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  1. #1
    Join Date
    Apr 2002
    Location
    Currently: Denver Colorado area, Previously: East Coast to West Coast + many cities in between.
    Posts
    378

    Question Your Opinion Please!

    .
    I had three dual input Type-K thermocouple digital thermometers sent to me which are brand new right out of the plastic bubble pack.

    The manufacturer specified accuracy is in the temperature range of -328 to 2798°F, the accuracy should be ±(0.1% rdg +1.4°F)

    Please give me your opinion as to whether the tests pictured below indicate acceptable readings or not.

    1) I put all of the included thermocouples junctions together in air space and after letting them stabilize took this photo . . .
    http://i307.photobucket.com/albums/n...p-DSCN5195.jpg

    2) I put the included thermocouples in an ice bath, let the temperatures stabilize and took this photo . . .
    http://i307.photobucket.com/albums/n...E-DSCN5194.jpg
    Last edited by alexw; 06-15-2008 at 09:49 AM.
    Alex

  2. #2
    Join Date
    Mar 2007
    Location
    wedged in freezer shelf
    Posts
    6,723
    Looks like a lot of h20 and not a lot of ice in that cup.

    I goofed a few times before I learned you should not use tap water for the ice or water.

    I start from all ice in the insulated cup and let it melt by its self into water.

    If your water is hard and your ice comes out of a freezer you will be colder then 32°F and if you over do it with the h2o you will be warmer.

    Are there any adjustments you can make to those units?

    Looks accurate just not precise.

    “If You Can Dodge A Wrench You Can Dodge A Ball”

  3. #3
    Join Date
    Apr 2002
    Location
    Currently: Denver Colorado area, Previously: East Coast to West Coast + many cities in between.
    Posts
    378

    Thumbs down Can't Field Calibrate!

    .
    The UEI DT200 is NOT field adjustible/calibratable.

    My ice is pretty close to 32°F and there is definitely not as much difference in either the air or ice temperature as displayed between the instruments.

    This tells me that these DT200 thermometers are OK for approximate work but not for fairly precise measurement.







    Quote Originally Posted by itsiceman View Post
    Looks like a lot of h20 and not a lot of ice in that cup.

    I goofed a few times before I learned you should not use tap water for the ice or water.

    I start from all ice in the insulated cup and let it melt by its self into water.

    If your water is hard and your ice comes out of a freezer you will be colder then 32°F and if you over do it with the h2o you will be warmer.

    Are there any adjustments you can make to those units?

    Looks accurate just not precise.

    Alex

  4. #4
    Join Date
    Mar 2007
    Location
    wedged in freezer shelf
    Posts
    6,723
    If you can't adjust that sux

    Just buy plugging a different probe in a different socket you will probably get different readings.

    I mark my probes that I use on my Fluke 52 because after I calibrate the unit to one probe in the T1 socket and the other in the T2 socket they will be different if the probes get switched.

    say #1 probe for socket T1

    and #2 probe for socket T2
    “If You Can Dodge A Wrench You Can Dodge A Ball”

  5. #5
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    I don't know how much I would trust those little bead type thermocouples that come free with the meters.

    I've got 2 Fluke 52-2 dual input thermometers, one is brand new, the other is about 5 years old, 3 Fluke pipe clamp probes, a really expensive Testo pipe clamp probe, a Fluke surface probe, and a Fluke air probe.
    When exposed to the same exact temperature, the total temperature spread with any of the probes in either meter is 0.5ºF. This is at a variety of indoor temperatures in my house, with the probes clamped or strapped to a piece of 3/4" copper.
    I didn't go through the trouble of using distilled water, but just using crushed ice and water from the built in filtered dispensers on my refrigerator, the range was 32.1º to 32.5º, which is actually doing better than the listed accuracy of the meters and probes.

    When try the 2 bead probes that came with the new Fluke 52-2, the displayed temperature is about 1º higher than with any of the $70 to $175 probes plugged into either meter.

    The PT100 pipe clamp probe plugged into my Testo 523 is right in line with the the temperature I get with the expensive K-type thermocouple probes.
    If more government is the answer, then it's a really stupid question.

  6. #6
    Join Date
    Jun 2008
    Location
    south central pa
    Posts
    133
    i agree with mark fluke all the way. i currently have the 902 which i use the pipe clamp for s/h and s/c instead of the tape method. when i got my first one i couldnt believe anyone would use anything else. there are diffrent probes for speciffic uses. the bead probe is more of a jack of all trades not a specialty probe which is reflected in its low cost.

    all flukes can be calibrated but its best to send it back to fluke which costs more but you get what you pay for. one more thing, lifes too short to drink cheap liquor and use cheap tools. think of it as an investment.

  7. #7
    Join Date
    Jan 2009
    Location
    Texas
    Posts
    19

    Frown UEI Never again

    I'm looking at my second DT200 in less than two years. Right now it is telling me it is negative 7 degrees in my house. Same problem with the last one I had. It may be related to the cold weather around here, don't know, but I sure wished I bought Fluke to begin with. Amp clamp meter reads off when the battery gets low, but it still takes a couple days for the low battery light to come on.

  8. #8
    Join Date
    Mar 2008
    Location
    Rockwall, TX
    Posts
    99
    damn thats crazy. id be pissed! i have a dt 40 that works excellent. it is the best ive ever owned. it reads perfect with my fluke clamp. its like everytime i hook them up theres a chorus of angels singing.

  9. #9
    Join Date
    Jan 2007
    Location
    Mn the state where absolutey nothing is allowed
    Posts
    1,351

    UEI hit or miss

    ive got an old dt250 uei that has never been more than 0.5 deg off in ice water or boiling water adjusted for altitude. this is for the last 7 years running.

    but being the cynic i am ive borrowed a fluke 54 for the last few months( wont give it back untill he asks)

    well my UEI reads consistantly across the board 0.8 deg higher than the fluke. but its so consistant i'll still be happy with it when the fluke goes back to its rightfull owner

  10. #10
    Join Date
    Jan 2009
    Location
    Texas
    Posts
    19
    I'm like the features of the UEI meters when they are working right, and they are reasonably priced, but it's a real pain when they are not. I guess it's partly my fault, just looked at the book on the DT200 and it is only rated to operate down to 32 deg and it has been in the teens around here lately. Hoped it would work when I brought it inside and let it warm up, but doesn't seem to matter. The Fluke 50 series are rated down to 14 degrees operating temp and -40 storage temp, but with as much hype as Fluke gets, they only give a 3 yr warranty verses 5 for UEI. Can't decide what to do????

  11. #11
    Join Date
    Nov 2008
    Posts
    1,673

    matters of fact, matters of value, matters of opinion

    This is the first option, since they give the tolerance band, +/- 0.1% of rdg + 1.4℉

    rdg = 68.7,
    0.1% of 68.7 is 0.0687
    so it's
    68.7 + 0.0687 - 1.4 = 67.4
    and
    68.7 - 0.0687 - 1.4 = 67.2
    I'm not sure if you add or subtract the 1.4. I first thought you add the 1.4 but now I'm not so sure.
    Since the other meters read 70 I guess you add the 1.4.

    Anyway, the true value of the temp. is between
    67.2 and 67.4 (or 70.0 and 70.2) to a
    http://en.wikipedia.org/wiki/Confidence_interval
    of probably 95%.

    That is, the likelihood that the true value of the temp. lies within this interval is 95%. 5% of the time it will lie outside this interval, so I'd make several measurements and average them if this is important.

    I guess you can be 100.0% confident that the true temp. for this rdg. lies between 31℉ and 213℉, but you don't need a meter for that.

    For the rest of these I'd use a spreadsheet; it's too easy to make an arith. mistake.
    70.0
    70.5
    31.9
    33.7
    34.2

    Measuring temps. this precisely requires stirring to ensure even temperature distribution but not so vigorous stirring that it heats the mixture. I'd use a thermos bottle for this mixture.
    This is some of what NIST does for a living.

    Going about this the other way, you could ask the manu.,
    "With this tolerance, what should a properly working meter read if it's in a solution that is exactly 70.000℉?"
    That will settle the add or subtract 1.4 question.
    Now you've got me wondering. . .plus, this interpretation of tolerances has to be on the Web somewhere.

  12. #12
    Join Date
    Oct 2008
    Location
    New Jersey
    Posts
    1,015
    Quote Originally Posted by Engineman1 View Post
    I'm looking at my second DT200 in less than two years. Right now it is telling me it is negative 7 degrees in my house. Same problem with the last one I had. It may be related to the cold weather around here, don't know, but I sure wished I bought Fluke to begin with. Amp clamp meter reads off when the battery gets low, but it still takes a couple days for the low battery light to come on.
    I used to use UEI instruments but not anymore. I went through two DL389 clamp meters within a year. I used to be against fluke because i always thought they were overpriced, but since i started using fluke i will never use another meter manufac. I currently own the 902, 52-2, 322 and just ordered a 87-5. When it come to accuracy you cant beat fluke, the thermometer is very accurate, and is field calibratable.
    I dont install leaks, i just fix em

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  13. #13
    Join Date
    Oct 2008
    Location
    New Jersey
    Posts
    1,015
    Quote Originally Posted by Engineman1 View Post
    I'm like the features of the UEI meters when they are working right, and they are reasonably priced, but it's a real pain when they are not. I guess it's partly my fault, just looked at the book on the DT200 and it is only rated to operate down to 32 deg and it has been in the teens around here lately. Hoped it would work when I brought it inside and let it warm up, but doesn't seem to matter. The Fluke 50 series are rated down to 14 degrees operating temp and -40 storage temp, but with as much hype as Fluke gets, they only give a 3 yr warranty verses 5 for UEI. Can't decide what to do????
    IMO its worth it to go with the fluke, i know it sounds like im tryin to sell their products but they really are worth it. To this day i have never heard anyone who has had major problems with their fluke products. Me and a friend of mine both bought the DL389 clamp meter, my screen would shut off and his speaker wouldnt work, those were the first ones. The second one I got wouldnt read voltage, even though there was 460 there
    I dont install leaks, i just fix em

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    Lets see if this gets removed..............

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