1.6 Service

» Because of the hygroscopic characteristic of the used ceramic insulation materials they absorb mois-ture. Therefore we send our cartridge heaters usually in air-tightly closed plastic bags. When stored unprotected in environmental air it is absolutely important to check the insulation resistance before use and – if necessary – to dry the elements (controlled start-up or drying oven).

» Bending the outside connection points (exit type N) could break the termination and must be avoided.

» The temperature stress of max. 750°C at the sheath is not valid for the connection area. The temperatures arising in the connection area determine decisively the suitability of the available exits.

» The stated nominal voltage must not be exceeded, otherwise overheat is risked.

» Generally it can be said: the better heat is carried off, or flows into the work piece respectively, the higher the surface watt density on the sheath can be.

» Watt densities on the cartridge sheath of up to 50 W/cm² are acceptable only controlled and in ideal thermal installation conditions. Materials with a good thermal conductivity and a narrow tolerated car-tridge heater fit are therefore recommended strongly.

» For our h7-ground high density cartridge heaters we recommend H7-holes with a surface roughness as small as possible.

» Form errors of the hole, crossing holes or shrinkage cavities obstruct the heat conduction and lead to heat accumulation which could partly overheat the cartridge critically.

» The connection area of cartridge heaters must be protected from lubricants, detergents and solvents, because these could diffuse into the ceramic and lead to short-cuts.

» In every practice application there are working and environmental parameters which can not be calcu-lated exactly in theory. That is why we recommend generally to test cartridge heaters in the application under real working conditions in advance.