What is parallax error and how can I avoid it?

What is parallax error?

Parallax error is when the pointer of a device looks like it’s at a different reading when read to the side compared to when read face-on.  This is caused by the distance between the scale and the pointer. Because they’re not on the same plane, readings may not appear accurate when viewed at an angle.

When might I see parallax error in my readings?

Dial-type instruments like pressure gages or thermometers might be affected by parallax error if they are being monitored to the left or right of the device.

What can be done to fix it?

High Accuracy Magnehelic® Differential Pressure Gage, Series 2000-HA

The easiest solution to avoiding parallax error is to read the device directly from the front of the unit. The high accuracy Magnehelic® gage offers a mirrored overlay as standard in order to eliminate any parallax error when taking measurements. When you’re taking measurements, you’ll want to make sure to view the scale at the place where the pointer and its reflection overlap; this will ensure your readings are as accurate as possible.

If you have any questions about selecting products for your application, the Dwyer Applications Engineers are available to assist by phone at (219) 879-8868 x6402, or by email at tech@dwyermail.com.