Cheap pyrometer / thermocouple from eBay?

[tomhumf]

I'm looking for a pyrometer for my adventures into gas firing. All the ones available from UK sellers are around £250 including tax and delivery. I've seen some cheapy ones on eBay - I guess I can't post a link but I'm sure you could find it. There are around $65 USD Inc delivery. They are k type, rated up to 1300 Celsius apparently. 

I just wondered if anyone has used ones like these? I would be using cones too, especially for final firing temp. Really I'm just looking for something to check if the kiln is climbing in temp. 

Thanks! 

[Mark C.]

The best ones are Flukes-they are bullet proof

I have about 4-5 at any given time . 

The model I like is a Fluke 51 K/J Thermometer

This is single kiln use unit(I also have one with two leads for two kilns at once)

These are on E-bay all the time.60$ is to much to pay -just wait and find one that is going for less and put the money into shipping it to the UK.

Any type K thermocouple will work with this unit.

I just picked up one for under 35$-You will need the two prongs lead (its always a yellow plug)and the 6 foot of wire. Often they come with this or you can but it extra  on eBay as well.These handle up to 2400 degrees(you do the conversion to Cel)

I suggest buying one of these over any cheap knock offs-these are older flukes but once where top of the line. They take a 9volt battery and you get to it by the 4 screws on the back.That battery will last years.

I use this eon my 3 gas kilns and an electric.Also any kiln I'm working with or on as I travel. I have turned lots of potters onto this item and that all have been happy.

 

[Sputty]

.

[neilestrick]

Since it shouldn't be used to show the actual accurate temperature in the kiln (that's what cones are for), but rather show rate of climb or approximate temp, or if it's holding, etc., the cheap ones will work fine.

[tomhumf]

Well, I decided to get the cheap eBay one. Sputty, I did check bath potters but the cheapest option for my temp is a type R set which would be £210 Inc delivery.  I'm watching one of the Fluke ones you suggested too Mark, will get one of those if it goes cheap, they look funky. 

Thanks

[curt]

They are much cheaper than the numbers being discussed here on eBay.  You can find  basic type Ks for $10 to $15, usually out of China or HK if you watch. I have bought a couple just to have them around, but since I always use Type R I can’t (yet) attest to their, ahem, longevity.   Type Rs much more expensive and rarely available on EBay.

[Rex Johnson]

Glad this was posted. I bought a Chinese digital  pyrometer thats just O.K., connection is spotty at best.

I have 3 standard non-digital pyrometers that are pretty old as well, they all read different temps.

Thinking of investing in one good unit I can move from kiln to kiln.

What's the best bet? What do you folks like?

[curt]

Hone

9 hours ago, Rex Johnson said:

Glad this was posted. I bought a Chinese digital  pyrometer thats just O.K., connection is spotty at best.

I have 3 standard non-digital pyrometers that are pretty old as well, they all read different temps.

Thinking of investing in one good unit I can move from kiln to kiln.

What's the best bet? What do you folks like?

The pyrometers (the device that shows the temperature, NOT the part that goes in the kiln, which is the thermocouple) almost always seem to be made in China, and they seem almost to be universally poor quality, and or start breaking apart after only a dozen or so uses.  Consistent with what Mark said, my impression is that Fluke is better, although they need to be because they always seem to cost ALOT more.  Maybe you get what you pay for, but it seems a lot to pay for what at the end of the day is a simple temperature reader.

The analog pyrometers, the old meter-with-a-bouncy-needle (which I assume is what you mean by “non-digital”) are really not accurate enough (or more specifically “precise” enpugh) to be helpful at managing a combustion kiln at higher temperatures.  You need something that can easily show you temperature variations over a ten to twenty degree range, ideally down to a degree at a time, particularly when you need to anticipate and react when the kiln is moving from reduction to oxidation, and vice versa.  Or at least that is my experience.

All this said, the basic job of a thermocouple is to use the junction between two different metals to turn the heat those metals are being exposed to into a small but readable electrical current...

for this reason...Honestly, the best - and cheapest - overall solution I have seen yet (and frequently use) is just to get a basic digital multimeter available at any electronics store or hardware store and hook it up to your thermocouple.  Set the multimeter to read millivolts (or whatever the smallest volt reading available is), and then read the millivolts from the meter as you are going along in the firing.   This millivolts number can be converted easily to an equivalent temperature.  For every type of thermocouple (K, R, N, etc), there are free conversion tables downloadable from the internet which convert millivolts from that type of thermocouple to an actual temperature reading.   This is plenty good enough for monitoring progress throughout most of the firing, and near then end of the firing you are definitely going to be watching your cones through the peephole anyway to see where your firing/heatwork is REALLY at.  

And voila! The poor mans pyrometer!  If the multimeter breaks...just buy another one!  They are cheap!

 Curious if others have used this technique?

 

[Mark C.]

You can buy a new fluke for a few hundred-I did long ago and it was the 51/KJ but as I said earlier this are now very dated except they work justas the newer ones-rock solid and cheaper than all the new junk ones-just be patient and find them on flea- bag.

 

[Rex Johnson]

Thanks Curt.

Guess I'll get another digital. I'm seeing Fluke 51 K/J  duals for under $50 on Ebay.

Any opinions on how long a thermocouple lasts?

I have several of those too.

example:

Fluke 52 K/J Two Channel Digital Thermometer Calibrated

[neilestrick]

Thermocouple life depends on temperature and kiln atmosphere. I've seen them go 50 firings and 300 firings. If you put it in a protection tube, it'll last a lot longer.

[Mark C.]

Rex that is a two kiln or two thermocouple one-I have one of those . You do not have to use both so it works well for one as well. These are nice units and at one time where state of the art. I these every week in all kilns and have a few spares as well.

[curt]

Mark, are you typically using K type thermocouples for your cone 10 firings?  Are yours sheathed? 

Some K’s I see for sale talk about going to 1300 C (most do not), but I am always in doubt as to whether or not they could replace my R type, or how long they would stand up to regularly going to those temps.

Thoughts?

[Mark C.]

Yes -I use type Ks in both my cone 10 kilns and my salt kiln-they are all sheathed-I seam to fire about 25-30 glaze fires a year in both kilns and they last many  many years.

When they go they give strange readings. I stock spares so no ordering last minute.

I buy the thicker wire ones from Laguna vs the thin cheap e-bay ones-as they last much longer. Axner sells them for online in the US ordering.

I always protect my thermocouples . I for many years cast my own tubes from porcelain from a mold I made-the tubes are about 12 inches long as are my thermocouples.

One other note is I also use a oxygen meter in both kilns as well. I fire reduction to cone 11.I have two of those a as well nd they are platinum and they are not sheathed.

That way my wife can check the kiln as its not a seat of the pants fire  like I can do my whole life,its a number so I do not have to be at kiln and can go into town as she can check that number and adjust if needed.