DP Flow Transmitter Testing and Recalibration

▶ C’mon over to where you can learn PLC programming faster and easier than you ever thought possible! ============================= ▶ Check out the full blog post over at ============================= In the first video of this 2-part series, we showed you how a Differential Pressure Transmitter is used to measure the 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 ( What is Sensor Calibration and Why is it Important? ( 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. ============================= Missed our most recent videos? Watch them here: ============================= To stay up to date with our last videos and more lessons, make sure to subscribe to this YouTube channel: ============================= TWEET THIS VIDEO ============================= Follow us on Facebook: Follow us on Twitter: Follow us on LinkedIn Follow us on Instagram #Calibration #RealPars #PLC

33 bình luận cho “DP Flow Transmitter Testing and Recalibration

  1. 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").

  2. 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?

  3. 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.

  4. 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.

  5. 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.

  6. 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.

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