Gasket Compression Calculations for Pressure Transducer Port Glands
Optimizing transducer port sealing demands balancing 15 to 25 percent gasket squeeze against volumetric fill below 85 percent to prevent mechanical die offset.
Shore a Durometer
Hardness Assessment
Mechanical indentation instruments measure the resistance of vulcanized rubber and soft plastics to penetration by a standard foot. The Shore a durometer uses a hardened steel rod with a truncated cone profile to evaluate material hardness. This measurement determines the compliance of seals and flexible tubing.
Higher readings indicate a stiffer material that is more resistant to extrusion.
Indentor Motion
Spring loaded forces apply pressure through the indenter to the surface of the specimen during the measurement. When using a Shore a durometer, the indenter must be pressed flat against the sample with a constant force. The depth of penetration is converted to a hardness value on a scale from zero to one hundred.
Measurements must be taken at least six millimeters from any edge to ensure accuracy.
Calibration Precision
Calibration of the spring force and indenter geometry is performed using certified reference blocks of known hardness. Force testing utilizes a dead weight fixture to verify that the spring complies with the specified force deflection profile. The indenter height must be measured with a high accuracy micrometer to ensure the tip protrudes by exactly two and a half millimeters.
Environmental conditions like ambient temperature and humidity must be controlled because elastomer hardness changes with temperature. The test certificate must detail the measured spring force and the tip geometry.
Material Reaction
Viscoelastic creep in the polymer causes the hardness reading to decay over the first few seconds of contact. Handheld testing introduces user variation in the speed and force of application, so using a stand improves repeatability.