Fitzer instruments [india] provides vibrating fork level limit switch. The vibrating fork level limit switch is made of stainless steel and kept in mechanical vibration at the resonance frequency by piezo ceramic elements. The fork is either side or top mounted on the vessel. When the service material covers the tines of the fork, vibrations are damped. This is sensed electronically and processed signal is used to energise a relay whose contacts in turn are used for annunciation or control. Two basic types of constructional arrangements are available includes: one, the electronics is separated from the fork, whereas in the other, it is integrated. Mounting arrangements of the screwed or flanged type conforming to various standards, high temperature versions up to 2000c without the necessity of elaborate cooling arrangements and flameproof versions for hazardous areas are also available. Longer probe lengths use pipe extensions made of gi or ss as required. Integral versions meant for high temperature operation are provided with a stand off arrangement for keeping the electronics in a relatively cooler environment. Adjustable probe length types are provided with gland arrangement for making length adjustments.
