TDC1000: accuracy issue

rashmi hm

Part Number: TDC1000

Hello scott,

we are getting the flow rate with a accuracy of +/- 20% of the volume of water flowing through the pipe ,the specification of the transducer that we had received is as follows,

Transducer part number : T/R975-US0014L353-01

Thick Resonant Frequency : 975KHz

The specification of pipe that we are mounting the transducer for the flow measurements is as follows,

Inner Diameter : 1.8 cm

Outer diameter : 2.0 cm

pipe material type : CPVC/ PVC

I would like to know that we should use smaller diameter transducer for the pipe specification that i have specified above. And also i attached image file that displays the mounting of transducer on the pipe.Please provide us feedback so that we can work towards getting better accuracy flow rate.

Regards,

Rashmi H M

over 5 years ago

0 Bharat Aravamudhan over 5 years ago

TI__Genius 11015 points

Hello Rashmi,

I have taken notice of your question and will respond in a couple of days.

0 Bharat Aravamudhan over 5 years ago in reply to Bharat Aravamudhan

TI__Genius 11015 points

Rashmi,

Based on the part number that you have provided for the transducer, we find that the transducer has a size of 20mm which is the same as your pipe diameter, you will need a much smaller transducer (preferably < 10mm) to have accurate measurement for a 20mm pipe.

0 rashmi hm over 5 years ago in reply to Bharat Aravamudhan

Intellectual 750 points

Hello Bharat,
Thanks for the reply and i have some more doubts regarding transducer
1) you have suggested that we should try with <10 mm transducer diameter for 20 mm diameter pipe,how can we know about this combination
for different diameter pipe.
2)what are the specifications to select proper transducer in particular for water flow meter.
3)and can you please suggest us the source for the transducer with less than 10 mm diameter.

0 rashmi hm over 5 years ago in reply to rashmi hm

Intellectual 750 points

Hello Bharat,

i need one more clarification regarding <10 mm transducer is i) what is the resonant frequency that we should choose for the transducer with a diameter less than 10mm.

Regards,

Rashmi H M

0 Bharat Aravamudhan over 5 years ago in reply to rashmi hm

TI__Genius 11015 points

Hi Rashmi,

I will get back with responses for your queries with a couple of days.

0 Bharat Aravamudhan over 5 years ago in reply to rashmi hm

TI__Genius 11015 points

Rashmi,

The 10mm is an arbitrary value that was suggested, please note always have a smaller transducer (diameter) than the actual pipe and make sure that the transducers contact against the pipe does not damp its frequency. This is the reason you need a transducer much smaller than your 20mm dia pipe.

As for resonant frequency & other considerations to chose transducer, please refer the "Ultrasonic Sensing for Water Flow Meters and Heat Meters" app note in www.ti.com/.../snia020.pdf

Please refer to table 1 in www.ti.com/.../snaa266a.pdf, it refers some transducer manufacturers wherein you could find a transducer ~10mm dia for your application.

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TDC1000: accuracy issue