I don’t know much about pneumatic engineering, so I need a little advice/confirmation.
I asked earlier about a different setup, but I think I’m going to go a different route.
It’s my understanding that most mini 2-way air solenoid valves will operate properly even down to 0 psi. Is this true? I need it to operate properly at around 1 or 2 psi. The valves will all be normally closed and each will only open while its own button is actively depressed.
Second question: The mini solenoid valves I am looking at are 9 volt. Can I operate this directly with a nine volt battery with no other device needed to mediate? Also, since each push button for the solenoid valves is only consuming electricity while depressed, and only one will ever be pushed at a time, can I use just one nine volt and wire it to all three buttons? Or do I need to have 3 separate batteries for each button?
You can use a single battery. Depending on the solenoids and how they operate you may not be able to have more than one open at once. I assume these are configured to be closed when there’s no power. You can use a 3 way switch to control them making it simple.
Could you explain what you mean, and how that would effect operation? Is is something I could resolve quickly with a few tests of different gauge wires, or is it something that might surprise me one day in operation?
And to answer Tripolar, they are designed to be always closed except when a button is pushed, and only one will ever be open at any one time.
It sounds like a small solenoid you will be using so if your circuit is very long for instance like 5ft or 6 ft and you notice it isn’t working right try going up a size. I don’t have a recommendation for size because I don’t know what you are working with. I worked with solenoids in industry quite a bit and would sometimes have to upgrade my wire size especially on longer wire runs. Just something you might need to be aware of of it isn’t working.
Some “solenoid valves” are pilot operated valves that depend on higher pressure to open the full flow valve. The solenoid is low power because it moves a tiny valve to provide upstream pressure that opens the main valve.
Solenoid valves like these are higher power and use the solenoid to open the main flow passage. McMaster-Carr is a good source of stuff you never knew existed BTW.
I like these pinch valves. Normally closed, small, and low power. Some similar options in Mcmaster Carr.
One thing you haven’t addressed in either this, or your other thread is the volume of air you are wanting to control.
In your diagram, you have a component called “Flow Control”, which I would assume is a regulator. Now simple regulators are just a small orifice where you get a pressure drop depending on the volume passing through. At no flow, there is no pressure drop, so the full pressure of the mini CO2 cartridge (~400-800 PSI) in all your lines. When you opened one of your solenoid valves, you would get a brief high-pressure blast, which would quickly drop to a set pressure, depending on the volume of CO2 passing through the system.
You could get a diaphragm regulator, which is more expensive but limits the downstream pressure for a large range of flow rates. So, if you set the pressure at 2 PSI, that is all you would get when you opened your solenoid valve. Again, this solution has a higher cost.
Have you considered replacing both the mini CO2 tank and the “Flow Control”, with a fan? Again, the size of the fan, and how much noise it would make, would depend on the volume of air you need.
How do you propose to get from the 850 psi cartridge pressure down to 2 psi? I think this will take a 2 stage regulator, quite a large device compared to the size of your other components.
OK, I did find a mini 2 stage designed just for CO2, but it only goes down to 7 psi, nothing about its flow rate.
Thank you! This is the type of information I need. I had no idea that the initial release would be at full pressure before dropping. I’m not sure if that would damage the device I’m passing air through or not, but its very likely. I will look into the diaphragm regulators you talked about and also the aquarium pump idea. As to the volume of air: I don’t have a precise figure. I’m thinking around 1 liter released in about 4 to 5 seconds.
mixdenny: I will look into that regulator you linked to. Used with the rest of the design, an initial burst at 7 psi which dropped immediately to 2 psi probably wouldn’t hurt.
Nefario: Thanks for the link, I’d prefer to order from a trusted source. I’ll see if they have something that suits my purposes.
HoneyBadgerDC: Thanks for all the input. The size is fairly small. Two of the wire runs will be about 12 inches, and the third will be about 4.5 feet. I will probably up the wire size on that one based on your input.
I found an ultra-miniature two-stage diaphragm regulator that says it can control down to 0 psig, and says it is ideal for the low ranges I’m talking about. Perfect size too. “About the size of 10 stacked quarters”! LINK to regulator.
The only problem is that it has a max inlet pressure of 500 psig, and the CO2 supply is at 850-ish. What should I place between the CO2 supply and the mini-regulator to step down the pressure without damaging anything with pressure drops and increases when changing CO2 bottles?
