# Psi -> pounds lifted?

1. May 21, 2010

### thumperj

psi --> pounds lifted?

I have a very, very small air compressor that puts out 0.8 bar or 11.6 PSI. I would like to know how to compute if I were to put a plastic skin over the top of the output (like a balloon), how much weight could be lifted by the air compressor.

I realize that part of the equation is going to be the stretchiness of the skin. Here’s the skin I'm using right now: https://www.amazon.com/gp/product/B000RFU0PS/ref=oss_product (Of course, I’d prefer to understand how the skin factors into the equation so that I can learn and do this myself.)

For a simple visual, think laying a book on top of an inflating balloon. How much can the book weight before the compressor maxs out?

Thank you in advance for some guidance.

2. May 21, 2010

### lilphil1989

Re: psi --> pounds lifted?

Pressure is a force per unit area. Assuming the force is uniform across the nozzle, then the total upward force should be P x N, where N is the nozzle cross-sectional area.

In order to lift something, this force must overcome gravity, ie PN > mg, where m is the mass of the object to be lifted and g the acceleration of gravity.

The condition PN/g > m places an upper limit on the mass you can lift.