DP Flow Transmitter Testing and Recalibration

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▶ Check out the full blog post over at
realpars.com/calibration/
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In the first video of this 2-part series, we showed you how a Differential Pressure Transmitter is used to measure the flow rate. (realpars.com/flow-rate/)
This second part of our series will take you through the process of checking the output accuracy of a differential pressure flow transmitter and show you how to recalibrate it if necessary.
If you haven’t already done so, you might want to review 2 of our other videos:
Differential Pressure Transmitter Explained (realpars.com/differential-pre...)
What is Sensor Calibration and Why is it Important? (realpars.com/sensor-calibration/)
The transmitter must be removed from service before any checks or calibration can be performed. Let’s go through the following steps:
- Close the Low-Pressure Block Valve
- Open the Equalizing Valve
- Close the High-Pressure Block Valve
The first thing we need is a calibration chart or table.
The table is important from a calibration perspective as it indicates what we need to apply to the transmitter, and what the expected current output will be.
Calibration Setup:
The scissor-type hand pump with a digital pressure readout is connected to the high-pressure side of the transmitter.
There are several different types of pressure sources used in the industry.
Note that the low-pressure side of the transmitter is vented to the atmosphere.
A digital multimeter set to measure current is connected in series with the transmitter and the 24-volt power supply.
First of all, we’re going to check to see if the transmitter needs to be adjusted.
We begin by applying the desired pressure input values from the calibration table to the high input on the flow transmitter and record the output current measured for each input value.
If the output currents measured are outside of the acceptable ranges as established by your company, then the transmitter must be recalibrated using the Zero/Span adjustments.
We perform the actual calibration using the Zero/Span adjustments on the transmitter
Let’s return the transmitter to service now that it’s been calibrated.
- Begin with all valves closed
- Open the equalizing valve
- Open the High-Pressure Block Valve
- Close the equalizing valve
- Open the Low-Pressure Block Valve
Here is a review of what we discussed in the video:
- Before calibration, a transmitter must be removed from service by closing the Low-Pressure Block Valve first, then opening the Equalizing Valve second, and finally closing the High-Pressure Block Valve.
- Checking and calibrating the transmitter is completed by using values found in a Calibration Table or Chart kept onsite. The Zero/Span adjustments are used to obtain a specific current output range for a 0% and a 100% differential pressure input.
- After calibration, a transmitter is returned to service by opening the Equalizing Valve first, then opening the High-Pressure Block Valve second, followed by closing the equalization valve, and finally opening the Low-Pressure Block Valve.
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realpars.com/flow-rate/
realpars.com/wireless-communi...
realpars.com/vba/
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#Calibration #RealPars #PLC

[@realpars]

You can add a subtitle in your language to this video. Learn how: support.google.com/youtube/answer/6054623?hl=en

[@agoniaXdunya]

Big ups!

[@ricardogarcia3900]

Excellent !. I will try ...

[@gunnerjonah7183]

I dont mean to be so off topic but does anyone know a way to log back into an Instagram account? I somehow lost my account password. I love any tips you can offer me.

[@tateemmett3846]

@Gunner Jonah Instablaster =)

[@gunnerjonah7183]

@Tate Emmett I really appreciate your reply. I got to the site through google and Im waiting for the hacking stuff now. Seems to take quite some time so I will reply here later with my results.

[@yassershubber6193]

Realpars no words can express our gratitude and appreciation for you and the method employed to simplify instrumentation as you do, hats off

[@realpars]

Thanks for your support, Yasser! That is amazing to hear.

[@MrWaalkman]

One of the best descriptions of this process that I have seen. Truth be told, calibration is usually either skipped entirely, left to the engineer to fudge in the code, or farmed out to a third party to be done. But it's easy enough that it need not be. Excellent work!

[@realpars]

Thanks a lot for sharing that with us!

[@richmond4884]

I m always watching every video you have and always reviewing it for my work

[@realpars]

Happy to hear that, Richmond! Great to know that our course videos are beneficial to you! Feel free to contact us if you have any questions along the way. Happy learning!

[@reshmaravikumar8092]

I am also interested in your videos. I daily watch your videos. Best and simple explanations.. Can I know if ladies have any chances after llcompleting automation plc course

[@ganagamvrksantosh5725]

It was a great gesture from REALPARS for teaching us. I am following ur videos regularly. Can give guidance on designing side

[@realpars]

You're more than welcome, we're happy to hear that you are enjoying our course videos! Happy learning!

[@maruthanilam2448]

Sir. You are great. God bless you.very very useful videos for me and others.

[@realpars]

Thanks for your support!

[@cck0728]

Excellent work. What is the purpose of equalising valve? Thanks for your valuable reply.

[@athilaldurry5880]

Excellent videos, many thanks

[@realpars]

Thanks a lot! Happy learning!

[@asadiqbal87]

thanks real pars

[@ramgr6888]

Nice video. Super explaination.

[@realpars]

Glad it was helpful!

[@santiagomachado5174]

I can do a SCADA project thanks to this!!! Thankyou very much!!!

[@realpars]

That's great, Santiago! Happy learning.

[@manuelbolla3322]

Me encantan tus videos. Saludos de Paraguay

[@realpars]

Gracias, Manuel!

[@jnb8918]

Very good video, great explaination. However, it seems the rotating directions to open and close manifold valves are reversed ? Opening is normally counterclockwise and closing is clockwise rotation. I see the reverse in the video, or is it a optical illusion ?

[@realpars]

Thank you for your question. While this might be accurate when considering plumbing fixtures, the scenario could differ when dealing with industrial devices, particularly due to the distinction between left and right-hand threads. The instructor in the video based their demonstration on their experience with a specific device at the time. For accurate installation guidelines, it's always advisable to consult your user's manual. The suitability of the threading may also vary depending on the vibration levels in the device's operating environment. I've included some links that might further aid your understanding on this topic. accu-components.com/us/p/119-left-hand-vs-right-hand-threads-which-is-best#:~:text=A%20left%2Dhanded%20thread%20is,even%20under%20anti%2Dclockwise%20forces. www.mcmaster.com/products/left-hand-threaded-pipe-nipples/

[@nipunmadushan5320]

Superb

[@ramgr6888]

Very excellent explanation. Thanks for your videos. Will support continuosly....keep to create a new video about instruments....

[@realpars]

Thanks a million, we appreciate your support!

[@waqashabib1674]

Very well explanation....

[@realpars]

Thank you!

[@generaltechnologyknowledge5165]

Thanks for sharing

[@realpars]

You're very welcome!

[@ijaL0611]

Thank you sir,, Your vidio very useful..

[@realpars]

Glad to hear that! Happy learning

[@sufiyanalam9801]

Thanks sir

[@UCING007]

Thanks for information..

[@realpars]

You're very welcome!

[@MM-vi9kh]

Great thanks to you RealPars. 6:35 Please, take an example of 75%... I tried, but I got different answer

[@mustafasarhan5133]

Thanks, Very usefull

[@realpars]

Glad it was helpful!

[@ranadipghosh4008]

Many thanks for an excellent instrumentation video. Your explanation method is commendable. Would highly appreciate if the calibration chart and relevant values could be in SI units.

[@realpars]

Thanks for sharing your feedback with us!

[@AbdullahAhmed-vj2vi]

Thanks a lot

[@realpars]

You're very welcome!

[@rajanbhatt5633]

Again good video sir 👌👍. Next topic as AC or DC reply. Thanks

[@realpars]

You're very welcome!

[@keyankeyan1605]

really useful video keep going

[@realpars]

Great to hear that, Keyan! Thanks for sharing.

[@elshad2024]

definetly agree #Keyan

[@AeroDZ]

Fantastic

[@realpars]

Thank you!

[@gg00ddyy]

I hope you could've explained the reason behind the sequence in the manifold safe operating procedure on removing and returning the DP TX in service. But still great videos from Real Pars.

[@realpars]

Hi John, When the transmitter is removed from, or returned to service, the valves are operated in a sequence to ensure that the delicate DP cell membrane is not damaged from excessive pressure.

[@DiogenesNephew]

@@realpars Would this not also be achieved by isolating the high and low side first and then equalizing?

[@muhamadsherko8801]

To avoid connecting the transmitter to the process in one sode i mean if your transmitter conected to hight or low side at different time so it will damage your diafragm because pressure applied to one side of it

[@sarantb8936]

Please make clear the sequence and significance of valve isolation before and after the calibration, more over what will happen if I open the equalizer valve before closing the LP side isolation?

[@ricardogarcia3900]

All your videos are great. Congratulations. Only one bug at 4:57 (DP must be 12.5 in WC).

[@realpars]

Hey Ricardo.....you have a very keen eye! In the animation, we should be showing a current value of 13 mA, not 5mA. If the current flow is 5mA, the DP is indeed 12.5 inWC. Thanks for pointing that out.

[@Meraj.786]

Fᴀɴᴛᴀᴅᴛɪᴄ❤️

[@earlgreen6644]

I really like your video series. I believe your red arrows depicting the manifold valve operations are incorrect in this video. It should be counter-clockwise to open, and clockwise to close ("Lefty Loosey, Righty Tighty").

[@realpars]

Earl, thank you for your comment. Yes, I believe you are correct.

[@paulmichaux7136]

I thought that too

[@tomas8967]

Excellent video, I would just like to know why or based on what steps are performed to leave out of service a differential pressure transmitter?

[@realpars]

Hi @Tomas Morales Perez. Sorry, I'm not sure I understand your question. Are you asking about the reasons why removing from service is performed in that order?

[@mdnezamuddin6219]

tnx

[@syedamaan2797]

love from india

[@G-ALM]

Great video, how ever, while we connect the hand pump and applying the pressure, the equalisation valve shall be opened or closed?

[@realpars]

Hi there, Thank you for your question; it's a great one. However, I want to clarify that the information we provide is meant to illustrate the process rather than serve as an instruction manual for the specific device you'll be working with. Therefore, the best course of action would be to follow the directions outlined in your device's user manual or reach out to the vendor for assistance. We're here to help if you have any further questions or need guidance.

[@G-ALM]

@@realpars Great. Thank you , Sir

[@marlockflein1287]

Hi,I don`t find the app,did you change the main image?,because I can`t find it.

[@realpars]

Hi Marlock, We have recently optimized our learning platform which includes some highly requested features. We are happy to bring you these new improvements which will grant an even better learning experience, as a result we had to decide to no longer support the RealPars App. You can use our webpage to continue watching the video courses.  Hope this helps, and happy learning!

[@eissaa.f7779]

Thanks for your videos! I have a question: why did the 8 mA current output give us (25%)?

[@realpars]

Hi Eissa A. Thanks for your question. Please refer to the calibration table at 02:50 of the video. The actual differential pressure is 50 inches WC which is 25% of the differential pressure range. So, 25% of the 4 to 20 mA output range is 8 mA. I hope that helps! If not, don't hesitate to reach out again.

[@eissaa.f7779]

@@realpars oh I missed that! yeah that makes sense now. Thank you for your help

[@muhamadsherko8801]

hellow everybody please I ve a question at the calibration , my quastion is that if we has an instrument like flow transmitter and after teasting we find out that the out put current is corsponding to the input at the zero input and full input for example transmitter which has input range from 0 to 100 gpm after teasting we got 4 mA from 0 gpm and 20 mA at 100gpm but when we cheach the instrument in 50 mA it does not produce 12mA it produce 13.4mA so how to calibrate this ?

[@realpars]

Thank you for your inquiry. Your question is quite intriguing; however, it's important to note that our videos primarily serve as foundational learning resources for understanding engineering concepts in the industry. They are not intended to replace the manufacturer's manual for your specific device. I recommend thoroughly reviewing your user and operator's manual for your device as a first step. This manual should provide detailed information tailored to your device's specifications and functionality. In the event that your issue persists after consulting the manual, I strongly advise reaching out to the manufacturer of your device for further guidance and assistance. They are the experts in their product and can offer specialized support to address your specific concerns. Before contacting the manufacturer, it's also worth checking all your wiring connections to ensure they are secure and free from any electrical interference. Electrical noise can sometimes disrupt the signal from your transmitter, and this aspect is occasionally overlooked. Ensuring correct grounding is in place can also make a significant difference in addressing such issues effectively. We appreciate your commitment to learning, and we hope you find the solution to your challenge. Happy learning from RealPars!

[@MM-vi9kh]

During calibration, should equalizer be open or close?

[@realpars]

The Equalizer valve needs to be closed during calibration.

[@natasciacarboni886]

I think...the real value of current output at 50% of flux is 12 mA because : (20 - 4)= 16...the half is 8 mA that should be added to 4 mA. The real value of current output is certainly 12 mA. Many thanks to your videos.Little imprecisions give us way to open own mind. I'm sorry for my bad english.

[@realpars]

Hi Natascia! As you say, we want the current output to the PLC to be 12 mA at 50% flow. Unfortunately the flow transmitter will not give us 12 mA, but gives us a current of 8 mA. If we connect a Square Root Extractor to the flow transmitter, we now get a current output of 12 mA.

[@asadiqbal87]

@@realpars yes u are wright

[@automationadda3706]

Which software are using in animation plz tell me.

[@realpars]

Hi there, I am not sure about this as this is done by our graphic and animation department.

[@denildavis3561]

Where we connect pressure pump port. is it in vent side of manifold valve

[@realpars]

Hi Denil. The pressure pump is connected to the High Pressure (HP) Port. The Low Pressure (LP) Port is left open, or vented to atmosphere.

[@denildavis3561]

@@realpars thank you

[@maruthanilam2448]

Sir. Pls make video for calibration of GWR type level transmitter.

[@realpars]

Hey! Thanks for your comment and your suggestion. I will pass this on to our course developers! Thanks for sharing and happy learning!

[@divyangpatluwala7425]

please give some more information about root extractor..Why we use that root extractor method..

[@realpars]

Hi Divyang, Thanks for your comment and topic suggestion. I will happily pass this on to our course developers! Happy learning!

[@senthil51]

In play Store i couldn't find the App

[@realpars]

Hi Senthil, We have recently optimized our learning platform which includes some highly requested features. We are happy to bring you these new improvements which will grant an even better learning experience, as a result we had to decide to no longer support the RealPars App. You can use our webpage to continue watching the video courses.

[@radyajatmikaristananda219]

This procedure same for DP Level Transmitter?

[@realpars]

Thank you for your question! Yes, it is similar. Please refer to the user manual for detailed calibration procedures and instrumentation instructions. Happy learning!

[@RS_83]

Why at 1:20 are you closing first the low pressure block valve? I think you need to open the equalizing valve first, in order to prevent damage to the dp cell. Am i not right?

[@realpars]

The method in the video is correct. First, the low pressure valve is closed, which keeps the current pressure on the low side trapped against the capsule. The output of the transmitter is maintained near the current value. With the low pressure valve closed, the equalizing valve can be opened, so the differential pressure is reduced as the pressure on the low side equalizes to that on the high side. Finally, the high pressure valve is closed. With the equalizing valve still open, the excess pressure can be bled from the capsule to make it safe to remove or calibrate.

[@RS_83]

@@realpars yes, you're right. Thanks!

[@IKENNA369]

​@realpars what if you open the equalizer valve first then close the lp block valve and close the hp block valve.

[@RS_83]

@@IKENNA369 i think pressure from the hp side will go to the lp side. Maybe this will not damage the DP cell itself, but nevertheless it's not the best technique anyway

[@mohammadabdulfattah1867]

Sorry I'm not understand the last equation how 8 ma is converted to 12 ma .....is there a sample equation to calculate that

[@realpars]

Hi Mohammad. The key to these conversions is to remember to keep all units in percentages. The output is equal to the square root of the input because of the square root extractor. An input current of 8 mA is 25% of the 4 - 20 mA range. If we find the square root of 25% (.25) we get 0.5. If we convert to the percentage we get 50%. 50% of the 4 - 20 mA range is 12 mA.

[@paulmichaux7136]

I'm just confused about the direction the arrows are pointing to open and close the valves. I thought turning it to the right would close it and to the left would open it,

[@realpars]

Typically "turn right to close" and "turn left to open" would be proper. Always check the action of any device before operating it to ensure you know the "sense" of the device.

[@paulmichaux7136]

@@realpars thanks! Still an awesome video

[@djaztec97]

Why do you close the valves but open the equalizer in a specific order? I don't get it.

[@realpars]

Hi @John. Thanks for your question. Bottom line, it's about attempting to maintain a close-to-balanced differential pressure across the sensitive diaphragm in the transmitter.

[@PhthaloBlue42]

Why was pressure only applied to the high side?

[@realpars]

Thank you for your inquiry. The hand pump is positioned on the high-pressure side because it connects to where the fluid originates, meaning it's under high pressure. This setup allows us to measure pressure accurately from this side. Essentially, the pump emulates the flow pressure experienced by the sensor. If you're interested in learning more about such devices, I recommend checking out this link to a company that specializes in them. It could offer you further insight into their functionality and applications. www.omega.com/en-us/ Happy learning!

[@dedyapria1177]

At 01:20 why don't you close the high pressure block valve first instead?

[@realpars]

To ensure that pressure is equalized on both sides of the DP cell.

[@dedyapria1177]

@@realpars what if I close the high pressure block valve first then open equalize valve and finally close the low pressure block valve?

[@eepower]

Can u plz add a link to your app.

[@realpars]

Thanks for your comment! We have recently optimized our learning platform which includes some highly requested features. We are happy to bring you these new improvements which will grant an even better learning experience, as a result we had to decide to no longer support the RealPars App. You can use our webpage to continue watching the video courses.

[@jasonsprigg6722]

This is a bit deceiving. You are not calibrating the flow meter with this set up, you are ONLY calibrating the pressure transmitter section of the flow meter. If the orifice plate or other components have issues this calibration will not help.

[@realpars]

Hi Jason, you are correct. Any changes such as a different orifice plate would change our calibration values. That's why we've specified that we are calibrating the differential transmitter only using the given DP values and flow rates.