Weldable strain gage WTN series

dynamic

Weldable high temperature strain gages are dedicated for measurements of deformations in the details of machinery and equipment under dynamic loads in ‑269…+900°C temperature range. These gages are intended for installation in places where bonding with ceramic cements is not possible either due to complication in surface preparation (polishing, degreasing, etc.) or due to large dimensions of the test object (cannot be thermally treated for cement curing). Construction-wise a WTN series strain gage is a STN series wire strain gage, installed on a small piece of thin metal foil with ceramic cement and protected with organosilicon varnish. Sensitive grid of the gage is made of 20…30 um diameter nickel-chromium wire. Backing material is an oxidation and corrosive resistant nickel-chromium superalloy. This material is selected to match the thermal expansion coefficient of the sensitive grid. Sensitive grid is installed on the backing using high temperature ceramic cement, applicable for long-term operation at 900°C. Ceramic cement also acts as an insulator layer between backing and the grid. Cement layer is protected against humidity with an organosilicon varnish. Lead wires are made in a 2-core chromel/alumel cable in silica braid sheath. Typical diameter of the cores is 0.3 mm, but can be changed on demand. Typical length of the lead wires is 100 mm.