Thermocouple Life Span

You can go up to about 1800 C with a type B. Are you using a thermowell? You should be.

That doesn't sound right as thermocouples used correctly generally don't fail. Are you sure they are not suffering mechanical damage?

Are the thermocouples being subjected to vibration, bending or excessive handling?

If so then you need to either support them better or try a different type of temperature sensor such as an encapsulated or sleeved thermocouple, etc. The right sensor for the right application.

Glass is very corrosive at these temperatures so you should use the correct tubing - I would try aluminum-nitride.

Any metal (including platinum) will go into solution either as oxide or as nanodispersed metallic clusters of a few 100 to 10000 atoms per cluster or as solid solution of metals in glass.

RHABE

Talk to your thermocouple supplier...either their products aren't performing as they should, or you're using the wrong product for that application. They will be able to advise.

Then contact a couple of other suppliers and check the answers

I have used:

TC-Direct: their K-type t/c lasted for 3 - 4 years underneath buses (we fitted them as a stop gap!)

Watlow: High tech automotive grade t/c used in our production products.

You don't say where you are, so there's a UK and a US supplier there.

Good luck

Type B: Platinum-Rhodium(30%) At 1000 deg C 9uV/deg C change

Continuous use +100 to +1600 deg C

Short term +50 to +1750 deg C

BS4937 part 7, ANSI/MC96.1 type B, DIN IEC B8, NF C42-321, JISC 1602

It would certainally apeare you are using the right type of thermocouple. The problem may be elseware as others have suggested. A higher rating type would be W (Tungsten) Up to +2600 deg C The change in voltage would be 20uV/deg C @ 1000 Deg C

Ive being using type K in a heat exchanger at 360 deg C for 10 years, no problim yet.

Many manufactures make TCs to withstand the temperature that you are working at... (cutting costs)... We had TC type K... that where lasting 6 to 12 months....

We then changed suppliers.. now using Endress Hauser ... Our TCs have been in service for 3 years running working with a temperature of 950ºC 24 hrs per day 365 days a year.

I have used for more than 25 years thermocouple in glass processing and melting. You need to know glass chemistry if your thermocouple is expoused to the glass vapor.

The life goes to more than 5 years since I have one which has not moved a 1C in 5.3 years if you can take care of protecting your thermocouple tip from glass vapor and furnace contamiantion.

If you need further help I can send you drawing and design how to do that

Got some insight there guys. Masyood, I will be very gratefull if you can provide me with the drawings.

If I have email will do that. I do not think you need this type of information in public domain.

you can always send email since I have business and may take few days to send that

It should be in the manufacturer spec or call them up.