How to choose the best spreader for your department
There’s a lot of misinformation about spread specs, here are the facts.
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By Dalan Zartman for FireRescue1 BrandFocus
Your Department has outdated spreaders and you’ve been tasked with scheduling demonstrations and specing out the future of extrication for your community. This can be a daunting task and often results in frustration and disillusioned rescuers. Cutting through all of the marketing material and sales pitches can be really challenging. But knowing these standards and guidelines will empower you to be an informed end user and make the right purchase.
NFPA 1936 (2015 ed.) is the standard that establishes minimum performance requirements for powered rescue tools and components that are used for extrication. Anyone and everyone who manufactures powered rescue tools and wants to compete in today’s market will adhere to the content of this standard. Here are the basic categories in NFPA 1936:
- Labeling Information
- Design Requirements
- Performance Requirements
So how do we interpret this standard and what do we focus on? It appears on the surface that spreaders with an NFPA certification would be relatively equal, but this is not the case. An NFPA certified tool has endurance tests, drift tests, drop tests, relief valve tests, and on and on. These are all common Pass or Fail criteria that every tool must meet to complete the certification process. However, the testing process also evaluates the specific spreading and pulling forces specific to the tool tested. This generates a “report card”, basically, that can be applied to determine the variance in performance between tools.
This is how to decipher the NFPA spreader report card:
Tool Demographics will provide you with a baseline
Look at characteristics such as weight, length, height, width and spreading distance as a starting point. Not only does this help establish the range of size and spread distance between manufacturers, it develops a baseline for size to strength relationship. Trucks with heavy pay loads are typically bigger and heavier. Trucks with speed and efficiency are typically smaller and lighter with smaller payloads. Finding the right balance for your rescue team between tool dimensions and weight as well as power is essential. If you utilize window spreads and dash lifts as primary techniques, a large spreading distance is vital. If you are a small organization with small statured individuals, weight may be an important factor.
Spreading Force is where the real numbers are
Max force numbers are a thing of the past. Most of these stand-alone big force numbers were predominantly engineering calculations that didn’t always translate to the working ranges of the tool.
What you do want to look for is spreading force. To determine these numbers, a minimum of 10 points on the spreader arms must be measured throughout the working range or arc of the arms. Each one of the ten points must generate a minimum of 2,000 lbf. From the closed position, to at least 95% of the open position, the resultant force is recorded as follows:
- LSF (Lowest Spreading Force): From all ten points, this is the lowest number calculated during the spreading test.
- HSF (Highest Spreading Force): From all ten points, this is the highest number calculated during the spreading test.
These two numbers will tell you what the tool is capable of spreading when the arms are closed and in their lowest or weakest position and when they are open and in their highest or strongest position.
Although the actual number may not mean much to you, it can be compared to that of other spreaders you are evaluating to see which ones are stronger than others in the positions that matter most. Many will agree that the LSF is the more important number because it is where most of our extrication work gets done when we are placing closed tips to pop doors, sheer relief cuts, and lift dashes.
Pulling Force is also an important factor
The exact same process is applied to determine pulling force, just in the opposite direction. 10 points are measured from at least 95% open to the closed position. Each one of the ten points must generate a minimum of 1600 lbf. These calculations are recorded as follows:
- LPF (Lowest Pulling Force): From all ten points, this is the lowest number calculated during the pulling test.
- HPF (Highest Puling Force): From all ten points, this is the highest number calculated during the pulling test.
Pulling Forces are important comparative numbers for squeezing structural materials to reduce cuts as well as using chain attachments to pull materials towards an anchor point. Although this practice has lost much of its prominence over the last decade, it is still an important option for users still deploying it.
There’s no replacement for field performance
Put the spreaders to the test on real cars not bay floor demonstrations without real resistance. Speed is one of the last factors to discuss. Often, speed can’t truly be assessed until you work the tools. There are a lot of variables that affect speed including power source and pump/tool design. Regardless, when we need to get victims freed from entrapments, speed can be just as important as power.
Other selection factors include a myriad of preferences: operating control design, maintenance requirements, cost, tip design and options, compatibility with apparatus and existing tools, etc. All of these other factors become icing flavors once the key ingredients of the cake are chosen.
Weighing your options
To recap, start with the tool demographics. Look at the manufacturers side by side for weight, size, and opening dimensions. Then move to the performance testing. Focus on HSF, LSF, HPF, and LPF. This allows you to see, tool to tool, how they are pulling and spreading. Now that you have a solid understanding of the tool’s capabilities, you can move on to ergonomics, power source, maintenance, and all of the other possible deciding factors. Be an informed consumer and stay up to speed with NFPA standards, industry trends, and new technologies to get the best results for your department.
About the Author
Dalan Zartman is a technical-rescue curriculum subject-matter expert for the Ohio Emergency Management Agency and Department of Homeland Security. He has also taught more than 100 technical-rescue courses at Bowling Green State University, where he serves as regional training program director and advisory board member. Zartman is a member of and instructor for the Central Ohio Strike Team and the Washington Township Fire Department. He is a certified rescue instructor, rescue technician level II, fire instructor II, firefighter and EMT. Zartman is founder and president of Rescue Methods. You can reach him at Dalan.Zartman@FireRescue1.com
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