I am building a motorized pipette for aspirating and dispensing fluids. Ive been looking for an air pump that can create and hold a vacuum to draw water into a plastic tip. Also, I am looking for something that has variable speed control so I can vary the speed the liquid flows. What type of pump would be good for this? I believe it is either a diaphragm pump, vacuum pump, or some other type of positive displacement pump but couldn’t find literature to back it up. Any help is appreciated. There is some patents I attached of what I am basically modeling my design after:
along with pumps that come from manufactured motorized pipettes:
, if anyone can tell exactly what types of pumps these are based on the photos that would be a great help!
One additional thing is that I want to be able to suck air in and blow it out of the some nozzle/tubing. Are there any pumps with this ability or valve systems that could accomplish this?
Thanks!
The ones you linked are just membrane (diaphragm) pumps as far as i can see ... there are also commercial units (NOT certified for medical use) much more cheap ( example ) if you just want to try ... but i suppose the main "trick" in these commercial motorized pipettes are the airswitch valve (that connect suck or blow terminal of the pump to the end tube) and probably a pressure reducer (something that regulate the flow for vary the speed that the unit suck or blow in the aspiration pipette, i don't think it's made changing the speed of the motor ... as you can see from the patent drawing the buttons, other than act the valve, just close a switch)
I know there are small pumps that suck when the motor turns one way and blow when turned the other. I have several from scrapped circuit board repair stations. If needed, I can see if there are names and models on the devices.
Paul
Hey Etemenaki—
Thanks for the reply! That helped me to confirm the type of pump I am looking for. I am a bit confused on the second part of your explanation. Are you saying that a pressure reducer might be used to vary speed of flow as opposed to the pump being programmed like that?
The pump is a diaphragm pump powered by the 12 volt motor. There is no mfg. so the pump was assembled from pieces at the equipment factory. The green frame is plastic injection molded as is the eccentric and connecting arm.
Paul
davidjcshennn:
... Are you saying that a pressure reducer might be used to vary speed of flow as opposed to the pump being programmed like that?
Yes, and i think is the only "safe" mode for do it ... i mean, if you connect directly a pumo, also one small as the one i linked, to a pipette, it just suck all the liquid to the pump (or just spit it out quickly if in blow state) without a system that slow down the speed the air pressure (positive and negative) is applied ... in pneumatic automation this "speed regulation" is made using pressure regulators (or more exactly called flow regulators, cause they act mainly on the flow rate than on the pressure), like as example these ones or simlar units ... in that automated pipette is probably (i suppose) built in the 2-way valve (that is not specified in the draw, but mentioned as a different patent number), at least i suppose that, cause there is no reductors drawed in the project ...
Basically, at build level, they are just finely regulable "pin faucets" (sorry, don't know if there is a more correct name in English, in Italian they are called "rubinetti a spillo" ), that left pass just the flow at the speed you decide, in both directions ... trying to do the same thing varying the speed of the motor i think don't work, also using gear-pumps (more precise, but not too good with air, they are mainly for liquids), with membrane pumps also worse ...
Etemenanki:
Basically, at build level, they are just finely regulable "pin faucets" (sorry, don't know if there is a more correct name in English, in Italian they are called "rubinetti a spillo" ), that left pass just the flow at the speed you decide, in both directions ... trying to do the same thing varying the speed of the motor i think don't work, also using gear-pumps (more precise, but not too good with air, they are mainly for liquids), with membrane pumps also worse ...
