Our question: Do you know which load your hail protection net can withstand?

Our motto: Your safety is our job!

In cooperation with the German University of Applied Sciences for Textile Technology and Design at Hof and the Saxon Institute for Textile Research (Sächsisches Textilforschungsinstitut e.V. (STFI)), the physical limits of the patented CMG hail protection net system with zip fastener were tested according to current European standards.

The task was not only to test the system of the zip net, but also to test the individual components such as zip, seams, hail protection net and slider.

The results with regards to the known values, but also the expected values, were remarkable.


The contents of the test:

The determination of the force-elongation behavior of the nets by means of the “FULL SCALE TEST” produced findings and measured values which had not been proven to date for hail protection nets, since here the Italian Uniplast standard for determining the force-elongation behavior of monofilaments simply tests the load on the weaving thread. What is new now is the knowledge of what hail load such a fabric (hail protection net) really withstands. Previous experience was usually based on estimates and observations after hail events.


The tests:

By means of the above-mentioned standards, extensive tests were carried out on the monofilament, the net, the seam, the zip tape and the zip fastener.

After all the above-mentioned individual material tests with extremely positive results, the system test now came with the “FULL SCALE TEST”. For this purpose, the CMG hail protection net with zipper was frictionally clamped in a special frame of 3.00 x 3.00 m. The zipper was placed in the middle and thus ran exactly over a plastic hemisphere with 500 mm diameter, which was mounted on a servo-hydraulic cylinder. With a defined force, the hydraulic cylinder now moved upwards – like a large truck tipping its tons of heavy cargo. This extreme stress ran at 200 mm per minute and ended with a loud bang at a lifting height of 81.4 cm.


The results:

What happened? The hail protection net on the zipper was torn after a load of 6.3 kN or 630 kg.

Now it was the turn of the CMG zip, the heart of the protection system!

With an average value of 3.9 tons after three lateral tensile tests according to the standard, the high safety in a hailstorm event was confirmed.

Here it must be said that this type of net testing is also used for safety nets in air freight.

In the picture (on the right side) a snapshot of the “FULL CRASH TEST” shortly before the crash of the test net.



Successful CMG- net and system test: DIN/EN/ISO 10319, 10321, 2062, DIN/EN 16732

What has been for the fruit grower, farmer, parking lot operator up to now rather a matter of faith and also a matter of trust to their system supplier in hail protection, is now, with the CMG net system in the test bench, for the first time in the history of hail protection nets clearly defined.

We keep what we promise. Safety is Quality!

Georg Gallmetzer


Next Issue:

In the next issue we will report the static loads of orchards with CMG hail protection nets in relation to wind loads: “From a mild summer wind to a thunderstorm! What holds the construction with net and only the net?”