SATRA STM 510 leakproofness tester

How to test rubber or moulded boots for their ability to prevent water ingress.

by Peter Allen

SATRA’s STM 510 leakproofness testing machine allows a test to be carried out which is specified in a number of European safety footwear standards – for example, EN ISO 20345:2011 (personal protective equipment-safety footwear). The test applies to footwear classified as Class 2 – with a closed seat region. These are boots defined as either all-rubber (entirely vulcanised) or all polymeric (entirely moulded). The test is specified in EN ISO 20344:2011 clause 5.7 (determination of leakproofness), and examples of footwear for which this test is applicable include half-knee boots or knee-high wellington style boots, although a number of other styles and types can also be tested for leakproofness using the STM 510 machine.

The test is relatively simple to conduct. The opening of the footwear sample is sealed and an air feed is introduced inside the boot through the opening seal plate. The test piece is then immersed into a water bath up to the top edge of the boot and an internal air pressure applied to the footwear sample (in the case of EN ISO 20344) at a pressure of 30±5kPa, and maintained for a period of 30 seconds.

During this immersion period, the footwear sample is observed to see if there is a leak, indicated by air bubbles. To comply with the standard’s requirements, air leakage should not be detected.

STM 510 features

The SATRA STM 510 leakproofness testing machine incorporates a number of features which aid the conduction of this test. Provided with the test machine are a range of seal plates with associated external clamps, which allow the top of the footwear to be sealed. The different sizes of seal plates allow the accommodation of different footwear opening sizes.

The test machine is connected to a compressed air supply, which is regulated and fed through a pipe and coupling in the seal plate to apply an internal air pressure to the footwear. The footwear is mounted in a frame which incorporates a means of support and attachment to secure the footwear. The machine also contains a means of lowering the footwear under the water in the water bath. The footwear support frame and lowering and raising feature of the STM 510 test machine give a distinct advantage in retaining the footwear in a fixed position when immersed, which prevents it floating within the water bath. The STM 510 water bath has transparent side panels, so improving the visibility of the test specimen when inspecting for air bubbles, which are indicative of a water leak.

In addition to conducting leakproofness tests as described, this test machine can also be used to audit test the leakproofness of production samples during footwear manufacture. The test is simple to conduct and of only a short duration, so will be suitable to use when checking completed footwear from a production line. This would allow any production faults which resulted in a water leak to be located. A rectification of the problem could then be carried out before a significant volume of the product had been made.

Another SATRA test machine which can be used to assess the water resistance of this type of footwear is the SATRA STM 184H high water whole shoe flexing machine. This is used to assess the water resistance of rubber or moulded footwear when repeatedly flexed under water, simulating the flexing introduced while walking. SATRA also produces a wide range of other test equipment suitable for conducting tests as specified within the requirements of EN ISO 20345 and other European safety footwear standards.

Click here for comprehensive information on SATRA's range of test equipment.

Publishing Data

This article was originally published on page 36 of the May 2013 issue of SATRA Bulletin.

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