How to check your Thermometers Accuracy at Mash Temps

[bundy]

I've had lots of time to think about all things beer lately as I recover from a bout of "Man Flu"

Anyway one thing that came to me as I was coughing up half a lung one afternoon was about Calibrating Thermometers. There's been lots written about not trusting one single thermometer, even if its tested correct with Freezing Water and Boiling water at 0'C and 100'c it doesnt mean that it's right at our most important temp which is Mash temp or around 66 C. Variances of several degrees at mash temp are not uncommon so if you think you are mashing at 66 and are in fact mashing at 70, theres going to be issues. So the problem then is what can we trust? I think I might have an answer.

It got me thinking what can we use (easily and cheaply) to test at those temperatures. We know Water boils at 100 degrees so what products can we get that boil at or around Mash temps?

I did a bit of research and there's 2 products we can all get hold of relatively easily that will allow us to test our Thermometers at or around Mash temps.

Methanol and Ethanol

Ethanol is fairly common these days as many internal (Fancy) heaters use Ethanol as a fuel source. Here in Australia you can buy it from your Local Hardware in 1L containers.

Methanol is a little harder to come by (Here in Oz anyway) But you can pick it up from Hobby Shops again in 1L containers. It's often used for Model Cars and Planes. On a bigger scale it's often used on the Car racing scene if you want access to 200L drums of it!

Now both these products are flammable and they are both Alcohol based. (Not designed to drink so don't get ideas) So being Flammable they must be handled appropriately.

Anyway the main thing of interest to us HomeBrewers is their Boiling points.

Methanol has a boiling point of 66' Celsius which is just about as perfect as you can get for checking your Mash temp accuracy.

Ethanol has a slightly higher boiling point of 78' Celsius so whilst not perfect is a lot closer than boiling water, and also works well for a Mash out temp check.

So if we were to carefully bring either of these to products to the boil (insert warnings - Carefully, with no naked flames, in a well ventilated area etc etc) We can then test the temperature of our thermometers at the most important Temp to us.

So as long as you aren't Stupid

it's an inexpensive and quick way to check your thermometer accuracy, using a product readily available and costing only a few $$. Once you have tested, let the Methanol Cool, tip it back in its container and put away until you want to test again.


I'll say it again just to cover my butt, if you have a tendency to always cut yourself shaving, trip over things, hit your thumb with a hammer, fall asleep with Cigarettes in your mouth then maybe this method is not for you.

Both these products WILL ignite near open flames. So for those with Gas Cooktops it's a definite No No.

Otherwise test away ......

 

[GABBA110360]

I'm not quite sure about boiling either methanol or ethanol on a gas burner to calibrate a temperature probe
OHS might be a small issue I think
if your particular thermometer works for you then that's all good I reckon

 

[n87]

... or you could use an electric cooktop?

 

[Mardoo]

Very interesting. Good work! Now to find an electric hot plate.

 

[Black n Tan]

Sounds like a recipe for disaster to me. Boiling flammable liquids just isn't sensible, even on an electric stove top. There are plenty of other things that could ignite the vapour. We've seen a few photos from the emergency department with exploding bottles and wouldn't want to see a stream of photos from emergency of burnt faces or worse. I for one won't be dong this.

 

[GalBrew]

Sounds like a recipe for death......or at least serious burns.

 

[Ducatiboy stu]

Might be ok if you did it outside with a light breeze. If it didnt have an ignition source it would be ok.

 

[VP Brewing]

That sounds bad. Find out if there are any laboratories in the area and take it in to them. I work in a chemistry and microbiological lab that tests drinking water and waste water etc. we have thermometers that are super accurate and worth $300. All i did was put my thermometer and the work one in a water bath at 65deg and worked out mine was the same. Took ten min and I'm sure they would be happy to help.

 

[bundy]

Sounds like a recipe for disaster to me. Boiling flammable liquids just isn't sensible, even on an electric stove top. There are plenty of other things that could ignite the vapour. We've seen a few photos from the emergency department with exploding bottles and wouldn't want to see a stream of photos from emergency of burnt faces or worse. I for one won't be dong this.

Really? You are thinking a bit extreme IMO. This isn't a drug lab kit!

How do you think distillers get their product? They boil off ethanol from the water mix to end up with a more purified finished product. That's boiling Ethanol....


But hey if you don't feel safe doing it then by all means don't, but no need to go to extremes with doomsday scenarios either. Hey some people wont change a tap washer in their house, or a car tyre. Me I'm not like that.

 

[Ducatiboy stu]

Doomsday naysayers on AHB... Impossible.

 

[TSMill]

But in distilling the volatiles are fully contained and rapidly condensed, and still people find ways to blow up their home distillation operations. Doing this in an open container is asking for a Darwin award.

 

[Phoney]

Buy yourself some good laboratory grade, calibrated glass thermometers eg: http://www.livingstone.com.au/?PG=search_result&CAT=6&search=thermometer

Then compare it against your ~$30 digital at mash temperatures.

 

[Black n Tan]

Really? You are thinking a bit extreme IMO. This isn't a drug lab kit!

How do you think distillers get their product? They boil off ethanol from the water mix to end up with a more purified finished product. That's boiling Ethanol....


But hey if you don't feel safe doing it then by all means don't, but no need to go to extremes with doomsday scenarios either. Hey some people wont change a tap washer in their house, or a car tyre. Me I'm not like that.

Mate I admire the ingenuity, but on a public forum with people of different abilities and knowledge it could get dangerous. Boiling concentrated alcohol in the open is a little different to closed system distilling. The risk may be relatively low, but the consequences may be huge, so you may say doomsday and I would just say being cautious. I am sure there are plenty of safer ways to calibrate a thermometer.

 

[bundy]

Guys if you read my first post, I clearly state, no open flames, no gas cooktop and be careful. But boiling a liquid even a flammable one isn't that extreme. We are talking about bringing a small amount of liquid to boil for a few minutes to check thermometer accuracy, not about boiling litres of ethanol for hours on end.

If you look at LPG or propane gas which many of you use in your setups, it is a liquid at -40 odd degrees, as well as when it's under pressure in a vessel. Aka cylinder. So we use the atmosphere temperature to boil that into a gas and subsequently burn it for fuel. It's just it's boiling point is at a different level.

The problem with even calibrated thermometers is they are guaranteed at 0 and 100 degrees. In between can't be verified perfectly at every temperature unless you pay more money than anyone one here is willing to spend. So as mash temp is so important to our process I have suggested a way people can check it, easily and at home without involving a lab. Look at some posts on here on how many people have problems with mashes due to high temps. It's common and a recurring theme.

Some things are not entirely risk free in life, running a gas burner in your garage for several hours could be considered dangerous but as it's done regularly the risk is considered acceptable or low. Filling your car with petrol at the garage would be dangerous if you are smoking. But with all those things done with some basic safety it is considered acceptable risk.

I agree you can't cater for every person and their ability, but I would have thought most members on here who are into all grain would be a little bit smarter than your average bear.

Anyway if it's such an issue close and delete the thread. I'm was just trying to provide a solution to a known problem.

 

[GalBrew]

I wouldn't try this at home though. Maybe at work in one of the fume extraction hoods, but don't think for a second that flammable vapours can't be ignited by electronic sources. I went and bought a lab grade mercury thermometer (which itself is not risk free) to calibrate my dial thermometers and HERMS controller.

 

[Black n Tan]

Look I gave it a go and it all went pretty well until...

 

[Ducatiboy stu]

Boiling it out in the open is not going to make it explosive if you only dealing with small volumes like a litre. It only becomes explosive with the correct fuel:air ratio which out in the open with a light breeze is going to dilute it. It might catch fire, but wont become "explosive". If you did it inside your shed where there is no means to dilute the vapours then it can become explosive. The same way as a leaking gas bottle become explosive in an enclosed area.

If you have a leaking gas cylinder outside it wont become explosive. It will catch fire. If the cylinder gets hot due to it being in a fire tge pressure will make it burst and explode. But your talking 2 different scenerios.

If you take a litre of petrol in an open container and set it alight outside it wont explode, but it will burn. It will even boil the petrol in the pot, but wont explode.


Ok.....now I have ignited the fuse its time to stand back and watch an explosion.....AHB style....

 

[lael]

So if I put 30ml in my fermenter and shake it, then light it... Quick sanitiser right?

 

[wynnum1]

30 ml of Methanol is all it takes to kill do you want to have at your house and boiling is going to give you a headache from the vapor.

 

[Eagleburger]

I am glad everything was not as dangerous when I was a kid. I may not have lived.


The easiest way to achieve the original goal would be to use that evil bitch statistics. Take three or more different temp measuring devices and if they are within a degree of each other in your desired range be happy. There are statistical methods that can assist, I refer you to google.