AMcCord Posted July 30, 2008 Share Posted July 30, 2008 This is directed to those folks who are using infrared thermometers to check unit temps. How did you validate the thermometer?Thanks for your assistance! Link to comment Share on other sites More sharing options...
Franklyn Posted July 30, 2008 Share Posted July 30, 2008 Although I know we often use the terms interchangeably, but because I am a geek I feel this deep seated need to clarify You do not need to validate an IR thermometer, you merely need to calibrate it. We calibrate our IR Thermometers against our NIST at multiple points between -30 and 30 degrees C. The only caveats on calibration are that IR thermometer beams are adsorbed by liquid. So you cannot shoot a waterbath and get a valid temp. You can, however, shoot it at heat blocks, drawers and shelves, liquid filled blood bags, etc. We have been using an IR thermometer for about 10 years now and calibrate it annually against an NIST source with a +/- 1 degree C acceptable range. They are real gems to have. Link to comment Share on other sites More sharing options...
AMcCord Posted July 30, 2008 Author Share Posted July 30, 2008 Be my guest to clarify...my brain and my fingers get all disorderly sometimes.I can tell already that I'm going to love ours! It would have saved me a 2 AM phone call this morning. Link to comment Share on other sites More sharing options...
Lcsmrz Posted July 31, 2008 Share Posted July 31, 2008 There are alot of Blood Bankers -- esp old Blood Bankers -- who don't like the temp guns. They measure surface temp (which changes very quickly) and are subject to the emissivity (how efficiently heat is given off by the material). They are thought of as less accurate than a NIST-traceable Liquid-In-Glass thermometer, so many sites use them as a screen (if out-of-range, retest with LIG thermometer).I felt the same way, until I had lunch with a Metrologist many moons ago, who changed my views on temperature measurements forever ... Link to comment Share on other sites More sharing options...
Mary** Posted July 31, 2008 Share Posted July 31, 2008 What brand is the thermometer? Link to comment Share on other sites More sharing options...
AMcCord Posted July 31, 2008 Author Share Posted July 31, 2008 My new baby is SP brand, oval shaped, about the size of the palm of my hand, attached to a lanyard. It has one button to push with a simple digital readout. It's slick! Link to comment Share on other sites More sharing options...
Franklyn Posted July 31, 2008 Share Posted July 31, 2008 IR thermometers are commonly user by heating and air conditioning companies. As such you can purchase them rather cheaply from suppliers like Grainger or McMaster Carr. They do have their limitations, but can be really handly suckers to be sure... Link to comment Share on other sites More sharing options...
zz243 Posted July 31, 2008 Share Posted July 31, 2008 Many years ago we looked into IR thermometers but found the manufacturers insert promised a reading accuracy of +/- 2 degrees C of the actual temperature. Therefore, we did not buy them. Link to comment Share on other sites More sharing options...
Franklyn Posted August 1, 2008 Share Posted August 1, 2008 Both the AABB and CAP standards have been expanded from +/- 1 to +/- 2 degrees C ranges and, even better, many of the current crop of IR thermometers are accurate to +/- 1 degree or better. Link to comment Share on other sites More sharing options...
sticksjr Posted August 6, 2008 Share Posted August 6, 2008 It is recommended for users to "validate the IR Thermometer" "A confirmation or guarantee of the accuracy." Comparing the IR reading to a known source. ( which is not easy ) Calibration requires making adjustments to the instrument - usually performed by the manufacturer or calibration lab. IR Thermometers are quick and easy temperature monitoring devices. However, there are "many" pitfalls to infrared when used by untrained personnel. Understanding distance ratio, emissivity and keeping the optics clean and free from obstruction are all important for proper use. Be careful. It would be best use an IR device that has "emissivity" adjustment. Low cost models do not have this. Also determine the best distance to take a reading by understanding the units ratio specification. Link to comment Share on other sites More sharing options...
sgoertzen Posted August 6, 2008 Share Posted August 6, 2008 We bought a ThermoTrace IR w/Laser from DeltaTRAK and have returned it for a replacement, which also doesn't seem to work correctly. I can point it at a unit of blood sitting in our refrigerator at what I know is 3 C, and it will show the unit is 7 C. Whatsup with that? The manufacture "certified" it was working properly, but it sure doesn't seem like it to me. I would like to use it, but I don't trust it. Link to comment Share on other sites More sharing options...
sticksjr Posted August 6, 2008 Share Posted August 6, 2008 How do you specifically measure the temperature? Is the refrigerator door open? How far away was your infrared instrument from the bag? is the blood in a bag or vial? Also, refrigerators have a temperature gradient from front to back. Check the blood in the back - they might be cooler. Link to comment Share on other sites More sharing options...
Franklyn Posted August 7, 2008 Share Posted August 7, 2008 Don't forget to gently mix the product prior to reading the temperature. In liquids, temperature is not necessarily consistent with agitation. Thats why you have to stir the container of ice and water when calibrating in that fashion. I cannot put a finger on what we are doing differently, but our IR therms have not drifted outside of the +/- 1 degree C range in their entire history within the department and we calibrate them against an NIST therm that we send out annually for certification.Odd that you would see such a discrepancy... do you have a procedure that clearly describes how to use the IR Therm? Something that would allow consistency in training and eliminate or reduce that variable? Link to comment Share on other sites More sharing options...
sticksjr Posted August 12, 2008 Share Posted August 12, 2008 Although your infrared thermometer meets the calibration test, keep in mind that the calibration test/procedure is in a controlled environment - ie: pointing the IR thermometer at a blackbody ( known source ), at a specific distance by a trained instrumentation person.Field of View or Distance Ratio is ONE important component of accurate IR measurement. Think of the IR Thermometer as a Pen Light. If you hold the pen light over your desk about 2" away you will see the light image of a 1/4" circle . When you move the pen light further away the circle gets bigger. 12" inches away the light image is now much bigger in diameter. Now you're viewing/measuring a much bigger area of the blood bag.. The IR Thermometer mentioned earlier by sgoertzen has an 8 to 1 ratio. 8" away from the blood unit has a measuring area of 1" circle/diameter. Movie it closer 4" and you're measuring 1/2" diameter and 2" away you're measuring a 1/4" diameter.If the operator is measuring the unit of blood 24" away the measuring area is now 3" diameter. The laser beam is just a pointing device.The warmest temperature of the unit of blood will be on the outside surface and measuring the blood temperature through a plastic bag will introduce an error if the emissivity is fixed at .95. I checked with an expert who said IR thermometers would need to be set to .85 emissivity to allow for the clear plastic bag.I agree with a previous post that stated the use of an IR Thermometer should be used as a screen ( Go / No Go ) and if out of range use a NIST certified surface thermometer held on the bag for about 8-10 seconds. Link to comment Share on other sites More sharing options...
sgoertzen Posted May 20, 2009 Share Posted May 20, 2009 Franklyn, what exact kind of IR thermometer are you using? I bought one (not too expensive)and it consistently reads 2 degrees too warm. I hear there are good ones out there, but I haven't had any luck so far. Link to comment Share on other sites More sharing options...
Franklyn Posted May 26, 2009 Share Posted May 26, 2009 (edited) We have several brands in use and have bought them from Grainger. They provide the specs (+/- degrees) and we just choose one that falls within our specs. While I have never had to make an adjustment, most of these thermometers to allow the user to tweak the reading. It is usually a set-***** arrangement but would allow you to compensate for drift.Oddly enough, the language filters will not let me use the common word that describes a "a simple machine of the inclined-plane type consisting of a spirally threaded cylindrical rod that engages with a similarly threaded hole" - go figure Edited May 26, 2009 by Franklyn Link to comment Share on other sites More sharing options...
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