Inches of Water Pressure Unit

You must know the temperature reference used by your company and for the application to accurately calibrate pressure instruments. Pressure Unit conversion charts do not always specify what temperature the conversion factor is referenced to, causing confusion.

There are three commonly used reference temperatures for inches of water column. They are 4° C (39° F), 60° F, and 20° C (68° F).

The difference between inches of water pressure units can cause about +/-0.1% to almost 0.2% error. For a 1% calibration, this might not matter but for higher accuracy, it’s significant.

You also need to know the reference temperature used by your inches of water pressure calibration standard. 20° C (68° F) is popular but some manufacturer’s use 4° C (39° F). Some calibrators have selectable units for inches of water.

See The Truth About Height Based Pressure Units by Mike Bair of Fluke for more information and Unit of Measure Converter for a good Windows utility from Fluke.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.