Hydraulics and Pneumatics

[cypressfalls Robert]

I think water would respond faster.

Your syringes can't leak? That's a problem for us.

I just tryed it and water actually slowed the syrringes down alot...they don't move with a 1KG weight on top , but with just air it moved perfectly
and yea they do leak a bit but only if they go on their side or someting, just keep them upright.

[Primate]

Hydraulics is technically more powerful, since water is non-compressible. With air, you'll get a little bit of play, due to the nature of gases. So in theory, you'd want to use hydraulics.

Of course, it's not that simple. Simply put, water is a mess. Unless you can invest in some decent syringes and tubing (with quality seals), it'll be leaking all over the place. Stick with pneumatics, and just design your device so the second syringe doesn't have to apply a whole lot of force. Popping a balloon is a good option, or you can have it push a switch to activate a circuit. Petco has cheap syringes and fishing tubing you can pick up for under $10.

[Paradox21]

I have 2 reasonable quality syringes and some very tight fitting aquarium tubing, and I have had them sitting in my Mission Possible for several weeks without any leaks.

[aubrey048]

I'm curious . . .
A) How can you use a syringe to help accomplish a MP task? Do you inject water out of it and propel the golf ball through a tube of PVC pipe? (Just an idea)
B) What kind of syringe is this? I used to have one of those that you inject glue into things with. Is that what you're talking about? (If so, I know you can purchase that kind online . . .)

[Dark Sabre]

A) Depends on what's pressurizing the syringe. If you have enough force, you can move objects. If you don't have much force, you can push switches. Or you can push switches even if you have a lot of force

If you have gone through the thread, you probably saw the link to my Hydraulics Wiki. That's what I did.

[Uncle Fester]

DS, as usual. speaks (writes?) great wisdom. At Mission I ran at an invitational yesterday, a hose broke loose off a car windshield washer pump after running out of distance to push a syringe. Water sprayed over thirty feet and nailed a bunch of HS students with quite a bit of water. never saw so much squealing and running. the girls were upset too.

Absolutely the best worth-the-penalty boundary violation I have ever seen in 19 years.

[Dark Sabre]

And this is why you have the switch that the syringe hits have both NO and NC circuits. You use the NO circuit to trigger the next action and the NC circuit to turn off the pump!

[aubrey048]

ONCE AGAIN, I have a question. Can someone define an enclosed hydraulics system? Is water falling out of an uncorked hole in one cup into another cup to set off a reaction enclosed? The water never LEAVES the system entirely. Thanks in advance. I really appreciate it.

[Dark Sabre]

It sounds like you may have already read the recent FAQ about hydraulics.

If I understand your setup, you are releasing water from one cup into another and presumably using the weight of that water to initiate some action.
To the extent of my understanding, they would define two syringes hooked together as "entirely enclosed" since there is no water exposed to atmospheric pressure. I don't think that pouring water from one cup to another is at all "enclosed".

Looking at, for example, hydraulic brakes:
There is a reservoir that the system draws from that is essentially open to the air. It is usually covered by a plastic cap to prevent spillage, but it isn't sealed against pressure or anything.
The fluid is drawn through the master cylinder setup and taken to high enough pressures to provide the force on your car's brakes.
To me, like the windshield-fluid pump setup that I advocate, it is a clear demonstration of hydraulics. The part of the system where force is actually being transferred (where the hydraulics is happening) is enclosed and pressurized, but there is the "open" reservoir that the system draws from. I dunno.

Either way, I don't think pouring water between two cups is enclosed.

[aubrey048]

Thanks again for answering my question, Dark Sabre!!! Now I'm going to go fix up step F.