g-max Testing of Artificial Turf
Artificial turf fields are typically tested in
accordance with ASTM Standard F355-A and Specification F1936.
- Standard F355 regulates impact
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
test point locations for a number of sport-specific field
configurations. It also includes a protocol for dealing with
||Suggested Test Points for a Football Field
- 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.
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.
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:
Click here to view a sample specification in pdf format. (You will need Adobe Reader to view this file.)
- 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
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