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Thread: Blood Storage Equipment Management: MU / Tolerance Settings

  1. #1
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    Blood Storage Equipment Management: MU / Tolerance Settings

    I’m writing some guidance on equipment management, and fridge temperature settings and alarm points seems to be an issue across pathology, and I would appreciate some help particularly as MU (Measurement Uncertainty) the term used by UKAS is causing confusion and a lot of unnecessary time spent trying to address this-and it would be useful for us all to get it right.

    So please comment on the following points: - are these assumptions correct/ incorrect/ overkill?

    1.MU (Measurement Uncertainty- term used by UKAS) = Tolerance (term used by MHRA inspectors) = Error or variation to the actual temperature value. So therefore the same thing?

    2. For blood storage equipment the final tolerance (MU, which can be found on the calibration certificates) should be no greater than 0.5’C to the primary calibrating equipment (traceable thermocouple) - the equipment used to calibrate the engineers testing probes (so add the MU between thermocouple to engineers equipment and then the MU between engineers equipment and your temp probes= no greater than 0.5’C) ?

    3.The MU of the temperature monitoring/ alert probes is used to determine the alarm settings for the fridges etc.- so, if the final MU is 0.36’C (round this up to 0.5'C), then the blood fridge CORE temperature alarm would be set min: 2.5’C and Max: 5.5 ‘C instead of 2'C to 6'C ( with no alarm delay ) . Similarly, the AIR temp alarm would be set Min: 2.5’C and Max: 7.5’C instead of 2'C to 8'C and a suitable/ justified delay set to prevent false alerts caused by routine opening/ re-stocking.

    4. I don’t know if anyone else has this issue- but after receiving calibration reports and certificates I usually have to contact the company to provide the certificate for the equipment used to calibrate the engineers probes- am I doing this right shouldn't this be routinely provided or is there an easier way?

    There are so many other equipment issues I would like to discuss so perhaps we could use this thread to include these- particularly:

    • Temperature mapping and position of monitoring probes
    • Fixing probes inside equipment/ cold rooms etc
    • Reviewing mapping reports and calibration certificates
    • Managing temperature excursions outside of routine hours- particularly with wireless monitoring equipment ........ and lots of other things!!!


    Many thanks,
    Rashmi
    Last edited by Rashmi; 25th Nov 2018 at 11:12 PM.

  2. #2
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    Hello , PHSS guidance on cold temperature storage on monitoring and mapping is my go to
    it’s free from PHSS.co.uk

  3. #3
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    Please see response below received from Mike Dawe about settings:
    MHRA take a more simple approach than UKAS. The minimum expectation is that probes are appropriately calibrated against a traceable standard, we would expect an accuracy of at least +/- 0.5°C on fridge probes and at least +/- 1°C on ambient probes. As long as that accuracy is achieved MHRA don’t have an expectation that the uncertainty is accounted for when setting the alarm limits. We are aware that UKAS do often ask for this and wouldn’t have a problem if a site had adopted this approach i.e. alarm settings should take into account the probes MOU i.e. if its 0.5 at 2 and 0.5 at 6 then the alarms should be set, tested and validated at 2.5 and 5.5. I hope that makes sense (please make sure they are set the correct way around)?


    bw
    Rashmi

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