Industrial Level Measurement and Detection Systems

Capacitive Level Meters

Electric Meters radiation level 2: Capacitive meters measurement is based on the variation of capacitance, which changes when the dielectric medium between its plates varies. Capacitance is influenced by three primary factors:

• 1. Distance between electrode plates.
• 2. Size of the electrode plates.
• 3. Dielectric value of the material between the electrodes.

The capacitance change makes the oscillator operate at a level proportional to the measurement.

Vibrating Level Switches

Vibrating level switches are polled as a tuning fork vibrating via a piezo-driven 80Hz signal. If the substance covers the pitch, the signal is damped, which produces a signal that activates a relay. It is used for both liquids and solids of small particle size, as well as pulp.

Optic Level Switches

Optic level switches consist of a light source and a photocell. When the substance reaches the light beam, it does not reach the detector, and the output switches. These are used in the detection of foams, interfaces, water, and sludge.

Temperature Level Meters

Temperature meters are used with very viscous fluids and high temperatures. This method consists of placing various thermocouples or temperature gauges at different heights in the container where we aim to measure the level. As the fluid rises and comes into contact with the thermocouples, they detect the temperature change and provide an indication of the level.

Sound and Mechanical Detectors

Diaphragm Detectors

A diaphragm detector consists of a flexible membrane that may come into contact with the product inside the tank. It contains a set of levers with a counterweight that rely on a microswitch. When the level of solid material reaches the diaphragm, the strength acts against the counterweight, beating an alarm.

Suspended Cone Sensors

A suspended cone is a microswitch mounted inside a watertight box with a rubber cup that is suspended from a rod ending in a cone. When the solids level reaches the cone, the switch is excited. This is used only in open tanks. It is inexpensive but needs to be protected as its precision is low (+/- 50mm).

Flexible Rod Switches

A flexible rod consists of a steel rod attached to a brass diaphragm which contains a switch. When solid pressure acts upon it, the switch closes and acts upon an alarm. It is hermetically sealed and is used as a high-level alarm in open tanks. Its precision is +/- 25mm.

Conductive Level Meters

A conductive meter is provided with an electrode inside earthed plates with the circuit open. When the solids reach the device, it closes the circuit and the current is amplified, acting on an alarm relay. The solids must have conductivity for this system to function.