Product distribution - Tubing Lines
Product distribution - Tubing Lines
(OP)
Hello everyone,
I am a junior engineer. I am now working on the design of a dosing system for small quantities using tubing lines and very specific equipment (flowmeters, valves...).
Due to the low flow and configuration (30m length - 10 m up), the pressure drop that I calculate will be of aprox. 6 bars (considering the flow meter pressure drop).
My question is: With an adequate pump (6bar+)... do you think this installation could work?
I am not familiar with tubing (I always work with pipes). I know this is a very general (and silly) question but I have the feeling I am missing something.
Tubing lines are can withstand very high pressures, so I assume they are normally used on high pressurized systems.
The product is no viscuous and has a density of 850kg/m3.
Thank you very much for your support.
I am a junior engineer. I am now working on the design of a dosing system for small quantities using tubing lines and very specific equipment (flowmeters, valves...).
Due to the low flow and configuration (30m length - 10 m up), the pressure drop that I calculate will be of aprox. 6 bars (considering the flow meter pressure drop).
My question is: With an adequate pump (6bar+)... do you think this installation could work?
I am not familiar with tubing (I always work with pipes). I know this is a very general (and silly) question but I have the feeling I am missing something.
Tubing lines are can withstand very high pressures, so I assume they are normally used on high pressurized systems.
The product is no viscuous and has a density of 850kg/m3.
Thank you very much for your support.





RE: Product distribution - Tubing Lines
RE: Product distribution - Tubing Lines
People are usually surprised when they find out that 1/4" x 0.022" and 3/8" x 0.035" have a working rating of over 3600psi.
Many dosing systems do not use valves and flow meters, but rather close-loop controlled metering pumps. Look at your system options.
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P.E. Metallurgy, Plymouth Tube
RE: Product distribution - Tubing Lines
In my case I am surprised for the low pressure drop, seeing that tubing lines have such a high pressure rating.
I checked some metering pumps but the accuracy is not as good a coriolis flowmeter.
Thanks again!
RE: Product distribution - Tubing Lines
I think of people like ProMinent, Lewa, and mRoy.
These pumps have better turn-down ratios than coriolis meters, usually 1000:1 with constant accuracy.
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P.E. Metallurgy, Plymouth Tube
RE: Product distribution - Tubing Lines
I have been checking some from Prominent and Lewa pumps and accuracies are aprox 1%... with the accuracy of our selected flowmeter is 0.3%.
Even though our application is in production (not labo), the quantities used are very low (from 150g) and small deviations could have a significant effect on the final product.
I will continue checking, it is worth having a look.
Thanks a lot for your advise.
RE: Product distribution - Tubing Lines
What you really want is a syringe pump:
http://www.teledyneisco.com/pumps/reactant-feed
Pressure drop is a matter of flow, density and linesize. If the pressure drop is too high, you simply increase the linesize, the same as you would in piping. The difference is that the surface area to volume ratio is very small- you will find it difficult to achieve high Reynolds numbers in these lines, so the velocity "rules of thumb" used for pipe sizing go into the toilet as useless once you're into tubing. Instead, you use a parameter such as differential pressure per 100 ft of line length etc.
RE: Product distribution - Tubing Lines
I think those types of pumps cannot be an option on our case. They are difficult to operate with and we need a complete close system.
I have one more little question... I have to select the tubbing size for the system and due to the low flow I also have low flow velocities (0.6m/s or 0.3m/s).. could that be a problem also considering the distribution circuit(30m length - 10 m up)? (of course, also considering enough pump pressure)
Thanks again.
RE: Product distribution - Tubing Lines
Will laminar flow be an issue for your liquid or transport dynamics (as moltenmetal pointed out)? If some residual liquid remains stagnant for a period of time, is that okay or do you need to provide low point drains and purge gas?
RE: Product distribution - Tubing Lines
You need a flow loop for the long lengths of tubing so that the line is always filled up to the point of use and constantly flushed to remove bubbles. At the point of use you place the metering pump. And right at the injection point you place a check valve to prevent dribbling flow after the metering pump has stopped.
http://fluidmetering.com/
RE: Product distribution - Tubing Lines
Low flowrates result in low velocities. Low velocities are not a problem as long as you are not trying to suspend particles in a liquid, i.e. pumping a fast-settling slury.