Water storage tank level sensing

[BruceM]

Before I go and reinvent the wheel, I wonder if anyone could suggest a water level sensor/switch system for 2000 gallon water storage tank. (Off grid, no AC stuff except the pump control relay).  I've got to have a high level switch/signal, a low level switch/signal and I'd like some sort of remote level indicator (accuracy not required).

I'm thinking of using a pressure transducer and my own circuitry to control the pump relay, with an analog signal for a remote needle type indicator.

Any suggestions?
Bruce M

[rleonard]

Lots of options.  Here is a place to start.

http://www.omega.com/green/flow-level.html

Bob

[GuyFawkes]

Before I go and reinvent the wheel, I wonder if anyone could suggest a water level sensor/switch system for 2000 gallon water storage tank. (Off grid, no AC stuff except the pump control relay).  I've got to have a high level switch/signal, a low level switch/signal and I'd like some sort of remote level indicator (accuracy not required).

I'm thinking of using a pressure transducer and my own circuitry to control the pump relay, with an analog signal for a remote needle type indicator.

Any suggestions?
Bruce M

easy done, only three questions need answering first

1/ range from "you" to tank

2/ elevation from "you" to tank

3/ purely visual indication for "you", or automatic switch control too?

("you" = place where readings are going to be taken)

[BruceM]

Thanks Bob, but Omega's prices are not in my budget. I'll roll my own rather than spend $600. on a submersible pressure transducer.  I can get a suitable pressure range transducer for $8. at Digikey.

Guy-  The pump relay (and power management PICaxe chip in the future) are located in a pump house just a few feet from the 9' tall water storage tank. No elevation change.  I need water level info there, but also would like to remote the water level info down to my shop building in the valley, 26 feet below in elevation, and 260 feet away. I can handle most analog and digital circuit design myself, but like to use off the shelf hardware when practical.

Best Wishes,
Bruce

[listeroidsusa]

Since water weighs .433 lbs per ft of head I would think you could rework a simple pressure switch to get a cut-in and cut-out setting. A washing machine water level diaphram type control could probably be reworked, or at least the principles employed. A common well pump switch has both a range setting and a cut-out setting. Perhaps playing with some weaker springs might be in order?

Mu .02 worth,
Mike

[GuyFawkes]

Thanks Bob, but Omega's prices are not in my budget. I'll roll my own rather than spend $600. on a submersible pressure transducer.  I can get a suitable pressure range transducer for $8. at Digikey.

Guy-  The pump relay (and power management PICaxe chip in the future) are located in a pump house just a few feet from the 9' tall water storage tank. No elevation change.  I need water level info there, but also would like to remote the water level info down to my shop building in the valley, 26 feet below in elevation, and 260 feet away. I can handle most analog and digital circuit design myself, but like to use off the shelf hardware when practical.

Best Wishes,
Bruce

simple sight tube can't be beat from 9 feet, except mebbe by old lister stle fuel level



float and bob weight at opposite ends of a chain

for 26 foot below, you can still use a sight gauge, just closed top, and calibrate the gas compression manually one time

[BruceM]

Thanks Guy, for the good ideas!  I could put an open sight tube inside the pump house off the tank suction line, where it wouldn't freeze.  It would be affected a bit when the boost pump is on, but perhaps not too badly.  I could also use the same trick I did on my oil level sight tube on the Listeroid- put a floating capsule (HDPE tubing with closed melted ends) with a magnet in it inside the sight tube, and then sence my high and low levels with magnetic reed switches strapped to the pipe.

Down at the shop I like the closed sight tube (there is a gravity feed only line direct from the tank for the garden and trees that goes there), but I think the trapped air will gradually get absorbed by the water.  I'd have to have a means of easily draining the line to restore accuracy a couple times a year.  (Which seems reasonable.)

Thanks again,
Bruce M

[Tom]

One way to do what you want is with multiple float switches. My system consists of a 1500 gal collection tank gravity fed from the spring with a pump and a low level float switch. This pumps to 2x3000 gallon upper tanks that I set up with a high level float switch. If you want to detect level in the tank just use as many float switches as levels you want to detect. 3 switches for high, medium and low would be easy to do, be very reliable and cost you about $75.00. Or if you wanted to be fancy the switches I used have a 3 way switch so you could indicate 2 levels with each float if you got fancy.

Or another way to do it is the way they do in RV fresh water tanks. On these there is just a brass screw through the tank and I believe it works by measuring a small current flow through the water. I have not found these to be real reliable though.

[GuyFawkes]

Down at the shop I like the closed sight tube (there is a gravity feed only line direct from the tank for the garden and trees that goes there), but I think the trapped air will gradually get absorbed by the water.  I'd have to have a means of easily draining the line to restore accuracy a couple times a year.  (Which seems reasonable.)

Thanks again,
Bruce M

bicycle valve on the top and blow in once a week.

[Dail R H]

   At last,something I know at least a little about. At one of the boiler operations where I worked we had a chain-float- weight system. Pins through the links in the chain activated or cut off the well pump. Guy's chain- bobweight thingy. We used a painted "zone" on the side of the tank with the weight to tell if level was ok.If you have the pump on a pressure switch already,a stock tank float should work to keep the tank full.A flag on a lever would indicate level from a distance.

[bitsnpieces1]

....
  I could also use the same trick I did on my oil level sight tube on the Listeroid- put a floating capsule (HDPE tubing with closed melted ends) with a magnet in it inside the sight tube, and then sence my high and low levels with magnetic reed switches strapped to the pipe.

....
Thanks again,
Bruce M

  Youv'e hit on a level gauge used in a lot of water treatment plants.  A tube up the side of the tank with a floating magnet that will activate a reed switch.  You can place a reed switch at every point you want a reading, say every 6 inches.  Each level can be used to activate an adjustable level indicator/controller.  Run wire from each reed switch to LEDs in a column where you want to be able to see it.   Doing programming work should be a snap.
 The strain gauge detecting the water level is also a widely used setup, just calculate the weight of the water in the column directly over the sensor.  The float/chain/pointer is used a lot in tanks that don't have to be sealed.  The float/chain/on-off switch is used an awful lot is small lift stations for wastewater to start and run the pumps.  Everybody has hit on ssolutions used in almost any water plant.  If you have one somewhere near go check 'em out for ideas.  Guys there should be really helpful. 

[Doug]

Hey Bruce:

I have a surplus Miltronics Probe, NOS ( although I have wired it up to play with from time to time ). This is Ultrasonic level detection 24 VDC 4-20mA output with a single alarm contact.

Contact me off list if your intersted.

Doug

[BruceM]

Thanks for the generous offer, Doug. 
Bruce M

[Doug]

No Wuckas Bruce:

The only level it measures is the dust collecting on the gizmo bench of unfinished toys....

Its probably time for me to have an Ebay auction.

Doug