Hello all. I have a supplier of RTD elements that claims that their 1/10 DIN elements can maintain their tolerances from -200C to 450C.

IEC standards for tolerance class AA are only 0 to 150C, and 1/10 DIN tolerances are tighter than those.

Do any of you who use 1/10 DIN RTD sensors see that the tolerances are held even at these more extreme temperatures?

 

Interesting question. I'm interested in the replies.

 

the supplier in question will furnish whatever details are provided, if not check a different supplier

 

the supplier in question will furnish whatever details are provided, if not check a different supplier

I'm looking for end user experience. The supplier of the elements has already given me what the elements themselves are capable of. Once they are put into an assembly, resistances stack up and the results may well be different.

 

the answer to you question requires extensive lab test. I am sure your supplier will be more than happy to bid on your needs. Good luck.

 

Have you considered how you intend to use the RTD(s)? Will they be in a redundant arrange (dual redundant; triple redundant; 2oo3; etc.)? Do you require a high degree of accuracy in a specific range and are you worried about using a single RTD to measure the process variable in question?

What are you currently using for temperature measurement? Or are you designing a process/device requiring a wide range of temperatures and a high degree of accuracy?

Have you shared any of these considerations with the supplier? How many suppliers have you contacted with this requirement and the considerations?

Would some kind of redundant temperature measurement meet the requirements in the event of failure?

Are you looking at other, more expensive temperature sensing devices and wondering if there are more suitable, less expensive devices?

As others have suggested often times device/equipment suppliers can be very helpful when sourcing devices or equipment. Developing a relationship with supplier(s) is very important to getting satisfactory results. A supplier that want to acquire and KEEP customers is usually one who will work hard to earn your trust and work hard to maintain it. Are you working with a salesperson, or an application engineer with experience? Is the supplier the manufacturer of the devices or just a manufacturer's representative? Have you asked the supplier person you are working with what their experience is with similar applications? Or what the manufacturer's experience is with similar applications?

These kinds of decisions often come down to understanding all of the requirements of the application and having a trusted supplier. Yes, there are some "suppliers" that are just salespeople with little or no experience or even desire to help find the proper device for the application. That's why you should consider the effect of failed devices on your equipment/process and either design that into the equipment/process or look at other devices.

Someone else was asking recently if AI could be used to automate something similar (selecting devices/equipment). I don't recall many, if any, responses. There are a lot of variables and they all need to be properly considered. I have several personal experiences with major engineering design firms dictating which pieces of equipment (some were very large induction electric motors) they wanted, and it turns out the selection was based on price. The rotor of those motors was replaced three times--until the motor manufacturer sent someone to site to see the application and realized the entirely incorrect motor was specified and an application engineer of the manufacturer had never been contacted for assistance. This led to two unforced outages at a cogeneration plant, that caused extended delays at the host facility because of the lack of steam and heat for the process because of a lack of knowledge and an unwillingness to ask for assistance with choosing the proper motor (one with a rotor specially made to deal with reciprocating compressors).

 

Check out the last page of a vendor app note regarding special custom, "intensive" calibration of a particular RTD sensor, with claims of an 'AC' class accuracy over a very wide span of temperatures.

https://reotemp.com/wp-content/uploads/2015/11/TBRTDTOL-0614RTDToleranceClasses.pdf

 

The more the temperature moves away from zero the larger the tolerance for the class. As David_2 article notes you can tune a temperature transmitter to a specific RTD for higher accuracy. You need to look at accuracy of whole system, including temperature transmitter variation with ambient temperature and accuracy of instrument receiving the RTD/transmitter signal.

 

I am not the end user; I work for a company that manufactures temperature sensors. Most of our products are made for industrial users who request either class A or B. Rarely is 1/10 DIN class B ordered, but it does happen. With our limited experience at this tight a tolerance, I was looking for some feedback from others in industry who use them to get a better understanding of the ranges for use that can actually be expected, given the uncertainty in resistance readings that can add up for various reasons.