Hydraulic or Pneumatic Cylinder as a Liquid Pump? 1

[Helepolis]

Hi all,

I need to replace a plastic 3ml syringe on an experimental setup to something more robust.
The syringe acts as a miniature pump, and the pumping action is at a very high frequancy which results in leakeges of air in to the system.
The substance that the syringe is pumping is water mixed with glicerol.

I was wondering if a small pneumatic cylinder will do the job, or I have to find an hydraulic cylinder that can handle liquids less viscous than oil?
The reason I'm asking is that I have little experience with hydraulic and pneumatic cylinders.

 

[Jboggs]

Go to a company that makes pumps for that purpose! There are several different companies that make pumps of all types (rotary, piston, diaphragm, rolling, etc.) specifically for laboratory operations and for all types of liquid media.

 

[PNachtwey]

This application is similar on a much bigger scale

http://www.machinedesign.com/hydraulics/electrohydraulics-drives-engine-research

There were two diaphragm pumps pumping fuel into a diesel engine. There were two hydraulic cylinder pushing the diaphragm pumps. The goal was to keep the pressure constant. The problem was that the hydraulic designer screwed it all up and didn't consider many things.
To keep the pressure constant one pump had to be going forward as the other was retracting. It was a little trickier than that because the fuel compressed so much. The pumps had to move forward about 30% of stroke because the fuel had to be pressurized to 40,000+ psi before the check valve would open up. This meant that there should have been times when both pumps were moving forward but the hydraulic designer didn't allow the pump to retract fast enough so there was some ripple.
Just scale this down to milliliters.

The OP said nothing about keeping the pressure or flow constant. Is this important?

5HZ is nothing.




Peter Nachtwey
Delta Computer Systems

http://www.deltamotion.com

http://forum.deltamotion.com/