Calibrating Thermocouples

Hi Guys,
I've got a customer who wants me to calibrate the thermocouples on their oven. These thermocouples(K-type) are tied to Flex I/O 1794-IRT8 modules. I have a couple of questions about this.

Is it necessary to calibrate the IRT8 module itself (it is supposed to be calibrated from the factory) or just to apply an offset for each thermocouple after testing it accuracy? My problem is I am having trouble finding a reasonably priced mV source to supply the needed +/- 320mV AB calls for in the calibration procedure (see attached Pub 1794-6.5.12 Section 6). That value seems a bit high to me anyhow for a thermocouple.

I intend to check the thermocouples with a dry well calibrator to determine if an offset needs to be applied. Would this be the correct way of doing this?

Thanks

I spend may hours per year calibrating temperatures, flows, pressures etc. A drywell is certainly the best, here we have the drywell checked once a year & obtain a calibration cert to UKAS standard (this is part of our procedures).
Cable lengths, types, cards etc. can all introduce errors.
Most plc cards do not come with certificates just a general specification, so I check all the way through from sensor to display the offset/zero (or zero/span) of the whole loop is checked, I insert the probe in the drywell, also a calibrated probe in the drywell (this gives a true reading of the temperature at the probe tip in the block), wait until it stabilises then adjust the zero or span acordingly, this is done at both ends of the range & repeated a number of times as adjusting the zero affects the span & vice versa.
our specs in the food industry are +- 0.7 Degrees C, however for ovens, heaters it probably won't matter quite so much.
We are audited every year & it is important that we can produce paperwork to prove the procedures are followed.

Possibly spring for certified thermocouples. That way there is a paper trail for auditors to salute.

we use a fluke model 725 process calibration meter.
we have to send it off 1 time a year for calibration.

regards,
james