Temperature Comparisons: 50ml Core vs 200ml Core

[RR1]

During temperature mapping of our fridges we have placed a temperature probe in 50ml liquid load to compare against the equipment 200ml liquid load. According to the results obtained the temperature within the 50ml volume runs about 0.5'C to 1'C LOWER than recorded in the 200ml load, depending on location.

As we all seem to use a 200ml volume for "core" temperature monitoring, and especially in the U.K as recommended in BS4376, is this then really incorrect??

If we hold small 50ml volume neonatal RBC packs then it's possible that these could be stored below the 2'C lower temperature used in the UK, if the fridge temperature drops to 2.5 to 3'C. Should we all be monitoring our temperatures using smallest component volumes?

It would be good to hear from others that may have performed similar comparisons too.

[Eagle Eye]

we use thermometer in a glycerol bottle with only 20 ml glycerol in it. Even probe which comes with referigerator has a bottle which holds only 20 ml of liquid.

so we measure temperature of lowest volume we would store in ref. I am in US.

[ckcheng]

I wonder what do you mean by 20 mL glycerol. The bottle comes with the blood fridge should be able to hold around 200 mL liquid and we put about 200 mL 10% glycerol in it. Also, 4 inches of the probe should be immersed in the glycerol.

Rashmi, when you placed the probe in the 50 mL liquid, did most of the probe immerse inside the liquid?

CK Cheng, MSc, SBB(ASCP), CQA(ASQ)

Hong Kong

[RR1]

Thanks aakupaku, it probably is best to monitor on the smallest component - as this will more likely be affected by temperature fluctuations.

Some folk use Glycerol (different concentrations) or just water to monitor on, I don't suppose it really matters that much.Our proble was properly immersed, using a smaller bottle to hold the liquid.

[Eagle Eye]

I buy thermometer which comes with liquid in bottle and thermometer....this is in addition to the bottle comes with referigerator.