for.

@Waross, is something like this what you meant by a bubbler system? Looks like an interesting concept that might be better than a radar approach (which is what we use for cooling tower basins). How well would that work to measure the water level in a room that is normally at zero?

By the way, it is good to see that the old crowd is still here and active! It has been a few, several actually, months since I have been around eng-tips.

 

[danw2]

If you're actually willing to let 6 inches of water accumulate before you alarm, it works fine to mount a waterbug (or one of the other sensors) 6" up the wall.

That happened at one greenfield plant, in the basement of all places. The intention was to have it installed on the floor, but nobody caught the wrong installation until there the alarm came from 6" of water from a broken hose.

 

[Noway2]

Haha, that's actually kind of funny, though I am sure it wasn't so amusing at the time.

I am thinking that one of the sensor lines that goes along with some of the detectors might make a good wall mount device. The desire to know the water depth is to get an idea of the severity of the situation. As I mentioned in my initial post, we are going to install a sump pump that will handle the breakage of a 6" line. There are some bigger (24" and 36") lines, but I don't think we could put a sump in big enough to handle that.

Normally, with this type of cement lined ductile iron, we use flanges that are threaded onto the pipe since you can't weld it. In this particular case, somehow during construction several years ago, one that only had set screws, it wasn't even a restraint with teeth, got used and eventually worked its way loose. Hopefully this was a unique event.

 

[danw2]

The capacitance units in plastic boxes aren't really designed for submersion.

There's also the venerable conductivity switch whose electrodes don't care if they are submerged for exactly that. Just mount the head and electronics above where the expected high water line.

To establish the switch points, you cut two of the electrodes off at the low level trip point and cut the 3rd electrode off at the high level, based on the elevation of the unit when installed.

 

[ozmosis]

One from Siemens to look at:

http://www.automation.siemens.com/w1/automation-technology-the-probe-18722.htm

"The Probe" is one that come over from milltronics when they bought the company. Very simply and easy to use from my memory.

 

[Noway2]

Thank you both for the links. I will check them out.

 

[danw2]

The Probe is a Siemens (formerly Milltronics) 3rd generation device. Its 5th generation replacement is the Probe LU. For the $100 premium, it's a better box.

http://www.automation.siemens.com/w1/automation-technology-sitrans-probe-lu-18721.htm

Be aware of an ultrasonics installation consideration. I know of a number of Probe style ultrasonic transmitters used in municipal manholes. The problem was that the ultrasonic transmitter is mounted at some elevation, in this case about 5 feet up from the floor, with a nice, convenient empty spot underneath it. The empty spot was a great place for a bucket of tools, a pipe threader, boxes of supplies, whatever, when people were working in the area.

They ended up having to install railings around the area to keep down the nuisance alarms from workers using the open space to temporarily store stuff. Ultrasonics works great, but its echo bounces off 'stuff' just as well as it bounces off water.