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  1. #14
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    Quote Originally Posted by jim bergmann View Post

    You are correct, the NTC is slower than the k-type, but it is far more accurate.
    Quote Originally Posted by mark beiser View Post
    PT100 sensors are slower than k-type.
    NTC sensors are slower than Christmas!
    I have to disagree in part with both on this.

    If you have apples to apples with mass and contact area and then compare sensor types even the manufactures list NTC thermistors at the top as far as reaction time.

    RTD are fragile, more accurate in a range but slower than NTC.

    They list thermocouples (K-Type probes) the slowest with reaction time and accuracy but are well suited for high temperature measurements vs the other two.
    “If You Can Dodge A Wrench You Can Dodge A Ball”

  2. #15
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    Sparta, NJ
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    Mark
    I would be interested to see a pic of your solution on the clamp alignment. Any chance of posting it?

  3. #16
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    A simple groove cut into the opposite pad of the sensor like the other cheap clamps at Home Depot may help with alignment but as Mark said it may have to be perfect otherwise you are now locked into that spot and if the clamp goes out of wack your screwed.
    “If You Can Dodge A Wrench You Can Dodge A Ball”

  4. #17
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    Aug 2004
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    Quote Originally Posted by itsiceman View Post
    I have to disagree in part with both on this.

    If you have apples to apples with mass and contact area and then compare sensor types even the manufactures list NTC thermistors at the top as far as reaction time.

    RTD are fragile, more accurate in a range but slower than NTC.

    They list thermocouples (K-Type probes) the slowest with reaction time and accuracy but are well suited for high temperature measurements vs the other two.
    True, but when you get down to finished products, NTC thermistor probes virtually always have many times the thermal mass, and require much more contact area than a thermocouple or high end PT100 probe.
    If more government is the answer, then it's a really stupid question.

  5. #18
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    Quote Originally Posted by Doug at Testo View Post
    Mark
    I would be interested to see a pic of your solution on the clamp alignment. Any chance of posting it?
    More of a solution in progress at the moment. I've got maybe an hour invested in working on it so far, haven't had time for more. Things are crazy right now because it is our first >90º weather of the year, and next week will be >100º, so not sure when I'll have time to sit down and work on it.
    If more government is the answer, then it's a really stupid question.

  6. #19
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    Quote Originally Posted by mark beiser View Post
    True, but when you get down to finished products, NTC thermistor probes virtually always have many times the thermal mass, and require much more contact area than a thermocouple or high end PT100 probe.
    This NTC thermistor looks small in perspective to me and better contact than a bead type thermocouple
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    “If You Can Dodge A Wrench You Can Dodge A Ball”

  7. #20
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    Quote Originally Posted by itsiceman View Post
    This NTC thermistor looks small in perspective to me and better contact than a bead type thermocouple
    That's pretty tiny!
    I haven't seen a NTC thermistor probe available that uses a sensor that small. Usually they are pretty big, like the ones Cooper, Testo and Digi-cool use.

    I don't use bead type thermocouples. I use probes that have ribbon thermocouples in them, like the Fluke 80pk-8, and the Testo 0602 4592 pipe clamp thermocouple probe (expen$ive) for larger pipe sizes, and my Fluke surface probe. The nice thing about ribbon thermocouples is that they are wafer thin, the actual sensing portion is very small and has almost no thermal mass, and they will conform somewhat to the shape of the pipe, so it doesn't really matter if you don't have a perfectly straight section of pipe to hook the probe up to. They will work just as well on the inside or outside of a slight bend as they will on a perfectly straight section of pipe.
    Good probes that use ribbon thermocouples fight tightly to the pipe, have a solid "in the correct position feel", and back up the sensor with a dead air space.

    IMO, what a good quality ribbon type thermocouple lacks in raw accuracy vs a NTC thermistor, it more than makes up for in the ability to get a precise reading in less than perfect conditions in the field. There is also the issue of timeliness of the information displayed. My thermocouples react almost instantly to line temperature changes, The sensor in the typical NTC thermistor prob just can't react that fast.
    Last edited by mark beiser; 06-03-2010 at 09:26 PM.
    If more government is the answer, then it's a really stupid question.

  8. #21
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    Aug 2004
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    Decided to hook most of my pipe temp stuff up, just for grins.

    The instruments.


    The probes. One of the Testo 550 probes has some slight temporary improvements.


    1st and 2nd gen 523's


    2 Digi-Cool DRSA-1250's.


    Note the difference in the 2 temps on the 550. This is after fussing with the probes a lot to get the max reading I could get.
    The higher of the 2 is the probe with the orange weather strip on it.
    The probe in the Fluke 52 on the left, and the Testo probe in t2 of the Fluke 52 on the right are the probes I use, the other is out of my junk drawer.
    If more government is the answer, then it's a really stupid question.

  9. #22
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    Mark on the 550 clamp that you're working on you might try to pull that sensor into the clamping pad area 1/4" or so.
    I am only guessing but think some of that metal jacket on the cord end is to conduct to the wire itself and the actual tiny sensor inside there is located closer to the tip that is dead ended anyway. May help with centering also having the sensor closer to the middle of the clamp pad as well.

    Also comparing the 523's gets funny at a point.
    The time I've seen a difference like that or greater there is a difference like that where you have them mounted
    (temp of the pipe and temp of the room ambient)
    Is that the PT-100 Clamp on top of all those sensors there LOL
    “If You Can Dodge A Wrench You Can Dodge A Ball”

  10. #23
    Join Date
    Dec 2003
    Location
    Citrus County, Florida
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    1,400
    I used a set of 550 's today. I also placed a Fluke 52 with their 80pk (not sure of the number) quick clamp probe next to the Testo probe. Virtually no real difference. The Fluke read 1.3º lower; Fluke was last calibrated 10 yrs ago. Close enough for me. BTW: after reading about some 'problems" witht he Testo probes, I could not find any. I did make sure that the tubing was clean of junk and straight.
    Doug

  11. #24
    Join Date
    Feb 2006
    Location
    FL
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    mark, im wondering if you got some bum 550 clamps or something. whenever i compare mine they are really close. i must admit i dont have that many instruments and if i did that in my house my wife would think im crazy!!!

  12. #25
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    Quote Originally Posted by jvillehvac View Post
    mark, im wondering if you got some bum 550 clamps or something. whenever i compare mine they are really close. i must admit i dont have that many instruments and if i did that in my house my wife would think im crazy!!!
    Really close to what? If they all read the same equalized and at rest at Marks house what could be different about yours and his clamps
    “If You Can Dodge A Wrench You Can Dodge A Ball”

  13. #26
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    Feb 2006
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    FL
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    Quote Originally Posted by itsiceman View Post
    Really close to what? If they all read the same equalized and at rest at Marks house what could be different about yours and his clamps
    I didnt say mine were different than his, did I? As with any other mass produced product you plan on them reading the same. Real world, who knows. How do we know all that other stuff on there is right, oh thats right, digi cools and flukes are never out of calibration! I already tried all this when I first got mine 2 months ago cause like him I didnt want to blindly trust a new tool. Why mine arent off I dont know, go ask a testo engineer and let me know.

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