Diameter Gauge


Our diameter gauge measures pulley diameter with unparalleled precision and provides a means to accurately predict fan airflow between pulleys in seconds.

SKU: 667438785659 Category:


FPP -1 (Fixed Pitch Pulley Apparatus)

This model, FPP-1 is made specifically to measure the diameter of a pulley. It comes with a handy performance chart that is used to accurately navigate the airflow of a fan from one pulley to another in seconds. The diameter gauge is compact and unlike other measuring devices, it does not straddle a pulley to measure the diameter.

Changing Airflow is a Breeze – Example

Design Airflow = 4000 CFM

Present Airflow = 5000 CFM

Action (reduce) = 1000 CFM (reduce to 80% of 5000 CFM)

Pulley size = 6” (Diameter)


From intersection 6” pulley, on the chart, scroll to the left along the 6” row until you get to desired target.  The closest you can get to 80% is 79% by using 4.75” pulley. (See Chart Above).

• No calculation or tachometer required.

• It saves time, a lot of time

Technical information

• Measures up to 11.5” diameter

• The indices show the diameter of the pulleys most used in air movement.

• Packaged in a crash proof box.

Additional information

Weight 8 lbs
Dimensions 9 × 8 × 1.5 in