Why Does a Pressure Regulator's Consistency Vary Inversely w/ it's Setpoint? 1

[WhiskeyHammer]

In my research, most manufacturers seem to list a pressure regulator's accuracy in terms of a percentage of the target output pressure. So a pressure regulator with a 1% accuracy set to 100psi will only be +or- 1psi whereas the same regulator set to say 500psi (for illustrative purposes) will be +or- 5psi.

Ive studied up on the factors that contribute to regulator stability or instability (spring rate, sensing face area, cycling of the valve stem, etc.) but I cant figure out for the life me why the consistency would vary inversely with the output pressure.

 

[Compositepro]

The consistency (or accuracy) does not vary inversely with output pressure. It is 1% of full scale. Period. This is how accuracy is defined for almost all instruments and equipment due to the physics of how they work.
Your mistake is in thinking the 100 psi and 500 psi regulators are the same. Accuracy is defined as a percentage of full scale not percentage of actual pressure.

 

[LittleInch]

As composite pro notes, be very careful that you use the right range regulator. Your post said "the same regulator". If it was the same regulator, then it's accuracy would be the same, i.e. +/– 5psi assuming you have a 500 psig regulator, regardless of the actual set pressure.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way