TESTING

Testing to ASNZS 4422 - 1996

The Standard has been amended - Amendment 1: 1999 - with respect to some technical aspects of the testing. 

Some pertinent points of the Standard, which is available from Standards Australia

can be summarised as follows

Scope : The Standard gives the general requirements for surfacing to be used in children's playgrounds and specific requirements for areas where impact energy attenuation is necessary. This testing prescribes a critical fall height for a surface, which represents the upper limit of its effectiveness in reducing head injury.

HIC
The Head Injury Criterion is a measure of the severity of an impact and takes into account its duration as well as its intensity. The criterion is based on the results of research into the effects of impacts on the human head. HIC is defined by the following integral formula

 G-max
G-max is the maximum deceleration experienced by the head (or headform) during an impact. It is a measure of the peak forces that a likely to be inflicted on the head as a result of the impact. It is measured in units of G, acceleration due to gravity - 9.8 m/s/s.

Critical Fall Height
The minimum free fall height resulting from all test drops of an instrumented head onto a surface for which an HIC equivalent of 1000 or a G-max value equivalent to 200 is obtained.

Impact attenuation requirements
The impact attenuation requirements of surfaces or surfacing materials should be certified by the following means:

Laboratory testing : The critical fall height for each material or combination of materials shall be determined.

On-site testing : The critical fall height of the surfacing material within the fall zones of equipment or structures shall exceed the free fall height for each item of equipment.

Loose fill materials : Loose fill materials eg bark chips, will deteriorate and be dispersed in use. To allow for this deterioration an additional 50 mm of material described in a test report shall be installed. A minimum depth of 200 mm is required.

Specific requirements for impact attenuation :
Fall heights up to and including 500 mm : surfacing (impact absorbing) may be used without being tested
Fall heights over 500 mm : For playground equipment with a free fall height of greater than 500 mm, surfacing which gives a critical fall height equal to or greater than this height is required in the fall zone.

Equipment:
Drop system: Free fall to use tri-axial accelerometers. Guided fall to use a co-linear uni-axial accelerometer and timing gates for measurement of impact velocity.

Headform : Size J headform as specified in ASNZS 2512.1 with a mass of 5.0 +/- 0.1 kg

Accelerometers and signal processing equipment : Shall conform to channel class 1000 of ISO 6487

Testing

Loose fill materials : 3 impact drops from the same height are required at each test position.

Non deformable materials : a minimum of 4 drops required at each of 3 or more positions representative of a typical installation of the material.

Processing : Graphs shall be drawn of Fall Height versus HIC, and Fall Height versus G-max. The critical fall height is determined from the graph using the HIC = 1000 or G-max = 200 criterion.

The Laboratory can be contacted to arrange this testing by fax, telephone or email..

For product certification duplicate sets of samples should be delivered. The dimensions of the samples will depend to a large extent on their type - tiles, in-situ cast materials, continuous roll materials etc. and the exact requirements should be ascertained from the Standard or discussed with the Laboratory. For bark chips and other loose fill materials approximately ten 50 litre bags are required.

In-situ testing of installed materials can be done in the Sydney metropolitan and surrounding locales. More remote testing site-testing can be done at cost.