Liquid flow control

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I realize there are solenoids that suit my purpose better. But the ones I've got I've already got.
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Have you tryed your solenoids both ways? It will open one way a lot easier than the other. Andy
 

Yeah, I'm going to get some 2-hole rubber stoppers and an aquarium pump soon, and give that a go. My big concern with that plan is the hole size in the stoppers seems to be 5mm, which may not be big enough for decent liquid flow.
 
A kluge...one hole stopper with an adequate size hole for the outlet tube, and a hypodermic needle through the stopper for the pressurizing air supply.

Ken
 
My big concern with that plan is the hole size in the stoppers seems to be 5mm, which may not be big enough for decent liquid flow.
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Its rubber make one hole bigger.
 
I just did a quick n' dirty test with an aquarium filter, a coke bottle, my solenoid, and a pile of plumber's putty. It leaked a lot, but the pressurized flow activated the solenoid (albeit fairly slowly)! Note that I used the 5mm tubing for both the air intake and the water to the solenoid.

Now, since the solenoid activates at 2.9 psi, and that's EXACTLY the rating of the pump I picked up, am I going to need a bigger pump to handle 6 bottles? Note that only one of them is going to be active at a time.
 
Drilling or redrilling rubber stoppers is a real pain, especially if they are the small ones like sgpope would need for liquor bottles.
Click to expand...

Use a round file in a drill to open the holes up.
 
Now, since the solenoid activates at 2.9 psi, and that's EXACTLY the rating of the pump I picked up, am I going to need a bigger pump to handle 6 bottles? Note that only one of them is going to be active at a time.
Click to expand...
That will depend on the CFM of the pump and the flow out you want. Sounds like a small pump and it may not move enough air to get good flow.
I would use a higher PSI anyway so the opening and closing of the valve is more consistant. If you need more CFM you could hook two of them up to all 6 bottles. So fix your leaks and see if the flow rate is enough for you. It should not change when you hook up all six bottles. Andy
 

I swapped out the one I had for a slightly bigger one. The new one is rated at 4.35 psi, and has a flow of 200 l/h (0.12 cubic feet per min). I'll give it a try when my rubber stoppers arrive in a few days.
 
Ok, my rubber stoppers (finally!) arrived. I tried a test last night with a single bottle. It looks like the flow of water decreases significantly as it's being poured.

My test:
- set up circuit to activate solenoid by a push button
- attach 2l coke bottle (half full of water) upside-down to apparatus, with aquarium pump and solenoid connected through the stopper
- measuring cup beneath solenoid
- turn on air pump, wait for bubbles to stop entering the coke bottle
- hold down push button, start timer
- dispense 2 cups, recording time of 1 cup and 2 cups

1 cup took 13 seconds, and the second cup took another 19 seconds. Looks like the air pressure is dropping significantly.

Should I get a different pump? What about a second pump? Am I perhaps doing something wrong?
 
You need to maintain a constant pressure. Perhaps a different pump, or better, a relatively large pressure reservoir tank.

Ken
 
By different pump do you mean possibly a larger aquarium pump (which will basically double the pressure), or something else entirely?

Sorry for my ignorance, but I've no idea what a pressure reservoir tank is.
 
Yeah, a bigger pump. But, that won't keep a constant pressure. I would go with a bigger pump, a pressure tank several times the volume of the your liquid containers, and a pressure switch to control the pump.

ken
 
Yeep! Just checking out pressure tank prices. Seems like this is getting a little out of control. Hmm..constant pressure. What about if the pump was only turned on when the liquid was flowing? Wouldn't that make the pressure constant?

Maybe I should take a step back and consider another method of determining the amount of liquid in the cup.
 
No, the system will usually have some leakage. So the system starts with low pressure and builds up as long as it runs, or until it reaches it's maximum pressure capability. If there is no leakage, the pump has to try and start with a full head pressure...and may not like that.

Any container that will hold the pressure can be a reservoir. Well...any clinically clean container.

Ken
 
I just did some tests with turning on the pump and solenoid at the same time. It took about 2 or so seconds to get up to full capacity (probably the leakage Ken was talking about), then it was working fine. Consistent (but kinda slow) flow from that point onward.
 
At this point you have work with the trade off of using the valves you had. If you what soming better then get the zero pressher valves. A larger pump may help, but if you are getting new stuff consiter the right valves that would not need a pump.
 
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