Metering pump

[Steve_88]

Hi,

I'm looking for a cheapo metering pump, I figured I would provide my own motor and controller, maybe a stepper motor..........

need the flow to be smooth as possible (no pulses).

Accuracy of rate, maybe a few percent

I want to pump some mineral oil at 95 F at a rate of around 0.1 liter/minute

Thanks for any idea's, as you can see I don't know half the questions yet

Steve

[skimask]

Hi,
I'm looking for a cheapo metering pump, I figured I would provide my own motor and controller, maybe a stepper motor..........
need the flow to be smooth as possible (no pulses).
Accuracy of rate, maybe a few percent
I want to pump some mineral oil at 95 F at a rate of around 0.1 liter/minute
Thanks for any idea's, as you can see I don't know half the questions yet
Steve

I've got no idea if this will work, but here goes...
In the model airplane world, you've got this thing called a 'Dave Brown 6 Shooter'.
Basically, it's a rubber hose sitting in a round channel. A few wheels mounted on a round disk come around and compress this hose (with a gap in between the wheels), pushing the fluid inside along. Shouldn't be that hard to run it for a bit and calculate what each 'turn' of the wheel will dish out, and it should be consistent. It might pulse a bit, maybe put a small accumulator tank on the outlet side.
Do a search on 'Dave Brown 6 Shooter' and you'll see what I'm talking about.

[BrianT]

A looped tube, typically wrapping a bit more than 180 degrees and engaged by two roller bearing 'squeegees', is a very repeatable and reliable pumping system for medium temperatures and low pressures. Provided the discharge pressure is constant, typically ambient atmospheric, the volume delivered is very constant. It's called a peristaltic pump and is widely used in laboratories. The great advantage is nothing contacts the fluid except the tubing eliminating oxidation or contamination. The disadvantage is the squeezing action damages blood platelets or similar entrained cells or sacs. Stepper motor drive would probably need a gearbox as the forces to rotate the pump are unexpectedly high.

HTH
Brian

[skimask]

It's called a peristaltic pump and is widely used in laboratories.

Learn something new everyday...
I was trying to think of how the 'gas pump' thing with the 2 opposing pistons could be done, but the peristaltic pump seems like the easiest thing to do in this situation.