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#1
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Thermometers: What's the Problem with Accuracy?
I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are. For Instance: - 4 thermometers of same make/model, hanging on the same rack. - Alcohol bulb/glass tube - you'd think basic physics... - Each reads a different temp from 68 to 74 degrees. Only thing I can think of is that the card behind the glass thingie is misaligned, but looking at these things, there does not seem to be enough physical room for those kinds of errors. Also, at home I have a couple of digital indoor/outdoor thermometers. Bring the outdoor sensor inside and put it right next to the master part, and they're a couple degrees different. Is there any hope at all of finding four thermometers which: - All read the same temp when placed side-by-side - Read the correct temp. What am I missing? -- Pete Cresswell |
#2
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Thermometers: What's the Problem with Accuracy?
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 |
#4
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Thermometers: What's the Problem with Accuracy?
On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands). Canada retains it as a supplementary scale that can be used alongside Celsius. -- Bod |
#5
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Thermometers: What's the Problem with Accuracy?
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#6
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Thermometers: What's the Problem with Accuracy?
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. For Instance: - 4 thermometers of same make/model, hanging on the same rack. - Alcohol bulb/glass tube - you'd think basic physics... - Each reads a different temp from 68 to 74 degrees. Only thing I can think of is that the card behind the glass thingie is misaligned, but looking at these things, there does not seem to be enough physical room for those kinds of errors. Also, at home I have a couple of digital indoor/outdoor thermometers. Bring the outdoor sensor inside and put it right next to the master part, and they're a couple degrees different. Is there any hope at all of finding four thermometers which: - All read the same temp when placed side-by-side - Read the correct temp. What am I missing? Spending enough money to get one that has a little quality control in the manufacturing phase? My Bacharach sling always shows to be the same as the lab grade thermometer we use to calibrate the instruments we use for state water samples but they cost $80+ Digital stuff itself is what I call the great lie. They give you a very precise reading, that is usually wrong. I have an $8000 (MSRP) digital water tester from the state that we have to calibrate before and after every use and about 10-15% of the time, they do not pass the verification calibration after the test on at least one parameter. |
#7
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Thermometers: What's the Problem with Accuracy?
On Sunday, February 4, 2018 at 12:54:53 PM UTC-5, Bod wrote:
On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands). Canada retains it as a supplementary scale that can be used alongside Celsius. I'm surprised you're surprised. Given the chauvinism rampant in the U.S., it's only to be expected. Cindy Hamilton |
#8
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Thermometers: What's the Problem with Accuracy?
In alt.home.repair, on Sun, 04 Feb 2018 11:51:08 -0500,
"(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. For Instance: - 4 thermometers of same make/model, hanging on the same rack. - Alcohol bulb/glass tube - you'd think basic physics... That only works if the bulb is exactly the right size and the amount of alcohol or mercury inside is exactly correct. I don't want to spend too much just to get accuracy that won't really help me. - Each reads a different temp from 68 to 74 degrees. Last time I bought a thermometer, about 40 years ago (not counting a digital one that claims to measure humidity), a glass one, there were about 8 on the rack and I looked at each temp and bought one whose reading was part of the cluster of readings very close to each other. What more could I do. Only thing I can think of is that the card behind the glass thingie is misaligned, but looking at these things, there does not seem to be enough physical room for those kinds of errors. I don't think the card is the problem. Glass thermometers sometimes or always have a scratch, a file mark, at 32 degrees, on one side of the tube, I've read. I've never looked closely and I've never seen the mark, but it makes sense (and it contradicts my first paragraph above, come to think of it). They'd put all the thermometers in a mixture of melting ice and water, maybe even in a refrigerated room. Pull them out one at a time and file the scratch wherever the level happens to be. Also, at home I have a couple of digital indoor/outdoor thermometers. Bring the outdoor sensor inside and put it right next to the master part, and they're a couple degrees different. Is there any hope at all of finding four thermometers which: - All read the same temp when placed side-by-side - Read the correct temp. What am I missing? Cynicism. Hopelessness. |
#9
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Thermometers: What's the Problem with Accuracy?
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#10
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Thermometers: What's the Problem with Accuracy?
On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote:
On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands). Canada retains it as a supplementary scale that can be used alongside Celsius. We use what we are used to. OTOH Fahrenheit gives you about twice the precision without resorting to decimals. I am comfortable with both since my science friends are all C |
#11
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Thermometers: What's the Problem with Accuracy?
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. For Instance: - 4 thermometers of same make/model, hanging on the same rack. - Alcohol bulb/glass tube - you'd think basic physics... - Each reads a different temp from 68 to 74 degrees. Only thing I can think of is that the card behind the glass thingie is misaligned, but looking at these things, there does not seem to be enough physical room for those kinds of errors. Also, at home I have a couple of digital indoor/outdoor thermometers. Bring the outdoor sensor inside and put it right next to the master part, and they're a couple degrees different. Is there any hope at all of finding four thermometers which: - All read the same temp when placed side-by-side - Read the correct temp. What am I missing? Pete, Maybe check here. I never knew so little until I bought a good unit for my outdoor meat smokers and instant read (few seconds) units. It can with a certificate of accuracy +/- . I very much doubt cheap units can be calibrated. "... Find info on instrumentation, sensors, measurement and control, calibration and a variety of commercial applications." https://www.thermoworks.com/learning-center |
#12
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Thermometers: What's the Problem with Accuracy?
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#13
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Thermometers: What's the Problem with Accuracy?
On Sunday, February 4, 2018 at 2:52:17 PM UTC-5, wrote:
On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote: On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands). Canada retains it as a supplementary scale that can be used alongside Celsius. We use what we are used to. OTOH Fahrenheit gives you about twice the precision without resorting to decimals. I am comfortable with both since my science friends are all C I've never understood the "precision" argument. Does it matter whether it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant. Cindy Hamilton |
#14
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Thermometers: What's the Problem with Accuracy?
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#15
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Thermometers: What's the Problem with Accuracy?
On Sun, 4 Feb 2018 13:29:51 -0800 (PST), Cindy Hamilton
wrote: I've never understood the "precision" argument. Does it matter whether it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant. Cindy Hamilton Think of it as "close enough for government work." Trust me I'm from the government, I'm here to help. ....or as Bubba says, "it looks good from my house!" |
#16
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Thermometers: What's the Problem with Accuracy?
On 2/4/2018 3:32 PM, (PeteCresswell) wrote:
Per : http://www.leevalley.com/us/garden/P...=2,40733,40734 But the question is: if you put five of those things side-by-side, how many of them will read the same temperature - and will it be the correct temperature. Ask Lee Valley for spec's and see if they are anything but fancied up Chinese imports or no...I'd guess probably not, but ya' never know 'til you ask. -- |
#17
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Thermometers: What's the Problem with Accuracy?
On Sunday, February 4, 2018 at 2:52:17 PM UTC-5, wrote:
On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote: On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands). Canada retains it as a supplementary scale that can be used alongside Celsius. We use what we are used to. OTOH Fahrenheit gives you about twice the precision without resorting to decimals. I am comfortable with both since my science friends are all C Exactly. Unlike the metric system for mass, length, volume, etc., there is no calculation advantage to using C over F. They are both 100 point scales invented by Europeans. The C scale is 100 degrees between freezing and boiling, the F scale is 100 degrees between how cold and how hot it normally got outside in Europe. |
#18
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Thermometers: What's the Problem with Accuracy?
http://www.leevalley.com/us/garden/P...=2,40733,40734 But the question is: if you put five of those things side-by-side, how many of them will read the same temperature - and will it be the correct temperature. They are accurate. Buy a more expensive one if you want ... http://tinyurl.com/y89uxh4j + / - 1 degree http://tinyurl.com/y9cc7re6 John T. |
#19
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Thermometers: What's the Problem with Accuracy?
On Sun, 04 Feb 2018 17:21:58 -0500, wrote:
http://www.leevalley.com/us/garden/P...=2,40733,40734 But the question is: if you put five of those things side-by-side, how many of them will read the same temperature - and will it be the correct temperature. They are accurate. Buy a more expensive one if you want ... http://tinyurl.com/y89uxh4j + / - 1 degree $ 100. .. http://tinyurl.com/y9cc7re6 John T. + / - 2 degrees for $ 10. http://tinyurl.com/y7bgvwrr John T. |
#20
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Thermometers: What's the Problem with Accuracy?
Per Cindy Hamilton:
I've never understood the "precision" argument. Does it matter whether it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant. My take is that when you're out in it a couple degrees, or even 1 degree F can be significant and it seems easier to say "Fifty-One: than "Ten-point-six". Or do people who use Celsius just drop the decimal and say "Ten-six"? -- Pete Cresswell |
#21
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Thermometers: What's the Problem with Accuracy?
On 2/4/2018 10:51 AM, (PeteCresswell) wrote:
I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. For Instance: - 4 thermometers of same make/model, hanging on the same rack. - Alcohol bulb/glass tube - you'd think basic physics... - Each reads a different temp from 68 to 74 degrees. Only thing I can think of is that the card behind the glass thingie is misaligned, but looking at these things, there does not seem to be enough physical room for those kinds of errors. .... Isotech TTI-22 True Temperature Indicator Thermometer with 0.001°C accuracy and 0.0001°C resolution And, it's a bargain at _only_ $6,073.00!!! But, you get: Includes FREE Ground Shipping FREE Lifetime Tech Support Omega has a line of low-cost glass lab thermometers but don't specify accuracy on them, either; they have others of lab quality that are $10+ or so each instead of $5-6. They used to have an ambient-air monitor that was pretty good that we used to use to monitor air temp around the boilers but it doesn't seem to be available any longer and the one other I looked at from another vendor was also listed as discontinued. That's all the time I had... The problem with inexpensive bulb thermometers is that the capillary dimension has to be exceedingly precise in order to control both the linearity and scaling and doing that drives the price up -- actually, like matching v-belts; to get precise ones they would just select from the run those that matched given calibration but as somebody else noted, the ordinary Walmart/drugstore/etc., ones will not have gone through much if any screening at all; what you get is a measure of the manufacturing process variability by doing the comparisons you've done. But, the time/effort required to do screening adds up so even moderately accurate ones get to be fairly pricey pretty quickly. If a bulb thermometer serves the purpose, probably one of the secondary-school lab suppliers or the like will be the best bet. -- |
#22
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Thermometers: What's the Problem with Accuracy?
On 2/4/2018 3:29 PM, Cindy Hamilton wrote:
.... I've never understood the "precision" argument. Does it matter whether it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant. .... Well, there's the same question around 212, too, from that standpoint... I ran into a minor instance here just recently -- fixed up a monitoring system in the well house to alert me if the temperature drops that indicates I need to go relight the gas heater (occasionally the high KS wind will manage to blow out the pilot). I used a cute little $6 digital thermostat module in "heat" mode to turn on an LED in the window I can see if temp drops below setpoint. I just stuck the RTD sensor inside the small project box I mounted the controller in and velcro-ed it to the wall near the power outlet on the plywood backer board for the electrical panel, etc. Since the block building walls aren't insulated, it gets pretty cool right on the wall surface so wasn't sure where would need to set the setpoint to not false alarm on really cold days even though the little heater keeps the bulk air temperature around 50F. Started at 5C -- 41F and we had some bitter nights shortly thereafter and it triggered. So, not wanting to try to cut it too close, 1F is ~0.5F so lowered it to 4.5F and added 3/4" of foam packing between the solid wood board mount and the unit. So far, it's not triggered again but it's not been below zero again since, either; we'll just "hide and watch" and see how it goes. But, long-winded that got me wondering; are European thermostats/thermometers registering tenths or are they using 1C setpoint tolerances? I can tell difference in our house between a 69F where we normally keep for winter and 70F setpoint; there's a significant run-time difference as well so if it were 20C or 21C that were the choices, the 20C -- 68F is notably chilly and so 70F would be next best granularity could get and that would, over time, be observable in heating bills. Not huge, but "yes, I think it can make a difference" in ordinary things... -- |
#23
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Thermometers: What's the Problem with Accuracy?
On Sun, 4 Feb 2018 13:29:51 -0800 (PST), Cindy Hamilton
wrote: I've never understood the "precision" argument. Does it matter whether it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant. Cindy Hamilton Yep. Pretty easy to tell if the milk is cold or the ice cream is melting. Out of curiosity I checked the 3 thermometers in my house. They are an "alcohol" wall thermo, digital thermostat, and digital meat thermo. All of them read 70F. Maybe those measuring cold are inaccurate. |
#24
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Thermometers: What's the Problem with Accuracy?
On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote:
On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands). Canada retains it as a supplementary scale that can be used alongside Celsius. -- Bod Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^ [8~{} Uncle Temperate Monster |
#25
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Thermometers: What's the Problem with Accuracy?
On 02/04/2018 03:33 PM, (PeteCresswell) wrote:
Per Cindy Hamilton: I've never understood the "precision" argument. Does it matter whether it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant. My take is that when you're out in it a couple degrees, or even 1 degree F can be significant and it seems easier to say "Fifty-One: than "Ten-point-six". Or do people who use Celsius just drop the decimal and say "Ten-six"? From what I've seen as far as weather goes fractional values aren't used. It's -2 in Berlin at 0500 and will hit a high of 2 with -6 overnight on Tuesday |
#26
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Thermometers: What's the Problem with Accuracy?
On Sunday, February 4, 2018 at 3:29:56 PM UTC-6, Cindy Hamilton wrote:
On Sunday, February 4, 2018 at 2:52:17 PM UTC-5, wrote: On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote: On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).. Canada retains it as a supplementary scale that can be used alongside Celsius. We use what we are used to. OTOH Fahrenheit gives you about twice the precision without resorting to decimals. I am comfortable with both since my science friends are all C I've never understood the "precision" argument. Does it matter whether it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant. Cindy Hamilton As far as human comfort goes, it's the humidity that counts. 72°F at 50% humidity is more comfortable 72°F at 90% humidity. I serviced and installed HVAC systems back when I was doing service work for businesses. I like 2 stage AC systems because they control humidity much better. The newest more advanced(more expensive) HVAC systems are variable giving a more precise control of humidity. ^_^ [8~{} Uncle Chilly Monster [8~{} Uncle Humid Monster |
#27
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Thermometers: What's the Problem with Accuracy?
Bod wrote: "- show quoted text -
As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use/" The scale used has nothing to do with the accuracy(or inaccuracy) of the thermometers Pete tested. |
#28
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Thermometers: What's the Problem with Accuracy?
On 04/02/2018 19:52, wrote:
On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote: On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands). Canada retains it as a supplementary scale that can be used alongside Celsius. We use what we are used to. OTOH Fahrenheit gives you about twice the precision without resorting to decimals. I am comfortable with both since my science friends are all C Understood, but C has become the universal standard. -- Bod |
#29
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Thermometers: What's the Problem with Accuracy?
On 04/02/2018 20:49, dpb wrote:
On 2/4/2018 1:52 PM, wrote: On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote: ... As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. ... We use what we are used to. OTOH Fahrenheit gives you about twice the precision without resorting to decimals. I am comfortable with both since my science friends are all C Precisely...since US doesn't have the culture that guv'mint can enforce stuff like this universally on the general public, popular usage remains (similar as to having kept almost exclusively other US/Imperial measures as well). I'm a nuclear engineer by BS, MS Physics (Nuclear Science) and spent over 30 year in the traces and still, while I'm capable of thinking through roughly what C corresponds to F and vice versa, it's still only just native F that really resonates; it's just the system that is ingrained. While in the reactor design world, all the nuclear calculations were in conventional metric units (scaled for the purpose, for example, nuclear absorption cross sections are in "barns", a barn being 10E-24 cm^2) but all the thermo guys were in English units so we consistently used core inlet/outlet temperatures of 555/605F and had (and still remember many) values of the steam tables such as that Tsat at 2200 psia is 649.45 F (although those are like 1977 Table values; they've been updated so probably a hundredth or few off currently-published numbers). I'm sure in the now almost 40 years since last actually worked inside a reactor vendor (spent last 20+ yr consulting for various utilities and US DOE rather than with vendor) the design protocol will have all moved to metric just for the consistency.Â* We began the process even while I was still at the vendor when teaming with German and French partners; their licensing authorities at the time required it although it never changed our practices in the US. The argument has raged forever and while there are valid reasons for metric in business and industry and inside those fields things have gone almost universally that way, there's just no overpowering reason that familiar units must change so the status quo remains and new generations continue to be reared with no practical day-to-day acquaintance with them so they also are only innately comfortable with F for temp and the cycle continues... -- I was brought up on Fahrenheit, but soon adapted to C which is so straightforward for everyday use once you get used to it and you soon get used to it. It's so much more logical with 0 being freezing and a 100 for boiling, IMO. -- Bod |
#30
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Thermometers: What's the Problem with Accuracy?
On 05/02/2018 00:34, Uncle Monster wrote:
On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote: On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands). Canada retains it as a supplementary scale that can be used alongside Celsius. -- Bod Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^ [8~{} Uncle Temperate Monster I grew up on Fahrenheit and the change to Centigrade was virtually seamless, you quickly adapt. So now I'm comfortable reading both scales, but C is so much more practical for everday use, plus it is the universal standard. Why stubbornly stick to last century thermal measurements! -- Bod |
#31
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Thermometers: What's the Problem with Accuracy?
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote in - Each reads a different temp from 68 to 74 degrees. For cheap thermometers, that's not bad. Just take the average of the four and then calculate the difference between the average and each of the four and use that as a correction factor for each of the four. That will probably bring you to a 99.9% accuracy for each of the four. -- Web based forums are like subscribing to 10 different newspapers and having to visit 10 different news stands to pickup each one. Email list-server groups and USENET are like having all of those newspapers delivered to your door every morning. |
#32
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Thermometers: What's the Problem with Accuracy?
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#33
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Thermometers: What's the Problem with Accuracy?
On Monday, February 5, 2018 at 12:33:16 AM UTC-6, Bod wrote:
On 05/02/2018 00:34, Uncle Monster wrote: On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote: On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).. Canada retains it as a supplementary scale that can be used alongside Celsius. -- Bod Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^ [8~{} Uncle Temperate Monster I grew up on Fahrenheit and the change to Centigrade was virtually seamless, you quickly adapt. So now I'm comfortable reading both scales, but C is so much more practical for everday use, plus it is the universal standard. Why stubbornly stick to last century thermal measurements! -- Bod We Americans are more ornery and resistant to changing our habits than other people of the world. ^_^ [8~{} Uncle Ornery Monster |
#34
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Thermometers: What's the Problem with Accuracy?
On 05/02/2018 07:37, Uncle Monster wrote:
On Monday, February 5, 2018 at 12:33:16 AM UTC-6, Bod wrote: On 05/02/2018 00:34, Uncle Monster wrote: On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote: On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands). Canada retains it as a supplementary scale that can be used alongside Celsius. -- Bod Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^ [8~{} Uncle Temperate Monster I grew up on Fahrenheit and the change to Centigrade was virtually seamless, you quickly adapt. So now I'm comfortable reading both scales, but C is so much more practical for everday use, plus it is the universal standard. Why stubbornly stick to last century thermal measurements! -- Bod We Americans are more ornery and resistant to changing our habits than other people of the world. ^_^ [8~{} Uncle Ornery Monster I've noticed, plus: Of all the countries in the world, only three still use the archaic Imperial system of weights and measures: Liberia. Myanmar (a.k.a. €śthe country formerly known as Burma€ť) United States of America. -- Bod |
#35
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Thermometers: What's the Problem with Accuracy?
"(PeteCresswell)" wrote:
I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. For Instance: - 4 thermometers of same make/model, hanging on the same rack. - Alcohol bulb/glass tube - you'd think basic physics... - Each reads a different temp from 68 to 74 degrees. Only thing I can think of is that the card behind the glass thingie is misaligned, but looking at these things, there does not seem to be enough physical room for those kinds of errors. Also, at home I have a couple of digital indoor/outdoor thermometers. Bring the outdoor sensor inside and put it right next to the master part, and they're a couple degrees different. Is there any hope at all of finding four thermometers which: - All read the same temp when placed side-by-side - Read the correct temp. What am I missing? Best way of testing bulb thermometers is insert in water beaker with stirring mechanism for rapid low. Add ice should be hear 32 degrees. Air currents can be tricky and scales can slip. +- 1 degree typical variance. My two outside units are at least 3 degrees off. Can't find easy way to cal. Some resistors probably need tweaked. Greg |
#36
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Thermometers: What's the Problem with Accuracy?
On Sunday, February 4, 2018 at 5:33:30 PM UTC-5, (PeteCresswell) wrote:
Per Cindy Hamilton: I've never understood the "precision" argument. Does it matter whether it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant. My take is that when you're out in it a couple degrees, or even 1 degree F can be significant and it seems easier to say "Fifty-One: than "Ten-point-six". Or do people who use Celsius just drop the decimal and say "Ten-six"? They would just say 10. At http://www.cbc.ca/windsor/weather/s0000646.html, the current temperature is -14 and today's high is expected to be -5. That's for Windsor, which is a short drive from where I am. Cindy Hamilton |
#37
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Thermometers: What's the Problem with Accuracy?
On Monday, February 5, 2018 at 2:52:26 AM UTC-5, Bod wrote:
On 05/02/2018 07:37, Uncle Monster wrote: On Monday, February 5, 2018 at 12:33:16 AM UTC-6, Bod wrote: On 05/02/2018 00:34, Uncle Monster wrote: On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote: On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands). Canada retains it as a supplementary scale that can be used alongside Celsius. -- Bod Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^ [8~{} Uncle Temperate Monster I grew up on Fahrenheit and the change to Centigrade was virtually seamless, you quickly adapt. So now I'm comfortable reading both scales, but C is so much more practical for everday use, plus it is the universal standard. Why stubbornly stick to last century thermal measurements! -- Bod We Americans are more ornery and resistant to changing our habits than other people of the world. ^_^ [8~{} Uncle Ornery Monster I've noticed, plus: Of all the countries in the world, only three still use the archaic Imperial system of weights and measures: Liberia. Myanmar (a.k.a. €śthe country formerly known as Burma€ť) United States of America. It's surprising how much "secret" adoption of SI has gone on here. Two-liter bottles of Coke. 750-ml bottles of wine. My husband has both metric and English tools in his workshop. And of course we use the same second as the rest of the world. Cindy Hamilton |
#38
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Thermometers: What's the Problem with Accuracy?
On 2/4/2018 11:51 AM, (PeteCresswell) wrote:
I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. For Instance: - 4 thermometers of same make/model, hanging on the same rack. - Alcohol bulb/glass tube - you'd think basic physics... - Each reads a different temp from 68 to 74 degrees. Only thing I can think of is that the card behind the glass thingie is misaligned, but looking at these things, there does not seem to be enough physical room for those kinds of errors. Also, at home I have a couple of digital indoor/outdoor thermometers. Bring the outdoor sensor inside and put it right next to the master part, and they're a couple degrees different. Is there any hope at all of finding four thermometers which: - All read the same temp when placed side-by-side - Read the correct temp. What am I missing? You have a refrigerator/freezer reading in the high 60s to low 70s. You have bigger problems than an inaccurate thermometer. |
#39
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Thermometers: What's the Problem with Accuracy?
On 05/02/2018 11:42, Cindy Hamilton wrote:
On Monday, February 5, 2018 at 2:52:26 AM UTC-5, Bod wrote: On 05/02/2018 07:37, Uncle Monster wrote: On Monday, February 5, 2018 at 12:33:16 AM UTC-6, Bod wrote: On 05/02/2018 00:34, Uncle Monster wrote: On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote: On 04/02/2018 17:11, wrote: On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)" wrote: I've been trying to buy four refrigerator/freezer thermometers and it's frustrating how inaccurate/inconsistent they are. http://www.leevalley.com/us/garden/P...=2,40733,40734 As an aside, I'm surprised that the US is still using Fahrenheit instead of the universal Centigrade. There's only about 8 countries that still use F. Fahrenheit remains the official scale for the following countries: The Bahamas, Belize, the Cayman Islands, Palau and the United States and associated territories (Puerto Rico, Guam and the U.S. Virgin Islands). Canada retains it as a supplementary scale that can be used alongside Celsius. -- Bod Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^ [8~{} Uncle Temperate Monster I grew up on Fahrenheit and the change to Centigrade was virtually seamless, you quickly adapt. So now I'm comfortable reading both scales, but C is so much more practical for everday use, plus it is the universal standard. Why stubbornly stick to last century thermal measurements! -- Bod We Americans are more ornery and resistant to changing our habits than other people of the world. ^_^ [8~{} Uncle Ornery Monster I've noticed, plus: Of all the countries in the world, only three still use the archaic Imperial system of weights and measures: Liberia. Myanmar (a.k.a. €śthe country formerly known as Burma€ť) United States of America. It's surprising how much "secret" adoption of SI has gone on here. Two-liter bottles of Coke. 750-ml bottles of wine. My husband has both metric and English tools in his workshop. And of course we use the same second as the rest of the world. Cindy Hamilton I see. -- Bod |
#40
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Thermometers: What's the Problem with Accuracy?
It's surprising how much "secret" adoption of SI has gone on here. Two-liter bottles of Coke. 750-ml bottles of wine. And we use the same second as the rest of the world. .... it just seems much longer - since the Scary Clown :-) |
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