EIT LiQlyzer Vibration Fork Level Switch

How a vibration forks level switch operates

Only point level measurements are applicable for vibration fork switches. They are made out of a whirling or tuning fork that vibrates in the air at a predetermined natural frequency. When the fork makes contact with a medium, the vibrates frequency will be decreased.

Operating Principles

A tuning fork switch consists of a two-pronged fork that is often driven by a piezo-crystal assembly to oscillate at its natural frequency. The switch is often installed using a flange or threaded process connection on the side or top of a tank so that the forks stick out into the tank.

The forks' inherent frequency of vibration when in the air is observed by a detection circuit. The level switch's output state changes to operate an alarm, pump, or valve when liquid covers the forks, which is recognised by the switch electronics as a decrease in oscillation frequency. The switch's operating frequency is designed to prevent interference from natural plant vibration, which could result in mistaken switching.

The construction material is typically stainless steel, allowing usage in applications requiring high pressure and temperature, with possibilities for coated wet sides or exotic materials for corrosive applications.

Medium temperature range	-20-220°C
Ambient temperature range	-20-80°C
Ambient humidity	≤95% RH
Medium density	liquid≥0.7g/cm3; solid ≥0.1g/cm3, particular≤10mm
Liquid velocity	<1000mm2/s
Angle of the measured medium	≥200
Pressure range	≤1Mpa
Body Material	aluminium alloy M20 X 1.5
Fork Material	1Cr18Ni9Ti
Waterproof grade	IP65
Connection thread	G1", G3/4, G1 ½, 1”NPT Flange
Power Supply	DC24V ; AC220V 50Hz
Output	PNP, NPN, AC250V/4A, DC60V/4A
Vibration frequency	300±50Hz