# Seeking Pyrometer Recommendations.



## Ray C (Dec 6, 2012)

Hi All,

Has anyone used this kind of a pyrometer and do they work well in the higher temperature ranges?  I'm looking for something suitable for heat treating so the common ones (which top-out around 700 F. won't do).

http://www.ebay.com/itm/50-1-Digita...846?pt=LH_DefaultDomain_0&hash=item4d078a7b56

Thanks

Ray


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## pdentrem (Dec 6, 2012)

I would not trust these kind of IR readers. They are dependent on black body radiation, also called emissivity, as the metal starts to glow the colour change can cause the readings to shift. We have one for low temp stuff, but to get more accurate readings I have had to place a piece of die grade carbon on top of the molten metal. Ours is a older unit that is not adjustable by the user, cost a bit more than the current one shown. Maybe they are getting better.

For same money get something better.

We use a digital reading handheld unit, not exactly as shown, like the one below. You can get also get all sorts of probes with varying lengths of lead wire from EDL-inc.com.

http://m.riogrande.com/Product/Hand-Held-Digital-Pyrometer-with-Thermocouple/703099

In using a probe like this, one places the sensing tip as close to the part that you are heating as possible if they are loose in the muffle, if the parts are in a closed box in the muffle or like in our annealing furnace the probes are approx centered in the hot zone. 

I am currently building a new heat treatment oven from spare parts and left overs for the shop. It will be a long tube muffle and likely we will be using a heavy steel box with a tap hole and feed tube for Nitrogen to purge any Oxygen from the box. There is a hot and cold zone in the muffle, so once the heating cycle is done the box is moved into the cold zone and after removed and emptied.

 The temp controllers are Watlow units. One is the set Tempurature and the other is the Hi limit in case the first one fails.

http://www.watlow.com/products/controllers/ez-zone-pm-express-pid-controller.cfm
Pierre


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## Ray C (Dec 6, 2012)

Thanks Pierre,

I appreciate the thoughts.  I'm in the process of building a heat treat oven and would prefer not to learn from the school of hard knocks.  I'll check-out those links soon.

Thanks

Ray


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## DMS (Dec 7, 2012)

Here is a industrial temp controller from Omega

http://www.omega.com/ppt/pptsc.asp?ref=CN7500&Nav=temp03

It's pretty similar to the one Pierre posted.

It will show you the temp, AND control your oven (just add a large solid state relay, and a thermocouple). Every kiln/heat treat oven I have seen has used a thermocouple for temperature sensing, so, I think that's where the sweet spot is.

I was thinking about building an oven myself a couple months back. After pricing things, and contemplating yet another project, I ended up buying a small Paragon kiln (the SC2). It has a fairly small cavity, but it is fine for you small stuff I have done. Just keep in mind, it may be cheaper to buy then build, depending on your requirements, and what you have laying around.

The other thing I will mention is that for high temp kilns, you will most often use kanthal elements. The problem with these is that they don't last very long in a neutral or carburizing environment (they need an oxidizing environment). If you are going to be using a purge gas, that is something to keep in mind.

I'll also post this

http://budgetcastingsupply.com/

These guys have everything you need to make a kiln, including controllers, sensors, relays, and refractory. If you can source refractory locally you will save a lot on shipping.


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## pdentrem (Dec 7, 2012)

Omron is another supplier of controllers as well.

http://www.ia.omron.com/products/ca...rature-controllers/general-purpose/index.html


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## Tom Griffin (Dec 7, 2012)

Ray,

If you want to go the inexpensive route, *Light Object* sells a PIC temp controller for about $36. Combine that with a type K thermocouple (McMaster Carr) and a relay to cycle the furnace and you will be good to go.

Tom


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## Ray C (Dec 7, 2012)

All,

Thanks for all the tips.  I'm going to create another thread -probably in the welding/casting section to talk about this heat treating oven.  This thread was put in metrology since I was looking for precise temperature measuring equipment.

Stand by till later today for the other thread which will have "Heat Treat" in the subject line.


Ray


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