Single Point Level Switch For On-Off Control Of Liquids
- 4mA,20mA Output
- Intrinsic safety
- Hermetically sealed
The Sonac© 110 provides the most reliable overflow alarm or control available.
Where liquids to be sensed constantly change physical or electrical properties. The Sonac© 110 principle of measurement is used with extremely small vessels or pipes and when little or no intrusion into the process is required.
Non-dedicated vessels – liquids
The device senses virtually any liquid and does not need adjustment when the density or dielectric constants are changed.
High temperature, High pressure service
The welded, all stainless steel sensor body is designed for service at temperatures to 220°F (+104°C) and pressures to 2,000 psig.
Fluids with foam blankets
The control ignores foam to indicate the true liquid level.
Principle Of Operation
The sensor is a magnetostrictive device consisting of a diaphragm, nickel tube, magnet, drive coil and pickup coil.
When 40 kHz energy is applied to the drive coil, it causes the diaphragm to vibrate at a frequency determined by the mechanical resonant system of the sensor. Electrical energy is transferred to the pickup coil when the diaphragm is free to move in gas. When the diaphragm motion is loaded by a process material, less energy is transferred to the pickup coil.
The pickup coil of the sensor is connected to the input of an amplifier and the output of the amplifier to the drive coil to form a feedback loop circuit. Any energy appearing in the output of the sensor will be fed to the amplifier, amplified and returned to the input of the sensor. This causes vibrations at 40 kHz to occur in the diaphragm and furnish a signal back to the amplifier for reamplification. When the gain of the amplifier is adjusted so as to exceed the losses within the sensor, continuous oscillations are produced.
If the diaphragm of the sensor is exposed to a process liquid product which offers greater mechanical resistance to the motion of the diaphragm, the transfer of energy to the pickup coil decreases. This results in a decrease in the signal feedback into the amplifier and a corresponding decrease in the signal available from the output of the amplifier. The decreased signal triggers a voltage sensitive network that controls the output relay.
A unique AUTO TEST self-checking circuit constantly verifies the integrity of the sensor circuits. The RED LED is illuminated when the product is absent at the sensor and the system is oscillating at approximately 40 kHz. If the amplitude or the frequency of the sensor circuits changes, the RED LED will go out. If the change of state occurs due to a level change, the relay will follow and change its state. However, if the change of state is due to a sensor failure or some other component failure, the relay will immediately transfer to the alarm condition. This foolproof feature protects the system for loss of power, major component failure or damaged sensor conditions. The Sonac© 110 system will fail-safe for all sensor or component failures except for open sensor.