Pitot Tube & DP Meter Selection for Small Scale Processes

In summary, the conversation discusses the need for a pitot tube and differential pressure transmitter for a small scale process. The question is raised about whether there is a minimum flowrate for these instruments or only a maximum allowable flowrate. The conversation also includes links to manuals discussing the properties and selection of pitot tubes.
  • #1
davidgrant23
22
0
Hi there,

I have been in contact with a manufacturer as I require both a pitot tube and a differential pressure transmitter for my process. Both will be used in a small scale process (around 10 l/min).

I want to ask if it is possible that a flowrate can be too small to generate a large enough differential pressure for some DP meters/transmitters. Is there such a thing as a minimum flowrate for pitot tubes and DP meters, or is there only a maximum allowable flowrate?


Thanks,
David
 
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  • #2
Here's one manual that talks about minimum rates:

http://www.unitedsensorcorp.com/pitot-properties.html

and here's Omega's guide that describes how to select pitot tubes:

http://www.omega.com/Green/pdf/PITOT_SELECTION_REF.pdf

and here's another more descriptive manual:

http://www05.abb.com/global/scot/scot203.nsf/veritydisplay/515d2522afafd358c12575a9002bd35b/$file/pb_torbar_en_%20issue%201.pdf [Broken]
 
Last edited by a moderator:

1. What is a Pitot Tube and DP Meter, and how do they work?

A Pitot Tube is a device used for measuring fluid flow velocity, while a DP Meter (Differential Pressure Meter) is used to measure the difference in pressure between two points. Both instruments work on the principle of Bernoulli's equation, where the velocity and pressure of a fluid are inversely related. The Pitot Tube measures the stagnation pressure, which is the sum of the static and dynamic pressures, while the DP Meter measures the difference between the static and total pressures.

2. How do you select the right Pitot Tube and DP Meter for small scale processes?

When selecting a Pitot Tube and DP Meter for small scale processes, it is essential to consider the fluid properties, such as density, viscosity, and temperature, as well as the flow rate and pressure range. The size and shape of the pipe or duct where the instruments will be installed should also be taken into account. Additionally, the accuracy and repeatability requirements of the process should be considered when selecting the appropriate instrument.

3. What are the advantages and limitations of using a Pitot Tube and DP Meter for small scale processes?

The main advantage of using a Pitot Tube and DP Meter for small scale processes is their simplicity and relatively low cost compared to other flow measurement methods. They also have a wide range of applications and can measure both gases and liquids. However, their accuracy can be affected by changes in fluid properties and flow conditions, and they may require frequent calibration to maintain accuracy. Additionally, the installation of these instruments can be challenging in some applications.

4. Can a Pitot Tube and DP Meter be used for all types of fluids?

While Pitot Tubes and DP Meters can measure various fluids, including gases, liquids, and steam, they are typically best suited for clean, low-viscosity fluids. High-viscosity fluids, as well as those with high solids content, can cause blockages and affect the accuracy of the measurement. In these cases, alternative flow measurement methods may be more suitable.

5. How often should a Pitot Tube and DP Meter be calibrated?

It is recommended to calibrate Pitot Tubes and DP Meters at least once a year to maintain accuracy. However, the frequency of calibration may need to be increased if there are significant changes in the process conditions or if the instruments are used in critical applications where accuracy is crucial. It is also essential to follow the manufacturer's recommendations for calibration and maintenance to ensure reliable and accurate measurements.

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