Bike pump suggestion needed for kids to pump 100 psi - Erco?
ElectricAye
Posts: 4,561
I'm mentoring a robotics team that uses pneumatic components. They have a small air reservoir (a few cubic inches) that can be pumped to 100 psi, but they have trouble using standard bike pumps to get that high, so I'm looking for something that kids can use - purely manual would be okay if kids can actually use it but I'm guessing such a pump would need to be battery powered and/or AC powered. Sought pump would best have a pressure gauge, too. Any suggestions? Erco? Erco, Oh Great Rider of Bikes and Seer of Bargains?
Comments
-Phil
They don't make em like they used to.
Anything over about 50PSI can actually pop out an eyeball if pointed at the face. So I has doubts about the safety of 100PSI in any context with kids. Supervision and absolutely no horseplay with pressurized air are important.
-Phil
The kids are about 11-13. I've had them try "floor" pumps but they can't handle it. The kids weigh something like 80 lbs. I think.
It's an interesting idea. I'll need to check if CO2 is allowed. It's not clear to me how that little gadget regulates or indicates pressure, however.
Yes, this is what I had in mind. And I was looking for a specific brand, if possible, preferably based on recent experience.
I agree. Considering how paranoid schools are about everything, I'm somewhat surprised they let this one slide. But I try to teach the kids how to survive in the real world rather than keep them in the liability bubble, so if the school lets them use 100 psi, I'll teach them that.
Luckily the reservoir tank is only about 1.5 inches by 4 inches, and the actuator pistons are only about 0.4 inches in diameter, so the forces aren't too bad so long as something doesn't snap loose and fly into their faces. I'm not sure how it compares to rubber band forces, which they are allowed to use, too. Safety glasses are required but I guess I'm still liable for their teeth. (Here you go, kiddies, polycarbonate mouth guards courtesy of PhiPi's laser cutter...)
Anybody have anything good to say about those pumps you step on? or maybe the type you connect to a drill? I bet a large tank of compressed air wouldn't be allowed in the school buildings - there's probably some rule about the tank size, I'm guessing.
-Phil
I was thinking of something that looked like this:
What about using something like this as a refill station: http://www.menards.com/main/tools-hardware/power-tools/compressors-and-pneumatic-tools/compressors/tool-shop-5-gallon-air-tank/p-1442772-c-12910.htm
-Phil
That would work great! I need to find out if such a tank would be allowed in the schools, though. I vaguely recall there might be some kind of tank size limit, or some sort of equivalent kiloJoule storage limit or something weird like that. Heck, if such a tank is allowed, maybe the kids can run it as a fundraiser at events - fill your robot tank for half a buck, etc. Anything would beat watching 80 lb. kids trying to wriggle their entire weight onto a bike pump... or their antique mentor slipping a disk on the thing.
There is PVC pipe that can handle much higher pressure than 100 PSI, such as schedule 40 and schedule 80: http://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-d_796.html
stainless steel tubing and fittings?
I've never seen pvc that could safely handle that kind of pressure. I say that out of ignorance though and I'm not surprised that new pvc can take that kind of pressure. With past experience in dealing with hydraulics and other "high pressure" systems it's important that ALL materials be rated for the pressures involved. There's a lot of energy involved at those pressures and safety has to come first.
It's common for these teams to use flexible Polyurethane Tubing (5/32" OD) for their connections. I've also known some teams that cheat (or, in their own words, allow for leakage) by pressurizing these systems up to 150 psi without any problems. I've not heard of any issues with these components at that pressure. I think the biggest danger is when they use a combo of pneumatic cylinder and rubber bands, a configuration in which the actuators pull back a rubber-banded catapult, for example, then quickly release it.
If all the tubing and fittings were SS and the pressure was only 130 PSI, either inappropriate fittings were utilized, a faulty fitting or tubing was installed, or someone caused a rupture.
Consider the lines used on pressure washers, which are normally rubber or plastic. Pressure washers are commonly rated at 2000 PSI or above.
I remember an episode of "This Old House", from probably 20 years ago where they went to a factory that made PVC pipe. They showed the QC department testing a piece of pipe that was about 4-6" diameter with many hundreds of pounds of pressure. It swelled to about 3 times maybe 25% more than the original diameter before it finally popped. I was pretty impressed.
edit: Okay I probably didn't remember perfectly, but just search PVC burst test on YouTube. PVC pipe is pretty tough.
To extend this comment. Floor pumps or portable air pumps that are advertized as suitable for road bikes use smaller pistons and pump to 100psi fairly easily. If you do end up getting a portable pump, make sure it has a short hose between the pump and fill fitting. This keeps the fill fitting from leaking while you pump.
Personally I have a "JoeBlow Sport" floor pump from REI that's easy for me to pump to 85psi. I've also used a $10 12V electric pump that boasted up to 250psi. (I expect that's the pressure that stalls the motor) Both work well.
Marty
... or hit the hobby store for a compressor used with airbrushes.
And I wouldn't suggest PVC or ABS pipe as a storage tank WITHOUT using threaded fittings. But, 'black pipe', the type used for natural gas pipe in the house, it a better / safer option, or even 'RIGID' / IMC type electrical conduit could be used, again with threaded fittings.
After pondering this, I think I'll try this or something very much like it.
Thanks to everyone for your insights and pressure concerns. Much appreciated.
I told him that I would take care of disposing it.
Turns out it is rated for 100 PSI. I took the coupling off and took a long drill and pierced the bladder.
Now it fills my tractor and trailer tires after charging it off my compressor.
My friend's son has a scar right near his eye where he was hit by a piece of PVC shrapnel, he was testing a pneumatic launcher for the Scan Eagle UAVs. PVC pipe is pretty tough, right up until it isn't.