The NFPA needed to address the inconsistencies in force specifications published by the various rescue tool manufactures. Some manufactures will publish forces measured or calculated at points on the spreader that are, for all practical purposes, are unusable.  Spreading forces published as “per arm” are blatantly misleading.   Although this manufacturer does not instruct you to multiply the published “force per arm” times two, this is what the end user usually assumes. This is not correct and is one of the reasons the NFPA developed a spreading and pulling performance test.  This test was devised in order to bring uniformity to spreading  tool specifications. These tests provide your department with legitimate  means of comparing compliant tools. The forces are measured for spreading as HSF (highest spreading force) and LSF (lowest spreading force). For pulling they are measured as HPF (highest pulling force) and LPF (lowest pulling force). No longer do you have to compare spreading forces that are achieved in unusable places during the spread, or on the spreader arm. This also uncovers the blatant misrepresentation of spreading forces listed “per arm”. In this test the tool’s spreading force is measured 1 inch in from the end of the tip at 10 uniformly spaced points, ranging from the closed position to 95% of the maximum opening.  The value of the highest point is referred to as the highest spreading force (HSF) and the lowest point as the lowest spreading force (LSF). A similar test is performed to determine the pulling force. This is done by measuring the pulling force at 10 uniformly spaced points, ranging from the full open to 95% of the closed position. The value for the highest point is referred to as the highest pulling force (HPF) and the lowest point as the lowest pulling force (LPF). This gives a very precise way to measure these forces and a meaningful way of comparing them.  The key in determining a powerful spreader is in its primary use:  spreading a door off a car.  When the evolution is performed, the spreader is almost always closed as the purchase point is typically very narrow i.e. seam between the door and panel.   The NFPA force you are using in this situation is the LSF or Lowest spreading force.  In EVERY spreader manufactured,  the weakest force is always when the arms are closed because of the basic laws of leverage.  As the spreader arms open, they gain spreading force because the arms are gaining leverage against whatever they are pushing, but what you need is MORE POWER UP FRONT to gain that initial purchase point.   Therefore, you can determine the strongest spreader, by determining the highest LSF amongst manufacturers.  To see a Genesis published NFPA sheet on spreaders and LSF click here.