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g-max Testing of Artificial Turf

Standards for Testing
Artificial turf fields are typically tested in accordance with ASTM Standard F355-A and Specification F1936.
  • Standard F355 regulates impact attenuation testing on playing surface systems and materials. It describes basic test procedures and reporting requirements. Procedure "A" of Standard F355 (F355-A) defines equipment requirements for impact attenuation testing on turf. 
  • Specification F1936 prescribes procedures and reporting requirements for impact attenuation tests of turf playing systems. By reference, it incorporates the equipment requirements of Standard F355-A. The Specification includes diagrams of suggested test point locations for a number of sport-specific field configurations. It also includes a protocol for dealing with multi-sport fields.

Suggested Test Points for a Football Field
Side D
End A
End B
Side C

    • Note: Test points #7 and #8 are selected by the person performing the test. Test point #7 can be located anywhere between the inbounds lines and the "limit lines" of the field. Test point #8 can be located anywhere within the "limit lines," to include the field of play.

Test Procedures
The basic testing procedure requires three g-max readings at each test point. The readings are taken at one-minute intervals. The values from the second and third readings are averaged, to determine the g-max rating for the test point. Additionally, the air temperature, the temperature of the infill material, the height of the carpet pile and the depth of the infill are recorded at each test point. General weather conditions, including relative humidity, are recorded for each day of testing.

When testing is conducted on an annual basis, it is important that the orientation of the test points be the same from year to year. In other words, "end A" should always be the same end of the field. This facilitates the comparison of results from one year to the next.

The results of the test are summarized in a comprehensive report which indicates whether or not the field meets the g-max requirement established in Specification F1936. The details of individual g-max readings are included in the report, so that owners, or their representatives, can evaluate the performance of the field against more restrictive g-max requirements that may have been written into the specifications for the field.

g-max Performance and Testing Specifications
Where synthetic fields are concerned, many factors will influence the ongoing performance of a field and the owner's and users' perceptions of that performance. Arguably, one of the most important is the quality of the project specifications that address g-max performance and testing. A well crafted specification will define reasonable performance expectations that protect the owner's interests, and, at the same time, are fair and achievable from the perspective of the manufacturer/installer. A good specification will also clearly define the testing required to provide ongoing assurance that a field is meeting its g-max performance criteria.

The key elements of an effective g-max specification include:
  • g-max performance requirements during the warranty period -
    • An upper g-max limit is essential, and should not exceed 200g's.
    • A lower g-max limit is optional.
    • Additionally, the specification can include a separate g-max requirement for initial acceptance of the field - criteria to be met prior to the time the field is put into use.
  • Procedures for dealing with situations where the field fails to meet a g-max performance requirement -
    • These procedures should recognize that the manufacturer/installer shouldn't be held liable for certain types of problems, once the field has been accepted and put into use.
    • They should also specify when a retest is required to verify that a problem has been corrected.
  • A requirement that all g-max tests be performed by an independent lab or testing service
  • A requirement that all g-max tests be performed in accordance with ASTM Standard F355-A and Specification F1936
  • A firm schedule of when g-max testing is required
  • Clarification of who is responsibile to schedule and pay for the g-max tests
  • A requirement that the owner be furnished copies of all g-max test reports
Click here to view a sample specification in pdf format. (You will need Adobe Reader to view this file.)

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g-max Testing Guides
Sports Turf Solutions has published a pair of informative pamphlets: "A Guide to g-max Testing" and "Getting the Most from a g-max Test." They are excellent sources of basic information about g-max testing, and should be of interest to anyone who owns, manages, maintains or uses synthetic fields. Call, write or e-mail, to request your free copies.
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