Using a small motor I need to be able to pump fake blood so it spurts as if being pumped by a heart for a casualty simulation charity, so it cannot be very costly. The end of a small tube is embedded in a fake wound and a motor and circuit will be between that and a bag of fake blood. This means there is likely to be a fairly constant variable slow trickle of blood at the wound with spurts this could do with being controllable so we could simulate differing heart rates and the way it initially speeds up and then slows down with blood loss, so the frequency would probably be 3hz down to 0.5hz as the frequency decreases then the pulse width of the pump being on could do with decreasing, but that may be too complex. What do you think would be the cheapest way of doing this?

Motor rating: the preferred motor is a gear pump as I already have one see https://www.ebay.co.uk/itm/DC-Micro-Gear-Self-Priming-Water-Pump-Mini-Oil-Pump-Suction-With-1M-Pipe-MO/202685568455?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
Rated voltage: DC 5V
Suitable voltage: DC 3.7-6V
Working current: 0.6-1A

 

I’d investigate using a cam which could compress the tubing and force the fluid out in spurts. When the cam isn’t engaging the tubing, the fluid would leak out under its own pressure. Or you could stop the cam on the tube to prevent the fluid from coming out. For example, before the effect is actuated.

As far as a motor, I’d consider a stepper motor. That way, you could control the cam position with a reliable degree of accuracy.

To create the effect of decreasing spurts, I’d use a microcontroller. The timing could be controlled programmatically, creating the exact effect you desire.

 

What I believe you want and what was suggested above is commonly called a peristaltic pump. I am sure a Google of the term will get you some images so you will have a picture of the general idea. You find one along those lines with a DC motor allowing you to use PWM to control the pump speed or subsequent squirt rate.

Ron

 

Your pump sounds adequate. Speed control by PWM, input to modulator a variable voltage derived from stored digital numbers, wavy line on a strip chart, or best control from a micro controller. My first attempt would be PWM motor driver controlled with a pot. to get a feel of the control.
I take it that you are not in USA?