Verify oven temps?

I bought a thermometer that goes to 2100 and two thermocouples that work on it, an my oven. This way I can cross check my PID on the oven, and I have an extra thermocouple just in case.
 
i4Marc said:
How do I go about verifying the temperature accuracy of my Evenheat KH418 oven? Do I just stick a pyrometer probe inside the door of the oven? I have the pyrometer in the link below. Aside from a ceramic sheath for the probe what else would I need? Is the pyrometer in the link accuarate enough to verify my oven temps?
https://www.auberins.com/index.php?main_page=product_info&cPath=17&products_id=199
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it should be. to verify my kiln, i put 3 thermocouples with 3 different displays within an inch of each other in the center of the furnace. at 1500*F, the three displays showed a total difference of 15*F, close enough for HT of O1 or 52100. to get a good reading, the probes should be as close together as possible.
 
Ok, so this is what I'm getting. Oven seems to be reading between 14˚-17˚ hotter than my Auberins pyrometer (@1500˚ f). Is this normal? Is this something I need to fix or is it worth it to fix? Or do I just set my oven temps 15˚ lower when I program the heat cycle?

URjVzG0.jpg
 
I'd measure boiling water with your handheld before drawing any conclusions.
 
You can also check it with ice water. After the ice is in the water for 10 minutes it should be 32 degrees. Distilleries and breweries calibrate their systems this way.
 
as already mentioned have read online regular table salt turns to liquid at 1400 F. does each device have an accuracy specification ? i can understand it must be hard to decide which one to trust.
 
I think that I have heard of people using tempstick crayons as well. I have some if you want them. Only up to about 500 degrees though
 
how far apart are the ends of the thermocouples? you want them as close as possible. a 15*F difference between places in the kiln are to be expected. the readings show a 1% difference, if you check the manuals that came with kiln and pyrometer, that is probably within spec. if that small error is driving you nuts, decrease the kiln setting by 8*F.
 
i4Marc said:
Ok, so this is what I'm getting. Oven seems to be reading between 14˚-17˚ hotter than my Auberins pyrometer (@1500˚ f). Is this normal? Is this something I need to fix or is it worth it to fix? Or do I just set my oven temps 15˚ lower when I program the heat cycle?

URjVzG0.jpg
Click to expand...

I set my oven based on the temp I tested the steel at for heat treat. Run a few coupons 10f apart, and use the setting with the best as quenched hardness.
 
I measured a pot of ice water as suggested. There were a couple of spots that measured in the 32.something range but most spots averaged about 34˚. This kinda makes sense since if it was 32˚ it would be in the process of freezing. The pot of ice water will only get warmer. So it appears that my meter isn't too bad. I think it's working ok.

naOhOQz.jpg


That brings me back to the oven. If I am plate quenching AEB-L or Nitro-V that takes my quench oil out of the equation. I recently got a new bucket to cross that variable off my list. So if the oven is not giving me similar readings to my meter, is there a way to make my oven more accurate? Or do I need to live with the discrepancy and try to compensate with my heat treat?
 
i4Marc said:
I measured a pot of ice water as suggested. There were a couple of spots that measured in the 32.something range but most spots averaged about 34˚. This kinda makes sense since if it was 32˚ it would be in the process of freezing. The pot of ice water will only get warmer. So it appears that my meter isn't too bad. I think it's working ok.

naOhOQz.jpg


That brings me back to the oven. If I am plate quenching AEB-L or Nitro-V that takes my quench oil out of the equation. I recently got a new bucket to cross that variable off my list. So if the oven is not giving me similar readings to my meter, is there a way to make my oven more accurate? Or do I need to live with the discrepancy and try to compensate with my heat treat?
Click to expand...
a 1% error in your readings is not going mess up your HT. over half of your "error" can be explained by the accuracy of the displays. again, unless the tips of the thermocouples were within less than an inch of each other, that would explain the other half
 
Scott,

I only had one thermocouple to check the readings.


Josh,

I don't know. My oven is about 6-7 years old. I know what an SSR is but a lot of you guys are more technically minded than I am. I don't know what all the different components are and how they play together.
 
Marc, Scott is talking about the TC that came with your kiln that is connected to your rampmaster. I would agree with him that if your pyrometer is in the front of the kiln and the TC that came with your oven is in the back then there could be a 15* difference between the two.

On my EH the TC is in the top dead center of the kiln. I'm not sure how you could get the pyrometer 1" away without rigging some kind of holder for it but its doable. Based on what you are showing above I would say you're probably fine in my opinion, but I understand the desire to confirm it.

-Clint
 
Marc, I didn’t know what the SSR was before I ordered my kiln a couple months ago. It’s a solid state relay and I’m sure a lot of people know a lot more than me, but apparently it regulates the temp electronically instead of mechanically. I could be wrong, I was just wondering if that would make a difference, but maybe it is the pyrometer.
 
The main benifit of the solid state relay is it fails open instead of closed. So when the relay goes your kiln will turn off instead of going into meltdown
 
I have an old Paragon with a peep hole in the door where I ran one of the thermocouples. you could drill a small hole in the door the same diameter as the thermocouple if you wanted.
 
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