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Welcome to the STIHL USA Blog

Monday, January 18, 2016

Clearing the Air on Blowers

Science provides a new way to measure blower performance.

When you use a STIHL blower, the performance is easy to see. On paper, however, things become less clear. Different manufacturers use different testing standards and practices to achieve their results. This makes comparison shopping confusing and potentially misleading. That’s why STIHL is adopting a new, simple way to compare blower performance: Blowing Force.

The Problem

Traditionally, blower performance is measured two ways: air velocity and air volume. How these metrics are tested, however, varies greatly, which impacts the results. For example, if a handheld blower with a 25 cc engine is tested with its tube removed, then on paper it could produce an air volume nearly as high as the professional-grade STIHL BR 430 – which has a 63.3 cc engine! Since testing conditions can be manipulated, manufacturers have an opportunity to inflate their blower specs, appearing more competitive than they really are.

The Solution

A measurement method has been introduced by the American National Standard Institute: ANSI B175.2. This new method lays the groundwork for how blower specs are to be determined – and the way it does it is completely different than what you would imagine. ANSI B175.2 measures the force generated by the actual airstream produced by the blower, dramatically increasing testing accuracy and consistency.
Whether it’s a handheld or backpack blower, the tube is placed about five inches away from a 14-inch disk connected to a force sensor. The resulting force is measured in Newtons [N] – a unit of force. Simply put, the higher the blowing force, the greater the clearing power.

The Science

A Newton is a unit of force, combining air velocity and air volume into one easy-to-understand unit of measure. Consumers may find it surprising that the other more traditional blower specifications such as air velocity [mph] and air volume [cfm] are calculated values. To determine these values, the blowing force is combined in a system of equations with other factors such as tube diameter, air pressure, temperature, and humidity. The resulting values are average air velocity, max air velocity, and volume. Average air velocity best represents the air velocity across the entire air stream. Max air velocity is the velocity at the center of the airstream, which receives less interference from other sources.
You can see the performance of STIHL blowers under this testing method in this chart.