An Explanation of the New ASTM F3351 Test Method for Specified Height and Why It’s Important

ASTM F1292 has been a safety standard since the early 90s. It tests for the critical fall height (CFH) of a playground surface. Recently, ASTM International brought about some changes to this familiar playground surfacing standard, and everyone in the industry should know about these new requirements.

What Is Critical Fall Height (CFH)?

CFH is calculated by impact testing a safety surface with a device known as a Triax impact tester. The Triax uses a head form that, when dropped on the surface, reports measurements of how well the safety surface absorbs the impact. Those measurement readings are in a unit of measure known as a G and something called Head Injury Criteria (HIC). The max G that a surface can have is 200, while the max HIC allowed is 1,000.

The surface is tested to the point at which it fails. So if you ask for an ASTM F1292 test result, you will find three readings on the report — the height at which the surface failed, the CFH (the maximum height before the surface failed the test) and a foot under the CFH. The sample will also get tested at three temperatures — 25 degrees Fahrenheit, 70 degrees Fahrenheit (ambient) and 120 degrees Fahrenheit.

For example, if you desire a poured-in-place rubber surface for your 8-foot playground equipment, you should ask for a copy of the certification from your vendor. The vendor will show a certificate along with the test results, proving the laboratory tested the vendor’s 3.5-inch PIP system.

In this case, the results show that the CFH was 8 feet, giving results of 190 G / 996 HIC while testing at 25F. The results also showed readings at 9 feet- 204 G / 1056 HIC, the point at which it failed,  and results at 7 feet- 170 G / 845 HIC (one foot below the determined CFH) required by the F1292 specification.

As a playground owner, you may wonder:

What happens when temperatures plummet?

What happens when the rubber in the surface gets old and begins to be less resilient in a few years?

If I ask the vendor to install this system showing a CFH of 8 feet around my play equipment, with a Gmax reading of 190 and a HIC reading of 996, do I have room for error without risk of serious injury?

Wouldn’t it make sense to ask for a playground surfacing that performs at much lower G and HIC values for the specific height of my playground equipment so that there is room for variables such as temperature, usage and age?

The New Era Begins — ASTM F3351 Test Method for Specified Height and ASTM F3313 for In-The-Field Testing

Before we answer the previous questions, let’s use the following metaphor of stopping a wagon from going off a cliff. We will think of the distance from the wagon to the cliff’s edge as being the HIC criteria on a playground. The farther away from the 1,000-foot edge (1,000 HIC) we are, the less likely a serious injury will occur.

If the wagon is going down a hill and a severe, life-threatening injury occurs 1,000 feet down the path, would you want a choice of either stopping at 700 feet before the cliff’s edge or 996 feet before the cliff edge? Keeping in mind that the brakes on the wagon are wearing down as the wagon gets older after years of use?

The danger that the wagon is facing is like the scenario you have with your playground. Do you put just enough surfacing on your playground to prevent serious injuries such as the scenario we described above? Or do you install surfacing that performs well under the critical line of danger?

The choice is obvious — you want surfacing that is going to perform well under that critical line of 1,000 HIC and 200 G’s.

But how far under the critical line do you want to be? There is some information from the US National Highway Transportation Safety Administration that could be of some help to answer this question. Their studies have suggested that starting at 1000 HIC the risk of a critical head injury is 3%, 18% risk of severe, life-threatening with survival probable, 55% risk of serious and 85% risk of moderate and 200g is a 10% risk of skull fracture. But as we lower the HIC, we lower the risk. These studies have indicated that if we lower the HIC to 700, for example, we can lower the 18% risk of a severe, life-threatening head injury to 5%! So it’s important for the playground owner to understand, kids will fall and we can’t eliminate injuries totally, but we can reduce the risk of severe injuries by installing appropriate surfacing.

How does the playground owner find out how various surfaces match up with G and HIC values when shopping for playground surfacing?

New ASTM Playground Surfacing Standards

Ask for ASTM F3351 test results — a new standardized test method for playground surface impact testing performed in a laboratory at a specified test height (STH). This new test method allows for laboratory testing at a drop height lower than CFH using the same test procedures as F1292. This means you, as the owner/operator, can be in the driver’s seat. Plus, it requires your safety surfacing to perform better at initial installation with lower HIC and Gmax values than the CFH limit in F1292.

Using our previous example, knowing that we now have the option to require lower HIC and Gmax values, you can require your surfacing to perform at a lower G and HIC. This time, when you ask your vendor for a certificate and test results, you require that the PIP system performs with maximum Gmax and HIC results of 120 G’s and 700 HIC at 8 feet at initial installation.

Additionally, you could require a guarantee not to exceed 180 G’s and 900 HIC for “X” number of years. With this new standard, the vendor will now give you a certificate, test results from ASTM F3351 and a warranty showing their 4-inch PIP system meets or exceeds your performance requirements. Notice the PIP system is now 4″ thick. It may cost more but now you understand that a thicker surface gives better G and HIC readings. This would allow for the surface to still fall under the pass/fail limit of 200 G’s and 1,000 HIC even as it ages.

Trust But Verify

The second element to our example is to require impact testing “in the field” at your playground after installing the surfacing. This verifies that your installed surface meets the criteria you stated in your bid. It can be done by requiring test results from ASTM F3313 — the standard test for determining a playground surfacing’s impact attenuation as tested in the field.

This “new” test method was actually adopted by ASTM a couple of years ago, as of this writing. It was taken from the old ASTM F1292, which had contained information about field testing — but at CFH. This was not useful information since testing loose-fill surfaces, such as Engineered Wood Fiber and Loose Fill Rubber, have CFH limits of up to 17 feet in some cases.

However, most maximum fall heights on many playgrounds are 6-10 feet. ASTM F3313 now requires the test operator to test at the fall height of the playground equipment or whatever the fall height you required at purchase, as long as it’s above the fall height of the equipment.

ASTM Playground Guidelines

When it comes to ASTM playground safety standards, knowing the CFH of a playground surface is not necessarily advantageous. Knowing how the surface performs at a specific test height proves to be more beneficial since you can specify your surface to your particular playground equipment and therefore lower your risk of potential injuries and increase the functional longevity of your playground surfacing.

The ASTM defines fall height as the vertical distance between a designated play surface and the protective surfacing beneath it. Therefore, fall heights will vary based on the type of equipment. You must take the fall height measurements at different points for various equipment types, such as:

• Climbing equipment: The highest part of the climber intended for foot support
• Upper body equipment: The highest part of the equipment
• Swing sets: The pivot point
• Seesaws: The maximum height attainable by the seat
• Spring rockers: The height of the seat
• Composite equipment (equipment with connected components): Distance from the highest designated play surface to the protective surface.

Importance of ASTM Playground Safety Standards

ASTM standards are critical to keeping children safe on your playground. And with an estimated 200,000 children injured in playground falls each year, you must adhere to critical fall height and surface standards. Unless you tested your surfaces and they meet the ASTM-F1292 standard, the children playing on your equipment will be at a higher risk for injury.

Experts continually study and evaluate playground safety as materials and construction capabilities evolve. They also frequently discover new information about how to optimize playground safety. ASTM standards are modified to reflect these developments in capabilities and information, making it crucial that you follow these guidelines.

How It All Works

When purchasing surfacing products from Zeager Bros., Inc., we warranty our products to perform well under the maximum Gmax and HIC requirements written in ASTM standards. Why? So that you can rest assured that our safety surface products will perform well past installation. You can always ask your Zeager salesperson for test results from our various surfacing products to see how they perform in the real world. 

Other benefits of purchasing our surfacing products include:

• Slip resistance: Our materials prevent slips for a reliable surface option.
• Shock-absorbing qualities: You can count on us to follow ASTM playground guidelines for material depth to absorb impact and shock
• Affordable: We offer fair pricing to help ensure all of our customers can afford materials that meet the necessary ASTM playground safety standards.
• Natural and sustainable: We use all-natural materials for safer and more environmentally-friendly options.
• Easy maintenance: Our surfaces are naturally durable and easy to clean and maintain.
• Reliable: We design surfaces with resilient properties to withstand daily use, wear-and-tear and variations in temperature and weather conditions. 

Work With Zeager

We are a leading manufacturer of playground surfaces, and we create all of our materials per ASTM playground safety standards. As a family business, we take pride in offering products that can help children stay happy and safe while using your playground. We offer unmatched customer service and will work with you to find the perfect solution for your playground within ASTM playground guidelines. 

As a top playground surface manufacturer, we have the knowledge and experience to assist you in finding the perfect surface materials for your playground. We know that your playground surfaces are a critical investment, so we do all we can to provide you with the highest quality materials at fair prices. We also offer free quotes so that you know the potential expenses upfront. 

If you have any questions about the information contained in this article or about the products and surfaces we offer, contact us today and we will be happy to help. You can also reach Jeff Mrakovich at Zeager Bros., Inc. 1-800-346-8524 X 246 or email jeff@zeager.com.