[unclebilly]

Gauge accuracy is usually 2-3% of full scale. A 100psi gauge would have 2-3 psi of error.

This was fun for me in my previous life. I invented a oilfield completion system that opened based on pressure down hole. Here are the variables... the accuracy of the gauge on the pressure truck they use to open these, the density of the fluid in the wellbore (is it fresh water, brine, KCl water, etc).

Regardless, this system has 30% market share in North America and even higher in Russia and other parts of the world...