Back pressure problem in centrifugal pump

[jarumz]

Currently, i'm trying to design a physiological flow generator to mimic the blood flow. The system is similar to the picture I attached.

However, I'm having problem in choosing the suitable steady pump for the system, as I can't use gear pump (it has high haemolysis potential - damage the blood cells), I also can't use piston pump (it won't create a fully steady flow), . I'm thinking of using centrifugal pump as the steady pump, but the steady flow produced by the centrifugal pump will alter by the back pressure of the system.

Is using back pressure valve a good solution?
Is using axial pump a better option?

I'm in desperate for advice, any advice will be great

Thank you very much ...

 

[itdepends]

Not sure what your trying to do- but rather than a separate pump and piston- can't you use a diaphragm pump instead. You can adjust the stroke length and time if you get the right type- effectively simulating heart rate and size?

 

[Cheddarcaveman]

http://www.medtronic.com/cardsurgery/arrested_heart/centrifugal_pump.html

Have a look at this page. It looks like a centrifugal pump and obviously works.
As a matter of interest, why do you have to "re-invent" a blood pump? There are dozens of them out there.

 

[hydromech]

Is the heart not a pump..?

Does it not pump blood..?

A heart is very similar to a diaphragm pump.

Seems the obvious way to go.

Adrian

 

[jarumz]

First of all, thank you very much for the replies

I don't think I can use diaphragm pump as an option, as what i know, diaphragm pump will only allow one direction of flow. Meanwhile, it is essential for the system to be able to create a back flow, to cause the valve in the measurement section to close.

In overview, steady pump in the system should provide a continuity of the system, while the piston pump will be a flow modulator, to create a blood flow waveform, which includes a back flow.

I'm trying to design an experimental system that can mimic a wide range of blood flow waveforms (aortic flow, capillary flow, veinous flow, etc). While the blood pumps I found is mostly for surgical purposes, such as the centrifugal or axial pump on its own, and they can't produce back flow on its own.

I don't really understand how the 'back pressure valve' works, does it enable us to lower the back pressure acting on the pump?

 

[stanier]

Try a peristaltic pump

Geoffrey D Stone FIMechE C.Eng;FIEAust CP Eng

http://www.waterhammer.bigblog.com.au

 

[jarumz]

I tried to look in the peristaltic, and i found out that peristaltic won't be able to produce a fully steady flow, which cause by the relaxation of the tubing at the end of the rotation wheel, and also its wear and tear limitation on the tubing.

 

[rcooper]

I once saw a patent for a diaphragm pump designed to produce constant flow rate. The patent should have expire by now as it was quite old. It comprised a specially shaped cam with three rockers 120 degrees apart. Each rocker moved the diaphragm on one of three diaphragm pumps. By making the cam the correct shape, it was possible to produce a constant flow rate.

It was a while ago I saw this. It may have been four rockers/pumps. With a bit of work it shouldn't be too difficult to work out the shape of the cam to produce this pump. The original patent was for a constant flow rate dosing pumps and was owned by the forbearers to Paterson Candy Ltd (now part of Black and Veatch in the UK) but they stopped manufacturing anything ages ago.

 

[FILGUEIRAS]

Try a progressive cavity pump. It's a positive displacement device, and I remember I've saw once a fabricant claiming that it would be able to pump a tomato - without smashing it.

 

[FILGUEIRAS]

You may also use the pump used in haemodialysis - they pump blood, I think

 

[rcooper]

The pump we are after is a pulse free positive displacement pump which generates low shear in the fluid. Without doing anything novel, the closest thing on the market to a pulse free PD pump I can think of is a progressive cavity pump, but these have pulses. To get truly pulse free you are looking for something a bit special.

 

[hydtools]

How much pressure do you need?

A reservoir will deliver pulse-free flow. Have a pump keep a reservoir at some level. Maybe a pressurized tank to deliver the pressure you need. That sounds like an accumulator. An accumulator will smooth pump pulses.

Ted

 

[chief]

Consider a Pitot tube pump. They give a steady pressure delivery with low flow, but the size you are looking for may not be óff the shelf'available.

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