Device to cut (mains) based on liquid level ?

[Jethro]

As a keen home distiller, I use the Still Spirits still, which takes 4L of wash to produce 800ml of 60% alcohol (assuming you let the wash ferment as much as possible). As a rule this takes 150 minutes, but there can be a +/- 10 minute variation for reasons I have never fully fathomed. So the present way of working is to set the timer for 140 minutes, and then keep checking.

I've idly wondered how easy it would be to rig up some sort of device to cut the power, when a certain level in a jug is reached ... presumably some sort of relay. I could really go primitive and have a microswitch on a float , but wondered if there's a more elegant way ...

[The Natural Philosopher]

That's one of the easiest and float switches are standard issue.

Anorher one is a pressure switch under the jug.

[Huge]

[Adrian C]

I've used capacitive proximity switches for detecting liquid levels. Looking on eBay, they are not expensive and don't need to be actually in the drink.

[Brian Gaff]

Is it conductive?

Brian

[Adrian Brentnall]

Thanks for the 'light bulb' moment....

I used these switches _years_ ago in fork-truck automation, but that was with a metal 'target'. I never thought that they could be used with a 'liquid' target..

We have a water dosing system here on the well-water (which, untreated, is very acidic, and strips the copper from the hot-water cylinder and turns the bath-water a fetching shade of turquoise.... The dosing alkali (which is fairly corrosive) comes in 5 gallon plastic drums - but, by the time you've noticed that the drum's empty, there's a significant amount of acidic water in the system - and it's 'blue baths & earache' for a few days til it's flushed through.

Do you think that one of these ebay proximity switches could 'see' the alkali level from outside the tank and give us an early-warning that the level was dangerously low ? If so, it's well-worth () the ?16 to buy one...

Thanks Adrian

[andrew]

Many of the larger pellet stove installations use them to sense when the fuel hopper needs replenishing.

AJH

[Adrian C]

Those were probably inductive proximity sensors.

I never thought that they could be used with a

Liquids have different dielectic properties, so can be detected using capacitive methods. The higher dielectic, the more easy it is to sense over a distance. Water & Alcohol are good.

There is a table bottom of Page 55 of this. The previous two chapters of this (replace the '3') are a good read as well.

We have a water dosing system here on the well-water (which, untreated,

I last used the sensors in a laboratory for detecting the fill state of waste deionised water drum containers, the water that was used for washing out quartz crystals during manufacture and adjustment with that loverly Hydrofluoric eat-ya-bone-while-ye-scream (tm) stuff. So dunking something inside was something to be avoided, safer to hold the sensor to the outside.

I don't know the performance of the eBay ones, our ones came from Farnell at about £30 a pop.

[Bernard Peek]

Whatever you choose make sure that it's safe for use in hazardous areas with flammable liquids and gases.

[Adrian Brentnall]

Think so.... probably

Don't know about dielectric content. This stuff is very dense (more so than H2O) - Labelled Corrotex N - apparently Potassium Hydroxide

Ah yes - everybody's favourite. I use a variant of it for glass etching - more friendly but still to be treated with some caution

Too true!

I'll give eBay a try - thanks for the idea... The dosing installation has a handy float switch that disables the dosing pump and lights a led (on the dosing meter in the outside shed!) when the KOH level drops too low - but the first indication we see is blue bathwater. The idea is to have a 'getting low' sensor, to give an early warning that the stuff's about to run low, so we can refill _before_ we get the blue lagoon effect.

Thanks for the info - I'll see how it all works

Adrian

[H. Neary]

Keep it simple.

A float switch is the best bet as you would need a relay anyway even with the proximity sensor. [Actually you could drive direct, but it isn't the best solution].

The only problem with the water treatment chemical is that it is probably caustic, this would cake up the switch after a while. A clean at each change would stop this happening though.

Caustic is not flammable. Alcohol is, but there is no risk whatsoever at drinkable solutions.

Although there are plenty of crackpots out there that would go for the full monty on a shandy bottling line, alcohol has to be in a high concentration [Absinth +] and then it has to be atomised before it becomes a serious risk.

HN

[Bernard Peek]

The OP is working with hot 60% ethanol. That's definitely flammable. It's worth considering whether "intrinsic safety" is required. The idea is to limit the energy in the circuit so that even in the case of a dead short it won't cause a spark big enough to start a fire.

Personally I wouldn't consider leaving an alcohol still unattended. It strikes me as a really dumb idea.

[H. Neary]

Methinks flammability is the least of his problems.

Liver failiure might be a higher priority. A check for methanol may be advantageous also!

HN

[Bill Wright]

It would be round here.

Bill

[Peter Crosland]

As dumb as using a still without a licence?

Peter Crosland

[Andy Champ]

Won't the methanol come off first, and the late stage of the run it'll be the higher alcohols (butanol/propanol) that will be killing him?

HM C&E may be interested too...

Andy

[grimly4]

Under EU law, there's an allowance for an individual to make uummm... up to 12 Litres of distilled spirits per annum, iirc. HMC&E don't let on about this. It's possible this has been repealed or blocked by the UK govt, as my information is a decade old.