Water tank level indicator.

I have some fancy water level indicators by Centroid. The Port has failed twice now and they are not cheap.

I have wondered about a washing machine water level switch. I know it will not give me a variation in voltage or work the guage --but--

I could rig it up to alarm when water level gets low ( switch on ) and to alarm when full (switches off).

I have never seen a washing machine water level sw but I am assuming that it does not need a supply and will therefore switch any voltage

A bit of juggling with normally open or normally closed relays should get the required result switching lights N stuff. Not a perfect world but better than guessing.

Stbd side is good and gives no trouble. Centroid unable to supply me with one as they are not able to post small items.

Any suggestions.

 

Use a fuel tank sending unit. There's no voltage involved, it just senses a percentage of ground. If you pull off the bezel ring on a fuel gauge, you can print a new face or you could just put "Water" on it and close it up again. They come with adjustable float arms for different depth tanks, so you're go to go.

Then again a graduated stick is fairly fool proof.

 

Frosty,

I have used washing machine switches for a sanitation system I was involved in manufacturing, they are unbelievably reliable.

They are pressure sensitive switches, we used German ones, but forget the brand right now.

We used a piece of PVC pipe, put a plastic reducer into the top using hot glue sticks and connected the reducer to a piece of hose the appropriate diameter to suit the pressure switch, about 1/4".

In operation you sink the tube into the water and when the preset pressure is reached, the pneumatic switch operates. There was about 2 inches variable from entering the water to switching on/off.

These switches are tested to over 100,000 cycles....if you were that lazy and did not fix ya boat then you would deserve to sink.

I have used then since as both bilge pums switches and high level alarms, excellent.

When we used then in poo tanks, my design had a flaw, the poo could eventually get up the tube and could block the air operation, the senders had to be removed and cleaned to solve the problem, but very rare anyhow, in fact i know of only three cases where thus ever occurred in hundreds sold.

Never had any switch failures. Another good thing was the length of the tube (PVC), could be altered without much research to find the switch point, the air basically in compression did not matter much if they were 6 inches long or two feet long, they still operated in about 2 to 3 inches.

Because the switch is never near sea water, the switch never gets wet, as is usual for most float switches, so they last indefinately.

I can find out brands etc if you really need me to, but I am in China again for a few more weeks mate, then back home to Brisbane.

 

PAR,

Using "bought " ones, the Wema senders are very good.

 

If you want to go with an absolutely reliable level alarm, have two supply lines from the tank, one higher than the other. Set up a simple diverter valve and your alarm is, "Hey! there's no water!" Then you remember you installed two lines and there's still a few gallons left. Flip the valve and now you can live for a few more days.

 

I first read this alan, and though , crap, then it became more obvious how simply really this is....you know, I am a believer!

Not exactly a sender indicator, but it certainly is a good reserve, sort of like on my bikes.....not that I would ever run out of fuel, oh no.

 

A fuel tank sender unit?---in water? It would drop apart in months.

The ones that I used were just two wires basically and the amount of leakage from one to the other was calculable and dependant on water level.

It has two adjustable potentiometers fro high and low. There can be much in it circuitry wise.

 

Frosty, the Wema type of sensor has a float on a tube slide, vertical, you buy the one that suits the tank depth, they are super reliable, yeah, the old VDO, sliding potentiometer type are crap, with a capitol C.

 

Modern fuel tank senders have a stainless steel wire, a plastic body and a ceramic variable resistor, so no chance of corrosion. Unfortunately most are part of a fuel pump and not available separately.....

The washing machine membrane switches and cheap and long living, but not very accurate.

A 3rd option is a float switch, molded from reinforced pvc, with a small magnet in the float and a reed contact in the body. Single 1/2"hole mounting with a rubber gasket, 3 ft or more wiring molded in. A low cost industrial product, used in numerous applications like agriculture, chemical industry, swimming pool filter units etc.

 

I second CDK. Magnetically operated reed switches are extremely reliable, if you don't draw too much current through them, and very cheap (digikey.com carries them). Rare earth magnets to operate them are also cheap (try http://www.kjmagnetics.com) and available gold plated for corrosion resistance.

You can make an excellent syntactic foam for a float out of glass microspheres mixed into epoxy, and brew your own to order. Guaranteed to last longer than any of us will.

BillyDoc

 

Sound your tanks daily - amazing how acurate a bit of string on a nut is, the only thing that can go wrong is the string breaks, tie on a new nut and your back in business!! the wet bit of string gives you how much you have, the dry bit tells you how empty the tank is, when its more dry than wet - panic.........so simple even you could not go wrong..........go wrong......go wron........

 

Walrus,-- it is a cat weight is critical ,I dont go out with more that I need.

The tanks are forward in bedrooms , I will have to lift up the carpet and get access to the tank and drop nuts on string in????

The tanks are 400 each so I would be doing this daily.

Any more ideas?

CDK can you ellaborate on your 3rd option, it sounds an interesting project.

Any one know how to repair the centroid sender like bash out the epoxy sealer.

 

Gas tanks on the older tail draggers were in fromt of the pilot and had a piece of round steel stabbed into a cork and stuck up through a enlarged hole and had 4 marks---full--3/4 full--1/2 full--1/4 full. you had to fly level to get a correct reading. 400 hours and I never ran out of gas. Might not have been cork, but it worked like a charm. Stan (1958-1960) Never heard of one being replaced. I think they call it KISS.

 

What do you call does glass tubes that run on outside of tank?

 

Level indicators (sight glasses). Not a good type if the water tanks are located below the sole, but dirt cheap and absolutely reliable..