Water Level Sensors

[benno1973]

Just wondering how people with automated breweries are able to sense water levels? I understand it can be done using a capacitive approach, where the volume of water affects the conduction between two probes? Is this right?

I'd be interested in putting something together that can measure volume in my HLT and boil kettle using probes or the like. And yes, I can (and do) use a graduated measuring stick, but it's another step I'd like to take towards automating parts of my brewery. Ideally I'd like to be able to read the results into a computer via RS232 or something, but not sure what's involved with that

I have no background in electronics, and don't even understand the stuff, but I did manage to put together a tight arse stir plate, so simple things I can manage. And I'd like to learn, so if it's a simple project, I'd love to give it a go. I have a background in IT, but more in software development, which means I know nothing about hardware or the electronics side. I'd go nowhere near mains power, but small scale stuff (i.e. as long as I can't kill myself) I'd love to play around with.

I notice that Jaycar are selling this device which measures water levels in water tanks - not sure if this sort of thing might be appropriate as a starting point, but I'd like to be able to get a volume readout rather than just a high/med/low 'indicator' so I guess some tweaking would be required. But is that sort of thing possible?

Anyway, any suggestions welcome, whether it's links to other websites or whatever. I've had a look over Zizzle's brewbot thread, but I can't see where it mentions how the level probes are hooked up. I've googled it, but can't find any simple project on how to put something like this together. Maybe it's not simple, and that's fine too, but I thought I'd ask the question...

 

[Offline]

You can get ultra sonic level sensors, Im not sure that they would work with boiling liquids

Another option would be scales; one litre of water weighs one kilogram

 

[jonocarroll]

Another option would be scales; one litre of water weighs one kilogram

Depending on how precise you want to get.

Scales were my first thought too. Best way would be to just calibrate it properly - measure it empty, call that zero, add a known quantity of water and measure, repeat until full. Then do the same again when it's at temperature and see if it's different. Sometimes the simplest solutions are the best.

 

[Supra-Jim]

If you're looking at automation, you're probably going to trasferring you liquid with a pump. Why not loose the level sensors and install a flow meter into the pipework?

:icon_cheers: SJ

 

[benno1973]

If you're looking at automation, you're probably going to trasferring you liquid with a pump. Why not loose the level sensors and install a flow meter into the pipework?

:icon_cheers: SJ

Actually, it's currently a 3-tier gravity fed system. Not that I have anything against pumps, I just what currently works and I'm happy with it. A flow meter is an interesting idea, but I assume they're not cheap?

I thought about weight, but it's difficult to measure the weight of a ~50kg boil kettle with a flame underneath.

 

[Supra-Jim]

A level sensor that can handle boiling bubbling liquid and measure the level as it changes in the tank (i.e. opposed to a switch that indicates once a particular/fixed level is reached) will not be cheap either. You would really need something that sit in the lid of your HLT and and a probe or sensor that descends down into your water, all the way. This will not be cheap.

Nothing wrong with a gravity fed system, was just making an assumption about your move towards automation.

:icon_cheers: SJ

 

[newguy]

Flow meters (the ones I've been able to find) start at about $300-400 US. Omega Engineering have a wide variety. Load Star Sensors have a nice range of mass sensors and various hookup arrangements which allow you to use them in a hanging arrangement. Load Star Sensors. I'm not sure how much $ the mass sensors are worth.

 

[jonocarroll]

I thought about weight, but it's difficult to measure the weight of a ~50kg boil kettle with a flame underneath.

My thoughts were to hang the HLT from the ceiling/with a support of some kind and connect something like this in-line. It's even got RS232 output.

 

[kirem]

http://www.parallax.com/Store/Sensors/Obje...e%2cProductName

That could be the basis for a homebrew ultrasonic level detction and measurement.

they also have pressure sensors, I know they used to have a pressure sensors capable of more than 1.6lbs.

 

[benno1973]

My thoughts were to hang the HLT from the ceiling/with a support of some kind and connect something like this in-line. It's even got RS232 output.

Nice one! I brew outside, so I'd need an engine lifty thing (I'm not a mechanic either! ) but great idea. Unfortunately it's $700, so a bit pricey for me...

 

[mika]

Weighing everything with the burner included in the weight measurement would be the best way to go. They use Ultrasonic level sensors here, big ticket items, but some process engineers are not that keen on them, due to the moving surface (from other flows feeding in) affecting the accuracy of the reading. Differential pressure sensors seem to be the preferred option, though in a 30m3 tank, there's a fair bit of differential pressure from top to bottom. In a 50L pot, not so much. And I'm not sure what sort of temp they can withstand. If you're just wanting to know whether the pot is full or empty a simple float level switch is hard to beat.
Othwerwise maybe look at a float and guide within the vessel (I couldn't get it to work, though I didn't invest a lot of time) so that the sensor equipment can be kept away from the hot liquid and the such and use a resistive scale to measure volume. Much the way a fuel tank guage works in a car. Proximity sensors are fairly cheap as well, so perhaps a controller could be configured to 'count' tags on the float guide as the level changed.

 

[newguy]

The parallax PING ultrasonic sensor probably wouldn't work long in a high humidity/high temp environment. I looked into ultrasonic and ruled it out because of the need for environmentally "hardened" models.

What about a pressure sensor? Imagine a tube with a pressure sensor at the top. The tube runs down the side of your vessel and stops just short of the bottom. As water fills the vessel, the air pressure in the tube climbs. Read the pressure and bingo, you have your liquid level. Pressure sensors come in all sorts of pressure ranges and are quite cheap.

 

[benno1973]

What about a pressure sensor? Imagine a tube with a pressure sensor at the top. The tube runs down the side of your vessel and stops just short of the bottom. As water fills the vessel, the air pressure in the tube climbs. Read the pressure and bingo, you have your liquid level. Pressure sensors come in all sorts of pressure ranges and are quite cheap.

Great idea. Would that work over the range of temperatures from ambient to boiling?

 

[newguy]

Great idea. Would that work over the range of temperatures from ambient to boiling?

It should. Pressure transducers are commonly constructed from SS. If the sensor isn't capable of handling steam, just extend the tube away from the vessel. That would allow the steam within the tube to cool without affecting the pressure reading.

I just had a quick look through my Digi-Key catalog and most pressure sensors are rated for at least 85C. Good enough for HLT and mash tuns.....also good enough for a kettle so long as the sensor is far enough away.

 

[kirem]

The parallax PING ultrasonic sensor probably wouldn't work long in a high humidity/high temp environment. I looked into ultrasonic and ruled it out because of the need for environmentally "hardened" models.

hence in my post I said the BASIS for a homebrewed solution.

I like your idea of an air pressure sensor. The seal to create the pressures could prove difficult to maintain and would need to be environmentally hardened

 

[jonocarroll]

What about a pressure sensor? Imagine a tube with a pressure sensor at the top. The tube runs down the side of your vessel and stops just short of the bottom. As water fills the vessel, the air pressure in the tube climbs. Read the pressure and bingo, you have your liquid level. Pressure sensors come in all sorts of pressure ranges and are quite cheap.

Along the same lines - what about instead of sealing the tube for pressure, have a float inside attached to a (not-too-heavy) pole coming out the top... you could put a slide-wire-potentiometer at the top, and measure the float level by proxy like that. Just a thought.

 

[newguy]

I just ran some numbers. Unless there is something wrong with my calca, the pressure in the tube is too small to measure with a cheap pressure sensor for rather normal sized kettles/HLTs (approx 50 - 100cm deep). Which of course explains why I haven't seen a liquid level gauge like this before.... <_<

However if you put a piece of styrofoam (the float) at the bottom of the tank connected to the plunger on a syringe-like deal then you could kind of amplify the pressure and be able to use a standard pressure sensor to measure liquid level. The float doesn't have to be styrofoam - it could be an air filled copper or SS tube.

 

[technocat]

Kaizer Sose: If you are just a little electronic savvy I can show you a method of water level detection you can make yourself just using two transistors, a SCR to drive a relay with its inherent diode. You would need to make up a probe using two wires in a thin tube sealed at one end with epoxy, and fix this to the top of whatever vessel you are filling. HLT maybe, all for the fraction of the cost of a commercial job. You would need a low voltage 12VDC supply probably from a plug pack capable of delivering up to half an amp.

 

[benno1973]

However if you put a piece of styrofoam (the float) at the bottom of the tank connected to the plunger on a syringe-like deal then you could kind of amplify the pressure and be able to use a standard pressure sensor to measure liquid level. The float doesn't have to be styrofoam - it could be an air filled copper or SS tube.

Yeh, that's an option. I had a look on the Jaycar site, and found this, which (as you say) has temp compensation up to 85C. This was the kind of thing you were thinking of? And I guess you just make the tube long enough so that the float can rise from the bottom to the top of the vessel and provide a measurable pressure differential?

Kaizer Sose: If you are just a little electronic savvy I can show you a method of water level detection you can make yourself just using two transistors, a SCR to drive a relay with its inherent diode. You would need to make up a probe using two wires in a thin tube sealed at one end with epoxy, and fix this to the top of whatever vessel you are filling. HLT maybe, all for the fraction of the cost of a commercial job. You would need a low voltage 12VDC supply probably from a plug pack capable of delivering up to half an amp.

Beernut - this is exactly what I'm after. I am almost an electronic illiterate, but I'd be interested in learning how to do this. If you even had a circuit diagram or something, I'd be happy to go away and do a bit of research to see if I could work it out. Any help appreciated!

 

[roger mellie]

Just wondering how people with automated breweries are able to sense water levels? I understand it can be done using a capacitive approach, where the volume of water affects the conduction between two probes? Is this right?

I'd be interested in putting something together that can measure volume in my HLT and boil kettle using probes or the like. And yes, I can (and do) use a graduated measuring stick, but it's another step I'd like to take towards automating parts of my brewery. Ideally I'd like to be able to read the results into a computer via RS232 or something, but not sure what's involved with that

I have no background in electronics, and don't even understand the stuff, but I did manage to put together a tight arse stir plate, so simple things I can manage. And I'd like to learn, so if it's a simple project, I'd love to give it a go. I have a background in IT, but more in software development, which means I know nothing about hardware or the electronics side. I'd go nowhere near mains power, but small scale stuff (i.e. as long as I can't kill myself) I'd love to play around with.

I notice that Jaycar are selling this device which measures water levels in water tanks - not sure if this sort of thing might be appropriate as a starting point, but I'd like to be able to get a volume readout rather than just a high/med/low 'indicator' so I guess some tweaking would be required. But is that sort of thing possible?

Anyway, any suggestions welcome, whether it's links to other websites or whatever. I've had a look over Zizzle's brewbot thread, but I can't see where it mentions how the level probes are hooked up. I've googled it, but can't find any simple project on how to put something like this together. Maybe it's not simple, and that's fine too, but I thought I'd ask the question...

You wont find a cheap sensor - liquid level measurement is done in numerous ways - all quite expensive:

Differential Pressure - Transmitter would cost say 2K - accuracy comes into play when the difference is small
Ultrasonics/Guided Wave Radar - horrendously expensive - take a lot of setting up - dont like turgid surfaces - or steam.
Metal Tape - not cheap either - not suited to miniaturization
Float methods (where a metal float goes up an down a sight tube and inductive sensors detect the level) - you could make your own but inductive sensors arent cheap

I would discount flow measuring level and this is usually not accurate enough.

By far the simplest and cheapest way of simple (non adjustable) liquid measurement is

http://uk.rs-online.com/web/search/searchB...t&R=0845976 they are available in Aus - I think mine cost me 23.00

I use these on a couple of other water tank automation projects I have around here (low level cutouts) - they are cheap - can handle boiling liquids.

I always thought that if I ever got round to building a brewery worthy of automating that I would use these - the automation side of level control in a 50L brewery is usually to fill up a vessel to a pre determined level then heat it. The analog reading of how much in the tank is immaterial - repeatability is paramount.

Thats my 2c anyway

RM