A window or door element has to be able to withstand pressure from within or without, because otherwise manufacturers are not allowed to affix a CE marking to their product and thus cannot sell it in the EU. Such tests are carried out by the Schösser und Beschläge Velbert (PIV) testing institute. These are carried out in accordance with the DIN EN 14351-1 standard, which has applied to the performance characteristics of windows and exterior doors since 2006, or in accordance with DIN EN 13830 for facades. The test includes testing for air permeability, driving rain resistance and wind load.
Air permeability testing
Gütegemeinschaft Schlösser und Beschläge
First, the test bench is prepared and the element is mounted. Then the four-hour test begins. The function of the test specimen is checked in advance: the element is opened and closed at least five times. This is followed by three pressure surges with maximum air pressure, which in this case is 660 pascals (Pa). This corresponds to almost 120 km/h and thus reaches hurricane strength. After that, the actual test begins with a pressure increase in increments of 50 pascals. This corresponds to a light breeze of 35 km/h and moves the branches of a tree in the open air. This should not be a problem for a window or door element. The pressure is gradually increased to 300 pascals. This is equivalent to a storm with winds of almost 90 km/h, which can cause minor damage to the environment. To test market suitability, the pressure is increased from 300 Pa in 150-pascals increments up to 600 pascals. This value corresponds to a hurricane-force storm. The test is then repeated with negative pressure to create an equally strong suction force.
The standard defines four air permeability classes, with class 4 being the highest. To achieve one of the specified classes, the measured air permeability must not exceed the upper limit at a test pressure in that class. Both the air permeability in relation to the total area and the openable joints are evaluated.
Testing for driving rain tightness
Gütegemeinschaft Schlösser und Beschläge
The air permeability test is followed by the driving rain tightness test. First, the element is sprayed with water for 15 minutes without air pressure. If the previous hurricane caused minimal deformation, this would already be visible at this stage. However, according to Gregor Röhling, who has been testing at PIV for 16 years, this hardly ever happens. The actual test then begins with increasing air pressure, similar to the air permeability test, until 600 pascals are reached. However, even higher pressures can be tested at the customer's request. The test bench has spray nozzles every 40 centimeters, each spraying two liters of water per minute. “That's quite a powerful spray,” reports Röhling. During the test, the tester observes the element for water leakage. Any abnormalities are recorded.
Wind load testing
If the element remains dry inside after the driving rain test, the manufacturer—who traditionally attends such a test—can breathe a sigh of relief. But the test is not over yet: now comes the wind load test. This test checks whether the element deforms within the permissible range. To do this, the tester attaches measuring probes to the test specimen. These measure whether the deformations during the test are still within the tolerance range. Then there are another 3 pressure surges. The pressure level depends on the class being tested. Depending on the class (1 to 5), the pressure P1 is 400, 800, 1,200, 1,600, or 2,000 pascals. However, higher pressures can also be tested here at the customer's request. The three pressure surges mentioned above are performed at a pressure of P1+10%. This is followed by a gradual pressure increase in 400 Pa increments up to P1 of the respective class, which is held for 30 seconds. The deflection is then measured.
Gütegemeinschaft Schlösser und Beschläge
After the pressure has been reduced, the deflection is checked again one minute later without wind load in order to detect any permanent deformation. The test is then repeated with negative pressure. In the second half of the test, 50 cycles are performed with alternating positive and negative pressure, each at half the P1 pressure. Finally, a safety test is performed: Here, the element is loaded with 1.5 times the maximum pressure. It may deform more than specified in the standard, but must remain intact.
Now the evaluation takes place: “We examine the test element for damage or loose parts. We enter all findings in the report. Our software then evaluates all the data collected and the customer receives the documentation, the report, and in most cases also the positive test result,” says Röhling.
