Tank gauge and projects ....

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Probably like some others - I have water tank under fwd bunk that needs a sensor to tell me when full. That's usually me with swmbo outside with hose in filler.
Just found this little number in Maplins that surely could be adapted very cheaply to give a buzz when tank full ......

<a href="http://
<a href="http://www.maplin.co.uk/Module.aspx?ModuleNo=22564&criteria=batterys&doy=6m3" target="_blank">
http://www.maplin.co.uk/Module.aspx?ModuleNo=22564&criteria=batterys&doy=6m3[/url]

Now it got me thinking that this works with water .... but not in oil. So how to get similar buzz when tank full ? Now my mind then conjured up following :

Clear plastic rigid tube open both ends. Have small button magnet on a small float in side tube. Close bottom of tube but drill small holes to let diesel in ... Top of tube has reed switch positioned across it and at level that you want the buzz to go. leads from switch to low power dc supply, on-off switch and piezo buzzer ....
Set plastic tube vertically in tank ... you could even make it portable if you like ... so only stick in tank when filling ??

Any one see a flaw or improvement that can be made - but keeping it cheap and DIY ... I am aware of Tek-Tanks and others who do proper gauges etc.

It sort of follows on from matey who made up Battery Volt monitors from multi-meter and switch. Great stuff.
 
Use the tube with an switch from a washing machine on the top, sealed end.
As the fuel fills the tube, increased air pressure will activate the switch at a pre-determined point. The advantage is there's no contact between the fuel and switch.
 
wash machine bit ....

mmmmmmm interesting - never thought of that ...

I even wondered if a second reed could be mounted lower to give a low-level warning.

I have a sender lid bolted into the tank ... but no gubbins fitted or gauge. The tank looks like a small truck or other vehicle tank - so only he knows what unit to fit etc. So my thoughts to bodge up a buzzer ....
 
Re: wash machine bit ....

Nigel

Our Etap 28i had a fuel gauge which was just a clear tube, in th eheads (fuel tank behind bulkhead), roughly calibrated, 'full', '3/4', '1/2' etc. It always was a little behind the actual contents of the tank so had to be cautious when we go to near full.
 
Clear tube ...

I know the type you mean ... and you can actually put the top of tube back to the top of tank to close it off.

I'm looking for a way to know when to stop the fuel-hose when standing holding the pistol on deck. Most time I have to ask the fuel dock guy to do the filling while I'm inside boat monitoring level. With a buzzer system - I have audible warning ....
 
Re: Clear tube ...

I find with mine that simply listening gives the feedback on when its full.... the note changes qute considerably as the tank fills, and especially as it reaches the fill pipe..... mind you, the fuel tank is only 8 gallons, so I can fill it fairly slowly... wouldn't want to do that for a 40 Gallon tank!
 
Mines under the fore bunk ...

and a solid steel job. Ex truck.

The filler pipe is large bore plastic and sound really is affected by the filler pipe .. I tried it - but couldn't do it with confidence. The nature of the fill as well needs a settling time of some seconds near top of tank to get that last few litres in ... total about 70 litres ...

Methinks I may risk taking of the sender plate and see whats under there ....... maybe if I find a float mechanism - I can use that to set off a buzzer >>>>>>??????

The water tank is sorted with that Maplins bit of kit - once I get back to UK ...
 
Re: wash machine bit ....

Have found that the red in the diesel stains the clear tube to the point of not being able to see the fuel level.
Note that on an insurance survey we were warned to have a shut off or pull to read valve on the bottom of the sight tube.
 
Re: wash machine bit ....

Yes this is true, it was getting dificult to read, the bottom of the tube did have a tap.
 
Re: Or this little baby .....

We've got a vetus tank and have just put in a Faria sender and Fuel Level Gauge - there was a blanking plate on the top of the tank with 5 bolt holes - the Faria sender sloted straight in. We've wired up the Fuel Gauge (as per instructions) so it only reads when the ignition switch is on, but a constant 12v supply would do (u'd need to switch it off somwhere...

The sender has a float on a rod with 2 wires out the top so I guess some sort of resistance device (don't really care for our instalation cos it works!)
 
Not my idea, but two circuits are given in the back of Wing's 'Boatowners Wiring Manual' both using half a dozen cheap components from Maplin including a 741 op amp - probably cost about a quid each to make. Each uses a 'probe' made of a bit of old coax cable with the insulation stripped back from the outer screen.

One goes off when the liquid bridges the conductor and screen, the other goes off when the liquid falls and the bridging breaks.

You can add extra sounders, LEDs, relays etc as you want to.

Happy to scan the pages if you're interested
 
very interested in any ideas

Ideas that solve this easily and without breaking the bank ...
 
So spreadsheet in hand ...

With part numbers / pricing / description ....

I shall have a date with maplins next time back end of this month .... then its a couple of days with soldering iron etc.
 
Re: So spreadsheet in hand ...

Sorry Nigel - scanner probs. These are prolly big but rough...
I make it about 54p for the op amp from maplin, 10p each for the resistors
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Nigel,
how about this http://www.hendersons.co.uk/boattank/index.html??

Not as cheap as you want, but not at a break the bank level - and not from a boating company!

I am going to fit one in my boat.

I have asked them if one could be modified to measure fuel - I would imagine that it would be whether the sensor be fuel safe (ie, doesn't dissolve).

You should have some knowledge of these type of sensors in your job. We had some in use on the box-boats I was on, to measure steam pressure (steam ship and turbines), and bilge levels.
 
Are you sure it doesn't work in oil? Do you mean oil or diesel?

I have a sensor from RS that works on a total internal reflection priciple. I am sure it will sense a rising level of diesel but not so sure that it will clean itself as the level drops
 
Many thanks to all ....

I now have scans of projects - which will be made up to do various jobs I have ... (thanks Raedweld) ... I now have ideas for full and near empty water tank ....

If the Maplins overflow alarm that I have bought works in diesel - then I'm laughing !!

Many thanks to all ......
 
Electrical Fuel Gauge

I have found a manufacturer who will make a fuel gauge for boats with bottom fuel take-off - and who do not want to remove the tank and cut a hole in the top for a top sender.

To begin with, it is not cheap, £75 +VAT +delivery....but, take into consideration the draining of the tank, removing it and getting a hole cut in the top, either a flange made or a boss welded in, buying a top mounted sensor and gauge, and the cost is not so great.

This gauge (and let me say, I have nothing to do with the company which is somewhere upcountry) is for tanks with bottom fuel take-offs or bottom drain cocks.

My Duo has a tank that would take an expert to remove, and I cannot get to the top of the tank to do any work to fit a top sensor. What I am getting made for myself, will fit into either the bottom fuel line, or as I an doing, into the drain cock - mine is ¼” bsp.

The sensor is a pressure transmitter, that measures the "weight" of the fuel in the tank. I don't know the specifics, but would guess that it is a milli-amp output to a gauge. If it is the same set-up as I had when I was in the MN on containerships, you set zero with the tank empty (or drain cock off and no fuel in the line) and then set full with the tank full.

Please note, if the boat is used on inland waterways this method will not comply with the current regulations.

If anyone is interested, let me know, and maybe we could get the cost down by having a number made at the same time.
 
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