The web´s fibre strength is measured with the Zero Span Test. Using an initial gage length near zero, a tensile test is performed. Now, mainly the pulp fibres are loaded.
The Zero Span Test is usually performed with dedicated instruments, being accordingly complex and expensive. If Zero Span Test are not frequently used, Zwick´s modular system of grips and accessories offers an affordable solution: For an exact horizontal and angular grip alignment, Zwick offers a mechanical extension kit. The grip already must despond to some minimum accuracy requirements, which is achieved by pneumatic grips.
The Zero Span jaws protrude from the grips inner edge and allow a free span of approximately 0.1 mm. This can only be achieved with numerically controlled machine such as Zwick´s ProLine or zwicki-Line, which guarantee best reproduceability and reduce the risk of danger to a minimum.
For this test the TAPPI T 231 is the Standard.
