NFPA Cut Ratings and NFPA 1936 – What You Need To Know
Did You Know?
Did you know that NFPA not only makes your tools safer, but the NFPA Standard can actually help you decide which rescue tool brand outperforms the rest? This is just one of the many facts about NFPA 1936 that a lot of fire departments overlook. This and other truths, are listed below to bring you up to speed on NFPA 1936 compliance and ratings quickly.
5 Facts You Should Know About NFPA 1936
FACT Number 1 – Safety
One of the reasons the NFPA 1936 standard for rescue tools was created was to give fire departments the ability to compare different brands of rescue tools on a tested performance basis. The tests were the same for all brands of tools, and carried out by a 3rd party testing agency. The NFPA 1936 standard for rescue tools was enacted in 1999. There were two main reasons for creating this standard. The first was safety. They wanted to ensure the safety of rescue personnel using the equipment. The main concern was for over pressurization of the tools. Most tools operate at high PSI (10,500psi), and a catastrophic failure at that pressure could possibly cause injuries. Therefore, the NFPA enacted a rule that all rescue tools under the standard must have two forms of over pressurization relief. The other reason for creating the standard was to create an environment where different brands of rescue tools could be compared on a common basis. There is a difference between “theoretical maximum force” and “usable maximum force.” The theoretical maximum force is a force that an engineer calculates because there is no possible way to test the force. For example, when the blades of a cutter move past each other they are still producing more force, but it is impossible to use that force because the blades have already closed. Hence, the term “Usable Maximum Force”. It is because of this marketing tactic that NFPA decided to level the playing ground and put the tools to scientific tests carried out by professionals. The tests require the tools to perform under situations where their performance can be measured and usable. For example, the cutter test provides different types, and sizes of steel to be cut by the tool being tested. The tool is given a grade on whether or not it cut a particular size of steel, and that grade is required by NFPA 1936 to be published by the manufacturer. This allows Fire Departments to evaluate rescue tools based actual performance by the tool. There are other factors to evaluating rescue tools such as ergonomics, that can only be done by the Firefighters using the tools, but NFPA certainly gives Fire Departments the ability to determine the performance of one rescue tool verses another.
FACT Number 2 – Testing Labs
NFPA requires that rescue tool manufacturers hire an OSHA approved Nationally Recognized Testing Laboratory (NRTL) to test the tools to the standards set by NFPA 1936. Once the 1936 standard was created, the NFPA stated that, “…an OSHA approved (29 CFR 1910.7) National Recognized Testing Laboratory (NRTL) must be used to demonstrate NFPA 1936 compliancy.” In other words, NFPA said we will make the criteria for the tests, and the rescue tool manufacturers must pay an NRTL to test their respective tools to those criteria. Most manufacturers will state that a tool must be UL listed to be NFPA compliant. This is NOT true. UL or Underwriters Laboratories is a PRIVATE company (not a government agency), that is paid to conduct tests on a 3rd party basis. They are an OSHA approved NRTL, which means they can be used to test rescue tools to the NFPA’s standards. There are seven recognized NRTL’s in the United States, and UL is one of them. Genesis Rescue tools are tested by the TUV group. TUV is one of the 7 OSHA approved NRTL’s in the United States. The company is based in Germany, but is recognized around the entire world as the largest and most respected 3rd party testing group. The main reason we used TUV is because of this very fact. Genesis tools are sold around the world, and UL is mainly recognized in the U.S. Therefore, we couldn’t use UL as it is not known as well as TUV, worldwide.
FACT Number 3 – Measured Results
NFPA requires a performance test for cutters, spreaders, combination tools, rams, pumps, and hoses. NFPA requires that rescue tool manufacturers publish the results of these performance tests so that Fire Departments can use them in the evaluation of rescue tools. The tests designed by the NFPA for the NRTL’s (UL, TUV, etc) to perform were created to allow firefighters the ability to compare different brands of rescue tools under the same scientific conditions or tests, conducted by a third party. Rescue tool manufacturer’s were getting, and still are getting out of line with the forces they are publishing for their respective tools. Most rescue tool companies publish an engineering calculated force, instead of a tested measured force like Genesis. The tests that are conducted allow the simple firefighter to compare rescue tools on a MEASURED test, which should eliminate the effect of the false advertising by rescue tool manufacturers. Unfortunately, it does not for one simple reason: Firefighters assume that NFPA compliance was done only for safety and legal reasons. The majority of firefighters don’t know that in order to be NFPA compliant you must test the tools to these specific criteria, and PUBLISH THE RESULTS. That is why rescue tool manufacturers are still publishing the calculated maximum forces, and showing up claiming over 200,000lbs of cutting force, but are not able to cut a “B” post. That’s why at Genesis we say, “SHOW US YOUR NUMBERS.” Most of the work has been done by the NFPA and the respective 3rd party testing groups (UL, TUV, etc) for the Fire Department looking to purchase rescue tools. A Fire Department should be able to narrow their choices of tools down to two or three competitors, based just on NFPA ratings. Then the Department can schedule the appropriate demonstrations to determine other factors such as ergonomics, speed of operation, etc. To view an example of published NFPA ratings click here.
FACT Number 4 – Logical Cutting Results
The NFPA requirement for cutters involves a performance test to prove the thickness of steel each cutter will cut, therefore allowing a Fire Department the ability to determine the strongest cutter by simply reading a chart. Published maximum cutting forces by rescue tool manufacturers, are erroneous. 90, 100, 200,000lbs of cutting force? Maybe on an engineers slide rule, but not in the real world. You see, NFPA got sick and tired of rescue tool manufacturers publishing crazy cutting forces. Forces that were calculated when the blades had moved past each other, which meant that the force could never be used, but technically was produced. The cutting test was devised to give a standardized way of evaluating cutters. The results allow the department to evaluate the performance of a cutter based on real cutting tests. This test requires that the cutter cuts 12 pieces of the largest material in each of the five categories. The tool is only allowed one set of cutting blades and each cut is made in a single continuous motion completely severing the piece of material. In order to pass this test a cutter must cut a minimum of 60 pieces of material of at least the minimum size in each category. This is an example of a cutting test result as you see below. If the cutter cuts . . .
“A”: a 3/4” round bar
“B”: a 1/4” x 4” flat bar
“C”: a 2” ID schedule 40 pipe
“D”: a 1” x .08” wall thickness square tubing
“E”: a 1 1/2” x 3/16” thick angle iron
the performance level of the cutter would be:
Though this test gives you a good idea of the power of the cutter, there are more things to consider: balance, ergonomics, weight, and speed of the tools. A cutter may be very powerful, but if it takes too long to build that cutting force its useless. Still, a Fire Department should be able to narrow their decision down to a couple of manufacturers by just requiring them to produce their NFPA cut sheet. Click here, to see an example of a Genesis NFPA cut sheet
FACT Number 5 – Realistic Spreader Numbers
The NFPA requirement for spreaders involves a performance test to identify the Lowest Spreading Force (LSF) throughout the arc of the spreader. This LSF is key in determining which brand of spreader actually performs the best. 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.
NFPA 1936 Explained
LFS and NFPA 1936
Lowest Spreading Force (LSF) will prove to be the most important number when evaluating and comparing spreaders. All spreaders, from all manufacturers increase in power as the arms open. LSF is produced at the beginning of the spread and remains steady until the arms are near the full open position, where the force then rises substantially to the HSF (Highest Spreading Force). Since most spreading operations requiring high spreading force are performed within the first 10 inches of opening, the LSF will be the mot important number to consider. Do not focus on a sales technique the emphasizes HSF!
Usable Spreading Force
This is where most extrications begin! Gaining access by using the spreader to pry the vehicle doors open requires the tips of the spreader to start at their weakest position, or Lowest Spreading Force (LSF). As the spreader opens it gains leverage and the spreading force increases exponentially. The problem is that as the vehicle door begins to separate it actually requires less force to continue to open. Therefore, the most important force when choosing spreaders is actually the NFPA 1936 “LSF” rating number.
More Power Up Front
What does “Power Up Front” mean? It means Genesis spreaders have more power at the beginning of the spread, where you need it most. Genesis Spreaders start at a much higher spreading force than our competition. This is critical when choosing a spreader, because it gives rescue personnel more power when starting the extrication.
Published NFPA Numbers
When choosing rescue tools, NFPA has done much of the work for you. Genesis publishes the NFPA 1936 test results for all our tools, certified by TUV, our third party testing organization, recognized by NFPA. We test all of our equipment which lets our customers compare any of our tools performance against other NFPA certified rescue tools. This practice allows departments to compare rescue tools on and “apples-to-apples” basis.
Maximum Cutting Force
Maximum cutting force is NOT an NFPA number. Why? If you look at the illustrations below, you will see two sets of blades. One set is just about to close completely. The other set has overlapped. maximum cutting force is a calculated force, not a measured force. Therefore maximum cutting force depends on where the blades are when you calculate the force generated. You can calculate the force when the blades just start to close (Example 1), or you can calculate the maximum force when the blades have stopped moving and overlap each other (Example 2). Genesis Rescue chooses to provide end users with a realistic cutting force, as opposed to claiming our tools cut at a maximum force, that is only obtainable after the material has been cut. The NFPA standard realizes this and therefore has developed a real life test that enables them to test tools on an even basis.