Hi,
What is the best way to pour small amounts of liquid (~5-50ml)?
I'm going to use scale to measure how much liquid was already poured into the container, but I'm not still sure how to pour it.
Let's assume I could place the tank above the container that is going to be filled, so I don't have to use a pump. I was thinking about using some electric valves but I'm not sure if they are going to be fast enough to close - I'm worried that they are going to have a big flow. And they are expensive.
So another option I was thinking about was using some small electric water pumps. This one says it can pump 120liter per hour, but in the description is written 80-120 liters per hours, so I think that at the lowest voltage it could pump 80 lph. But that means ~1300 ml per minute, which is ~22ml per second, so it's going to be hard to pour with 5ml precision.
Anybody has idea how to make it accurate and cheap?
Thanks.
Syringe (readily available in 1~60ml sizes). Screw threaded into a nut mounted behind the plunger, connected to motor. Stepper motor sufficiently beefy to overcome the friction of the screw threads in addition to applying the necessary force to move the plunger, or maybe a gear-reduction motor with sensor to count revolutions (to address problem with getting enough torque out of a stepper motor).
Some mechanical challenges here, but that would be my general approach.
If you are using a gravity feed and if you flow through a soft plastic or rubber tube you could use a servo to squeeze the tube shut to cut off the flow.
Robin2:
If you are using a gravity feed and if you flow through a soft plastic or rubber tube you could use a servo to squeeze the tube shut to cut off the flow.
...R
I'm afraid that the tube will break soon and I will also have to use powerfull servo to squeeze the tube to stop all the flow, even the dripping.
DrAzzy:
Syringe (readily available in 1~60ml sizes). Screw threaded into a nut mounted behind the plunger, connected to motor.
Some mechanical challenges here, but that would be my general approach.
I need to have a big tank as a source, so another challenge will be how to automatically fill the siringe (maybe servo-controlled arm to move there and back?).
groundfungus:
A peristaltic pump can pump very accurate amounts of liquid. They are often used for dosing aquariums. Ebay has a selection of inexpensive pumps.
Looks great, but they seems a bit more expensive (6USD isn't much, but there will be many of them)
terryking228:
Hi,
Look at 12V Windshield Washer pumps. available at your local car parts place, or the junkyard.
I think they can be run pretty slow if desired. Or restrict the flow to get more accuracy.
Thanks! I have few of them lying arround and I if they pump too fast, the could run slowly at smaller voltage, squezing the tube a bit could also slow it down. They could also be found at AliExpress for as little as 3USD, making it a very cheap solution.
parmanik:
I'm afraid that the tube will break soon and I will also have to use powerfull servo to squeeze the tube to stop all the flow, even the dripping.
That depends on the material the tube is made from. Peristaltic pumps work by squeezing tubes.