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Food safe pump

Hi everyone!

I'm working on a halloween costume where I want to have a container of liquid on my back, a hose from said container running down my left arm and a way todispense the liquid through the hose. Right now the dispensing is the problem.

Would a windshield washer pump be reasonably safe to use for something that is going to be consumed? I'd buy a new unused one of course.
If that's not a good idea, what would be?
I've experimented with a can of compressed air to push the drink out but was not fully satisfied with the result.

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Jayefuu3 years ago
What about a modified water pistol with the hose from the tank to the nozzle extended? Or is that too high a flow rate?
Kiteman Jayefuu3 years ago
Just what I was thinking - you can buy back-pack waterpistols, which should be ideal.

Alternatively, you can get back-pack garden sprays, which have a long, thin delivery tube for getting in and around bushes etc.

In both cases, buying a new model, and then running fresh water through it, should be fine for spraying food-quality liquids. Afterwards, before storage, empty them, rinse with clean water, then run a sanitising liquid through them, such as the solutions used to clean baby bottles.
Jur (author)  Kiteman3 years ago
So, I've decided to go for the pump solution (found a cheap pump that should be safe to use) and now I have a quick question about the circuit I'm planning to use to power it; will an L.E.D. need a resistor if it's hooked up in series with a relay (for controlling the pump), or will the coil resistance be enough?
What viscosity are you trying to pump ? Something watery ?

You NEED a resistor. The relay is very low resistance, and unless the relay draws only 20mA when its on, it won't have enough resistance to limit the LED, so the LED must be in parallel with the coil instead.
Jur (author)  steveastrouk3 years ago
Yes, it will be a drink being pumped.

Ok, I think I understand but I might as well make sure;

If I use this relay (https://www.elfa.se/elfa3~eu_en/elfa/init.do?item=37-210-32) I can put it in series with an L.E.D.+47ohm resistor and power it with 3.3VDC to control a pump running on 12V?

I want the LED to light up when the pump is turned on.
LikeI said don't put the led in series with the relay, put it in parallel with it.