Best peristalic metering pumps according to redditors

Like the adafruit ones? Or like these? http://www.amazon.com/Adafruit-Industries-1150-Peristaltic-Liquid/dp/B00HIX2PEG/ref=sr_1_1?ie=UTF8&qid=1419123489&sr=8-1&keywords=peristaltic+prime

If you pressurize a bottle it will drive the fluid out of it as long as the inlet for the fluid is below the fluid line. One danger is pressurizing the bottle may break it sending glass flying. Another problem is most compressors put a little bit of oil in the air it compresses. (not exactly a food grade idea.)

I have used a similar vacuum device. The exhaust is going to be a mixture of air and fluid if you attach the suction side to a bottle of liquid. It may work but you may not like the compressed air coming out of your nozzle. Again not a food grade solution.

I suggest one of these

Sound cool.

A few observations, if you don't mind me butting in.... Sounds like a really good application for a small peristaltic pump. If you are using some other type of pump, like an impeller pump, it might be higher flow than you need. A peristaltic pump and a relay would probably work.

here's one for low flow apps that is $23. There are tons on amazon and ebay:

http://www.amazon.com/ZJchao-Peristaltic-Liquid-Pump-Electronics/dp/B00HIX2PEG/ref=sr_1_1?ie=UTF8&qid=1452885463&sr=8-1&keywords=Peristaltic+Pump


I can appreciate your reluctance to use discrete semiconductors. (You are already using integrated semiconductors, of course.) It's a little trickier to make your own DC drivers out of discrete parts, but fortunately, there are many alternatives to that.

For one, you can use what's called an "H-bridge", which does both the direction changing and the driving of a DC load, and it's probably as easy to use as an SSR. You need one lead to "steer" and one lead to "drive". Another advantage of this is that you can use pulse width modulation, which preserves torque at low speeds and allows control over the speed of the pump. It also allows almost instant braking of the motor. When you turn that sucker off, it stops.

https://en.wikipedia.org/wiki/H_bridge

here is a data sheet for one from Mouser Electronics:

http://www.mouser.com/ds/2/405/lmd18200-440916.pdf


They are $15 in quantity 1.

http://www.mouser.com/ProductDetail/Texas-Instruments/LMD18200T-NOPB/?qs=sGAEpiMZZMvu8NZDyZ4K0cK2%252bZITVZKj

No harder to use than an SSR, I think. (I chose this one instead of 100 other because of its packaging. It's a TO-220 package and you can cram it into a PCB board without having to deal with surface mounting. (Heat sink it, though.)

For what you want to do using relays and slower pumps is the simplest, and using h-bridge and any pump is the most flexible.

If you want to do other things downstream of this, getting familiar with H-bridges is a good learning experience and will pay off more.

[edit: package]

this will probably prove helpful, it's a paristaltic pump so the fluidic path never directly contacts the mechanical elements (as opposed to a syringe pump). PWM-able for timing control, and you can likely control the flow rate further by using varying inner and outer diameters of tubing.

Cool! The converter I linked will need soldering, but here's one that doesn't. You should be aware that the motors you have linked offer very unreliable flow control, so use a stepper motor driven pump if you need fine control over the amount of liquid flow.