Process Calibrator Reccomendations? - Page 1
Forum section: electronics / testgear

author: Tech_Monkey
author_rank: Contributor
timestamp: June 14, 2023, 10:05:31 pm
content: Before I ask my question....does anyone else here experience how hard it is to express to management underlying root cause electrical issues??I need a good process calibrator for some heat controllers that use J and K type thermocouples. I like the fluke multipurpose (726) but its 5 grand US. Can anyone make a suggestion on something thats as good without the price tag? cant spend that much on fluke for the aforementioned management problems....

author: TimFox
author_rank: Super Contributor
timestamp: June 14, 2023, 10:39:40 pm
content: Do you own a sufficiently well-calibrated and sensitive voltmeter?The thermal EMFs for J and K thermocouples are tabulated.You need to buy a simple ice-point reference, and a cheap one can be made with a styrofoam cup, distilled water, and small ice cubes.My old Keithley thermocouple meter had details for that junction construction.This manual is for a similar instrument, and has ice junction construction in section 4.2.https://assets.omega.com/manuals/M0618.pdfThe reason for the ice junction is to connect your two metals to two copper wires to avoid thermal errors at the voltmeter.

author: Tech_Monkey
author_rank: Contributor
timestamp: June 14, 2023, 11:06:39 pm
content: I use a fluke 289 for all my voltage metering issues. im not trying to test the thermocouples accuracy, i'm trying to test the controllers calibration. I dont think I follow how your advice helps me.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: June 15, 2023, 12:56:09 am
content: 1. By "test the controllers calibration" do you mean what the controller reads from the thermocouple? Its 4-20mA output? Something else? Those terms have both general definitions and very specific definitions depending on the industry they are being used in.2. Google "process calibrator" and a few things show up. I took a quick look at the Uni-T UT725. Perhaps something like that is acceptable. Note: you get what you pay for with this kind of equipment.However, I suspect the real problem, as you state, is how to talk to Management about this kind of thing. A few questions:3. Is the organization financially stressed?4. What kind of organization is it? Sales? Service? Manufacturing? Engineering? Other?5. Is mechanical engineering the educational background of Management?6. Is accounting the educational background of Management?

author: J-R
author_rank: Super Contributor
timestamp: June 15, 2023, 12:57:37 am
content: I picked up the Ronan X88 some months back and it's an interesting older device that may be an option for you. You may have to search and wait a bit to find one for a reasonable price.https://ronan.com/wp-content/uploads/2019/09/X88_brochure.pdfhttps://www.ronansystems.com/assets/docs/X88_IOM.pdf

author: BillyO
author_rank: Super Contributor
timestamp: June 15, 2023, 03:22:35 am
content: Quote from: Tomorokoshi on June 15, 2023, 12:56:09 amThis is the best response I've seen in some time. A bit brutal, but direct and to the point.If your company really needs the accuracy, precision and traceability of the 5-10 grand instrument there is, unfortunately, no $200 Chinese drop-in replacement.How precise do you need to be? +/- 0.0001 C? More accurate? +/- 10C?What are your requirements as to target and tolerance? Also, what's at stake if you are wrong? Lives or refunds?

author: BillyO
author_rank: Super Contributor
timestamp: June 15, 2023, 03:24:01 am
content: Quote from: Tech_Monkey on June 14, 2023, 10:05:31 pmPar for the course.

author: J-R
author_rank: Super Contributor
timestamp: June 15, 2023, 05:06:25 am
content: Fluke 726 is $4500 from Amazon, 725 is a bit less at $3600.726 is about $2k used on eBay.

author: TimFox
author_rank: Super Contributor
timestamp: June 15, 2023, 01:46:13 pm
content: Quote from: Tech_Monkey on June 14, 2023, 11:06:39 pmSecton 4.2 of my citation shows how to calibrate a meter that measures a thermocouple voltage, using a voltage source and ice-point junction.It is NOT a method to calibrate the thermocouple itself.I used that procedure to calibrate a thermocouple meter without needing a variable temperature, using a measured voltage into the circuit (copper wires) and inserting the thermocouple wires into the meter.I started with a commercial thermocouple (with appropriate connector), cutting the junction and using the two dissimilar wires in the circuit shown in section 4.2.It's a nuisance to develop a known temperature of 1000oC on the bench, but a type J thermocouple in the circuit I cited needs 57.953 mV from the external voltage supply (measured on a normal voltmeter) to give the same results in the thermocouple meter.I assume the expensive calibrators do essentially the same thing, although they do not use frozen distilled water for the ice-point junction.Tables of thermocouple emfs for different metal combinations are readily available, e.g.https://www.thermocoupleinfo.com/thermocouple-reference-tables.htmand "Rubber Bibles" (Handbook of Chemistry and Physics, formerly published by the Chemical Rubber Company, now CRC)https://hbcp.chemnetbase.com/faces/contents/ContentsSearch.xhtml;jsessionid=8E86BDA9072F1211BDD5A2DAF5F3F562

author: porter
author_rank: Regular Contributor
timestamp: June 15, 2023, 02:11:04 pm
content: apropos?Extechhttps://www.flir.com/browse/professional-tools/calibration-tools/calibrators/

author: Tech_Monkey
author_rank: Contributor
timestamp: June 15, 2023, 03:32:18 pm
content: Quote from: Tomorokoshi on June 15, 2023, 12:56:09 am1. I just need to simulate the thermoelectic voltage of a thermocouple. The charts are online with the correlation of voltage to temperature. (roughly -10 to 30 millivolts) So I'm looking for a certified device to simulate those voltages and ensure that the temperature shown on the display matches what the thermocouple input is. We have some situations where our machines are having to run hotter than expected on the controls. The problem is either ground looping, or lack of noise immunity in the controllers. I believe the issue is with the grid, management believes its the controllers so frankly I'm about to spend 5k to prove them wrong. (there is also harmonics issues and low power factor issues involved here. this whole grid is just a mess frankly)2 I would like the equipment we buy to be good for the long term, calibrated, certified, and able to grow with a rapidly growing company.3 no and thats what annoys me more than anything.4 heavily engineering reliant manufacturing.5 lol6. lol x2.

author: TimFox
author_rank: Super Contributor
timestamp: June 15, 2023, 03:38:41 pm
content: The method I suggested is calibrated from first principles.It may be cumbersome and labor-intensive, but apparently you can't get enough budget to purchase the faster, higher-cost, digitally controlled calibration equipment.Perhaps your boss can hire, as a summer intern, a nephew who studied high-school physics and can read instructions to do it at an acceptable cost?

author: Tech_Monkey
author_rank: Contributor
timestamp: June 15, 2023, 03:49:57 pm
content: idk why i didnt think about fleabay. Thanks.

author: RAPo
author_rank: Super Contributor
timestamp: June 15, 2023, 03:52:55 pm
content: I use The service of.About 250 euro on Ali.

author: Tech_Monkey
author_rank: Contributor
timestamp: June 15, 2023, 03:54:15 pm
content: Quote from: TimFox on June 15, 2023, 01:46:13 pmI understand what youre saying. But thats not really going to work for the type of tests i need to run across a range of loads and power quality situations. Process calibrator makes it much simpler. I found one for 1800 i think I can get. so no worries. thanks for your input

author: TimFox
author_rank: Super Contributor
timestamp: June 15, 2023, 04:22:36 pm
content: You can invert the measurement I suggested to check the calibration on your reasonably-priced calibrator against a physical ice-point and a calibrated voltmeter.

author: J-R
author_rank: Super Contributor
timestamp: June 15, 2023, 05:03:09 pm
content: Extech PRC30 seems to be an interesting budget option, $850 with NIST certificate. They are in stock.

author: TimFox
author_rank: Super Contributor
timestamp: June 15, 2023, 05:53:08 pm
content: Note that for my J example at 1000oC, the thermal emf has a slope of 0.06 mV/K, or 0.1% of value per degree.This is useful to determine what voltmeter accuracy is required either for calibrating the thermocouple meter, or the inverse circuit for checking the calibration of the thermocouple-simulating calibrator.

author: rvalente
author_rank: Frequent Contributor
timestamp: June 15, 2023, 09:42:44 pm
content: Presys:https://www.presys.com.br/en

author: jchw4
author_rank: Regular Contributor
timestamp: June 16, 2023, 09:12:49 am
content: There are also Omega calibrators:https://www.omega.com/en-us/calibration/temperature-calibrators/c/handheld-calibratorsI own the simplest CL3515R and it's pretty good. They still sell it and offer support and recalibration.But there are certainly better / newer models.Upd: they have multifunction calibrators as wellhttps://www.omega.com/en-us/calibration/c/multifunction-calibrationbut I have no experience with them.

author: tszaboo
author_rank: Super Contributor
timestamp: June 16, 2023, 09:23:33 am
content: Quote from: Tech_Monkey on June 14, 2023, 10:05:31 pmWhen I had issues about equipment calibration, I turned to the quality management of my company. We raised it as a Nonconformity issue for ISO9001, then everything got calibrated. But yeah, those Fluke units are expensive for what they do.

author: armandine2
author_rank: Frequent Contributor
timestamp: June 16, 2023, 10:45:55 am
content: RS Pro 133 - sources and measures thermocouples

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: June 16, 2023, 03:15:07 pm
content: How about a Fluke 787 process meter with a precision 10 ohm, or less, resistor across the outputs. You can simulate the TC voltage to a reasonable accuracy and the 787 is also a great all around multimeter otherwise. It’s still a bit pricey though at around $1000. BTW I’ve done just this with my 787.