Print page

Print page

Flow Meters: What is the appropriate length of reducer and expander?

Q: I have to install a flow meter size 900mm on a 1,600mm water pipe line. Gravity flow with 5,600 cubic meters/hr flow rate. What will be the effect on the flow profile? Line pressure? What will be the pressure drop? Will it affect/resist flow? Meter length would be around 500mm. Please suggest appropriate length of reducer and expander.

A:

Flow rate – 5,600 cubic meters/hour = 24,656 gallons/minute
Meter Size - 900 mm = 35.43 inches
Pipe Size – 1,600 mm = approx. 63 inches
Meter Length - 500 mm = 19.7 inches
 
What kind of meter is being used? Choices – 36-inch magnetic that is about 20 inches long in a 63-inch pipe?
If it is a magnetic meter and there is gravity flow, my concern would be that the pipe must be kept full (no air in top of the pipe).
If it is a magnetic meter, straight runs and velocity profiles are of little concerns.
My data goes up to about 20,000 gpm in 24-inch pipe.
If it is a magnetic meter, ask the manufacturer about pressure drops, etc.
If it isn't a magnetic meter, what is it and then ask the manufacturer.

Here are more of the latest questions on: Instrumentation and Control

Can you explain a split range controller?
Regarding split range controller:

1. Is it normal to have a control valve with two different sizes?
2. Why use a split range controller and where can we it?
3. My application: I am planning to use at outlet of condenser. The outlet will have condensate liquid and non-condensate vapor. Will it work here?

Can you explain linearity and accuracy of flowmeters?
I am confused on linearity and accuracy of flowmeters such as oval meters. In some references they are mentioned as the same but in some others they are not the same. Should I only rely on linearity for selection for measuring custody transfer or another flowmeter characteristic?

Can you recommend a flowmeter?
We are going to install a flowmeter for lube oil loading as custody transfer. The flowrate may alter between 140-280 CMH (two-speed motor) having viscosity 150cSt at 40C. Simple installation and setting up on the line and reasonable cost as well as pressure drop are preferred. The pump can generate 8barg pressure. What would be the recommended flow measuring type to support the requested service?

Where should I install the control valve on the hot oil line?
I am going to use hot oil for heating a process in a jacketed vessel and I am going to make a control loop for controlling the vessel content. The hot oil enters at the bottom of the jacket and exits from the top. The control elements are RTD, controller, and control valve. My question: Where should I install the control valve on the hot oil line? Is it up stream or down stream of the vessel?

Why is there a discrepancy of solids at sampling points?
Ours is a fertilizer industry and within the premises we transfer phosphoric acid from the phosphoric acid production facility to the fertilizer production facility. The distance of the pipeline might be around 400m but the difference in issue and receipts generally comes out to be 100s of tons per day. Can you tell me what could be the possible problem? Other info required:

1. Phosphoric acid has around 5% solids
2. Sampling point in phosphoric acid tank is at the bottom
3. Sampling point in the fertilizer plant is at a higher level(25 ft) and is preceded by a lot of bends.

Back to Ask the Experts