Question about Air Pressure Regulation Under the Spherical Wheel

[IrisvandenHeuvel]

First of all, thank you so much for sharing all this information—it's very helpful. I had a question regarding the regulation of air pressure underneath the spherical wheel. Specifically:

• What is the source of the air pressure?

• How much bar is required to make the wheel (including the animal) float?

I tried to trace this information in the documentation but couldn’t find it. Any clarification would be greatly appreciated!

[noahpettit]

Hello,

I don't have themost up to date knowledge as I have left the harvey lab but here is the info I do have:

1. We use house compressed air passed through a filter and pressure regulator.

2. I think pressure was set to be around 20-40 psi, adjusted such that the ball is spinning freely with little friction but isnt shaking / vibrating.

Here is some additional information from my notes / previous correspondences about the air supply. More than you asked for, but it might be useful to someone in the future:

For the air supply, we use house compressed air. This is connected to a pressure regulator to allow for flow control which is then connected to 1/4" pneumatic tubing that is the type compatible with press-in connector / fittings. I don't currently have a part number for it but i think it's the same stuff as this: Utah Pneumatic 1/4 Dot Air Line 0.25" Od 32.8 Feet 10 Meters Saej844 Nylon 1/4 Hose Dot Approved For Air Tubing Air Brake System Or Fluid Transfer 1/4" Air Hose (1/4 Air Line)

That tubing is then fed into the rubber stopper, which connects into larger diameter duct hose + duct hose fittings that then connect to the ball cup base (see lines 20, 21, 23 of parts list spreadsheet). Note that where the 1/4 tube meets the duct hose there will be a lot of turbulence and thus loud audible noise, so it can be useful to have longer stretches of duct hose in order to create more laminar flow and make it quieter. For auditory experiments, several meters of duct hose nearly coiled will drastically reduce audible noise although there will always be some from the ball cup. I imagine one could also experiment with 3d printing or buying some kind of laminar flow nozzles / interfaces for a more compact solution if noise is an issue, i have not tried though. You may need some duct tape or zip ties to secure some of the connections.

Old pressure regulator:
Norgren, Series R73

Old filter (no longer available, I think):
Dr. Guilbeault, DRG20V, DRG20VE

New combo pressure regulator and air filter:
Speedaire, 4ZK76A

You probably want the new combo pressure regulator and filter, although I think the old filter was much better, so if smells from your air source are a concern (for behavior robustness or experimental reasons) you may look into getting something equivalent in addition to the regulator (there seem to be quite a few options when i did a quick search). In the last image you can see the types of fittings we use for the compressed air lines - something like that is essential for getting compressed air to and from the regulator/filter but ultimately the line should be expanded into the larger duct hose before it reaches the ball cup.

not sure about flow rate but psi is around 20-40