What is an Instrument Calibrator?
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- Опубліковано 4 сер 2024
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⌚Timestamps:
00:00 - Intro
00:56 - Why calibrate instruments?
01:31 - Instrument calibrator types
01:34 - 1) Block (dry-well)
01:51 - 2) Fluid bath
02:05 - 3) Pneumatic
03:10 - 4) Signal reference calibrators
04:42 - Source and simulate modes
05:24 - Troubleshooting a 2-wire current loop
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In this video, we’re going to discuss instrument calibrator and show you how the instrument calibrators can be used in the process control industry for calibration and troubleshooting.
If the quantity being measured is not being accurately represented by the measuring instrument, the measuring instrument possibly requires calibration.
Instruments require calibration for many reasons:
- Equipment degrades over time.
- Anytime maintenance is performed on an instrument, it needs to be calibrated.
- Often the range of an instrument is changed thereby requiring calibration.
Let’s look at a few different types of instrument calibrators.
1) Block or dry-well calibrators are used to calibrate temperature probes such as RTDs and Thermocouples. The temperature sensor is placed in the dry-well calibrator. A metal block is heated and held at a precise temperature.
2) A Fluid Bath Calibrator is similar to a dry-well calibrator as the temperature sensor is placed inside. The big difference is the sensor is immersed in a fluid that is heated and held at a precise temperature.
3) Pneumatic Calibrators provide regulated pressure as needed to calibrate, test, or troubleshoot pressure instruments.
A) One of the oldest and most accurate pneumatic calibrators is the Dead Weight Tester (or DWT).
A DWT will likely be found mounted permanently in the instrument shop. The DWT has several Dead Weights that are precisely calibrated in pressure units.
B) Another type of pneumatic calibrator is the Hand Held Aspirator. A scissor-like grip adjusts the output pressure and a digital gauge indicates the pressure readout.
Hand-held aspirators are particularly useful when field testing and calibrating devices such as pressure switches.
4) Signal Reference Calibrators can output a variety of electrical signals. There are many different types of Signal Reference Calibrators available to produce electrical outputs such as voltage, current, ohms, frequency, etc.
Many signal reference calibrators are capable of simulating thermocouples and RTDs as well. This type of calibrator often referred to as a Simulator, can accurately reproduce a sensor output and display that output in the variable units it represents.
Many signal reference calibrators also perform measurement functions similar to a Digital Multimeter.
These multifunction calibrators are very useful. For example, a Thermocouple transmitter can be calibrated across its entire temperature range using the Thermocouple Simulation function of the Calibrator.
The user selects the Thermocouple type on a calibrator and enters the required simulation temperature. The resulting transmitter mA current output is displayed by the measurement function of the calibrator.
As a troubleshooting tool, a multifunction calibrator is invaluable. With a few quick measurements, a Field Tech can determine if a fault is caused by the sensor or the transmitter.
Source and Simulate are 2 terms commonly used by calibrator vendors to describe modes of operation.
- In Source mode, the calibrator generates calibrated signals for testing and calibrating process instruments.
- In Simulate mode, the calibrator replaces or simulates a transmitter in a 2-wire loop configuration. The calibrator can be adjusted to supply known settable test currents.
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You might want to review our other articles:
DP Flow Transmitter Testing and Recalibration realpars.com/calibration
What is Sensor Calibration and Why is it Important? realpars.com/sensor-calibration
What are 2-Wire and 4-Wire Transmitter Output Loops? realpars.com/transmitter-wiring
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#RealPars #instrument #Calibrator
You guys are saving my life. Thank you
In addition to the crystal clear explanation on the topic, you guys provide more links to clarify any doubt. Thanks for sharing your knowledge... it has unlimited value.
That's an amazing compliment, Felix! Many thanks. Happy learning, and always feel free to reach out if you have any questions.
this video remembered me the first realpars videos short but full of information thanks
You're very welcome!
Great video!!
Another great video!
A couple of things to be aware of is:
a) Calibrators need calibration too. For most machinery this isn't a really big deal, until it is. :)
b) One of the best early warning tools is your PID loop. The natural tendency is to blame the PID when it is simply reacting to different inputs then what it was set up for. Whenever you have a previously well-tuned PID loop get unstable, look at your inputs and outputs.
Hi MrWaalkman........ Thanks for your input. Yes indeed...Calibrators need calibration. Another reader Luis Ballestros mentions the terms primary and secondary standards in a comment on this very same video. One can only assume that the calibrator is actually producing 4.0 mA when being asked to do so. Good insight on the PID loop too.
@@realpars As for a current source, I agree. They are dead simple to make, and are basically bullet-proof. With only three parts it's pretty hard to mess up.
Here's my go-to circuit:
www.bristolwatch.com/ccs/LM317.htm
I added a switchable resistor bank where I could select 4, 8, 12, 16, and 20 milliamps on mine. You can get a cheap one these days for less than the cost to build one. That wasn't true when I built mine (otherwise I would have bought one). In any case, it's hard to justify a $800 current source unless you really need it.
I do have a few NIST traceable testers, which I bought for their (presumable) accuracy and not because I'll need/plan to send them back to get them calibrated. Some testers I would, like an RH meter since it is a bit of a demon at the best of times. For the most part regarding on what I work on, close enough is close enough.
Awesome!!! this is I been waiting.. more discussion about instrumentation.. more subscribers to come sir. Keep safe..
Glad to hear that you enjoyed this video course, Amin! Happy learning.
Amazing explanation, i want to buy a calibrator right now! 😂
Perfect videos as always
Thank you!
Thanks for the video, as always very knowledgeable and professional.
Would be great to know which software are you using to draw the animations???
Hi Bogdan,
Thanks for your kind comment!
I am actually not sure about this as this is done by our Graphic and Animation department.
Thank you Sir .
You're very welcome!
Very useful video 👍
Glad to hear that, Ahmad!
Very informative
Glad to hear that!
This channel rocks wished I had it when I was in school
Thanks a lot, Nickalas!
Dear Real Pars. Excellent Explanation! I have a question. Are there automatic calibrators currently for industrial sensors, or any sensor that can auto-calibrate itself?
Hi Hector! Those are great questions. There are sensors that perform certain auto-calibration functions. For example, Honeywell has Auto-Zero, a calibration technique for specific pressure sensors. We can only assume that now that we are in the IoT Revolution, Smart Sensors demand that we pay more attention to the development of Auto calibration and auto-calibrators. Of course one of the primary problems is knowing that calibration is necessary. One can spend hours on the internet reading about this!
@@realpars Ok thank's!
Awesome👍
Thank you!
Dear Sir,
As usual thanks a million times for your amazing explained tutorial,
I've this short question, please
@ 06:10 in the Simulatie Mode, why did you connect the power supply in Series although the calibrator being used in the video is Fluke 754 which has the capability to source & simulate alone without external power supply,
This quest came up as the basics of the tutorial says:
- Sourcing is replacing the transmitter & power supply to check the Passive Receiver which in our case Analog input module,
- Simulate is replacing the transmitter also for checking or calibrating but an Active Receiver which the Analog input module, but why in your simulate process you kindly kept the power supply in the loop,
I do highly appreciate your effort and time in making such useful and very educational videos
Hi @Malik Arthur. Thanks for reaching out, and thank you for your kind words. In Simulate mode, the calibrator replaces the transmitter. By connecting the calibrator in place of the power supply, we are "simulating" the entire loop. So, we can set the current output of the calibrator for any value we want. If we get the results we expect from the PLC, then we know the problem is the transmitter. If we don't get the results we expect from the PLC, then our problem lies somewhere else in the loop. I hope that helps. If not, let me know.
@@realpars
Dear Proff.
Thanks for your professional attitude in handling our enquiries.
I watched the other videos, on your valuable channel, which are related to Source and Simulate Procedures for testing control loop components.
I could now summarize it as simple as this;
In Sourcing mode the calibrator works as power supply and signal regulator to the receiver ( the signal per our calibration desire ).
In Simulating mode the calibrator relays on external power supply and it only regulates and magnitude the signal to the Receiver.
In Source mode the calibrator replaces both the power supply and the transmitter.
In simulate mode the calibrator replaces only the transmitter.
And again i can not thank you enough for your time & effort in preparing such amazing tutorial videos.
I use most of these every damn day at work. Dead weight testers are hilariously analog but are the only tool for the job at times.
Hi Geomar........ I'm sure lots of field tech and engineers out there have interesting dead weight tester stories about when they first saw that monstrosity in the instrument shop.
Is there any recomendation for handheld communicator (HART)? for pressure, flow, temperature. It would be nice if it under $7k
Hi @iammostwanted kun. There are lots of HART communicators available. It's difficult to pick or suggest because there are so many to choose from. As with most test devices, Fluke is a leader of course. And, as they say, you get what you pay for.
@@realpars any suggestion between AMS TREX and Fluke 754? On what i see the fluke 754 is more an all in one device. But others also recomend me with AMS Trex which i dont know what is the pros for that device.
I have a question from a previous video, i hear a lot about self calibrating instruments these days, what are the limitations of self calibrating instruments and will these instruments completely replace manual calibration?
There are certainly pros and cons when it comes to self-calibrating instruments. They are expensive, not easy to repair if they fail, and quite often require tweaking and periodic checks to verify correct performance. Will they completely replace manual calibration? I’m not sure if anyone can answer that question now.
@@realpars thank you, i appreciate your reply.
these videos are great they make you want to buy the product 😂😂
Thank you, Ed! :)
What does RTD stand for
Resistance temperature detector.
Calibration = Correlation. Your instrument calibrator it is actually a Secondary Standard that is certified against a Primary Standard.
This Primary Standard shall be send to the National Standards Bureau Center to be certified; Or it can also send be send to laboratories that
NSB "designates as authorized to carry out this certification."
These laboratories should indicate ( data and written) whether the measurement equipment meets the requirements to act as a primary standard and
the operating conditions.
The laboratories will be issue a certificate with the correct data and such document will be indicate the percentage of deviation regarding with respect to their
NSB standards and if they are within the deviation parameters
The calibration or correlation process is very important to be carried out.
Because if it is not done correctly can severely affect the personal safety of personnel and it can cost a lot money and time to repair the damage.
Other inherent advantage of a good calibration program is that the effectiveness and reliability of the equipment can be monitored and will be determined when is best time be be replace such equipment.
Calibration Program has Three Stages.
1.- Shall send the Primary Standard to NSB or its assigned laboratories, for correlation and certification again the NSB standards
The Primary Standard shall never and ever be used as a Secondary Standard
2.- Correlate ( without forgetting the operating conditions with which the Primary Standard was measured) the data of Primary Standard with the readings of Secondary Standard to see if they can be used as Secondary Standard.
3.- Correlate the measurements an equipment that is subject to calibration vs Secondary Standard ( Instrument Calibrator) readings and determine if the equipment parameters need adjusted.
Hello Luis C Ballesteros...... Thanks for your input! We couldn't have said it better ourselves. We can't know for sure if our calibrator is actually producing 4.0 mA unless it has been recently certified to do so.
Well.... please get the words straight.... adjustment is not calibrating, these are two different procedures.... but anyway nice Video .... unfortunately these task becomes more difficult with io link or any other databus
Hiya foxtrot....... Thanks for your feedback. Yes, you are correct. We make this statement early in the video..... "Instrument calibration is an adjustment or a series of adjustments performed on an instrument to ensure that the instrument readings accurately represent the quantity being measured.". We could have added that once that has been accomplished, the instrument is calibrated.
Why aren't there subtitles in Italian? That's a shame! You should put them to raise the level of your profile
Thank you, Pino. At the moment we only provide English subtitles. Hopefully, in the future we can add a variety of languages to our subtitle options.
Thanks for your comment!
I love your teaching but you're kind of too fast.thank you
Thank you very much!