Inflate a small balloon with 2 scenarios

Hi there!
I would like to build a small "PLC Hacking Demo" using an Arduino, an air pump and a balloon.
This is the scenario: I have a workstation where I can control the PLC (aka Arduino) to inflate a balloon until it reaches a normal size. The arduino and the pump/compressor should be programmable so I can enter a PSI value for the normal size and the pump stops. It should also be able to show me current value (electronically on a display). The "bad hacker" then hacks the workstation, changes the psi value while the display shows a false value. The balloon explodes

So this is basically a very, very boring version of "Stuxnet"

I need your guidance on the parts you would recommend for this project. I'm having particular difficulties to find a suitable pump that is small enough to be transported from demo site to demo site. I looked at several 12v compressors but they are to large, heavy and can't show/set the air pressure precise enough.

Is [u]this[/u] too big?

Or, maybe just a pre-pressurized air tank that can blow-up several balloons before being re-charged.

and can't show/set the air pressure precise enough.

I'm not sure how you measure such low air pressure. I don't think you'll find a compressor/inflator with a low-pressure sensor built-in. But, maybe you can adapt something that measures atmospheric pressure? ...If you drive up a mountain there's not enough pressure change to inflate a balloon, but a barometer can measure the change.

Do you have any idea how much pressure is in a balloon? I don't....

To inflate a party balloon you don't need more than 2psi. So you need a low pressure high volume compressor.

Instead of pressure sensor I would use a magnetic reed switch that gets triggered when balloon inflates enough to touch it. Saves money for multiple switches with valves, to inflate more balloons at the same time.