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Introduction - Flow Sensors

Introduction

Classification

Functions

Precautions for
prorer use

Introduction

Principle of operation

The flow sensor measures the amount of gas or liquid that is flowing over a certain amount of time.
Sensor system is divided into: Volume flow sensing and Mass flow sensor systems.
Especially the gas flow sensors used in FA mainly uses a Mass based system, within which there are three other systems: the Heated system, Coriolis system, and the Vortex system.

Flow sensors	Volume flow system
	Mass flow system	Heating system
		Coriolis system
		Karman vortex system

Panasonic Industrial Devices SUNX's flow sensor uses the heating system mass flow system.

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Heating system flow sensor principles and characteristics

Panasonic Industrial Devices SUNX's heating system flow sensor uses a silicone sensor chip made with silicone micro manufacturing technology.

The heater inside of the silicone sensor chip is insulated against heat from the main silicone board, so because the about of heat is so small it is incredibly sensitive and quick.

If the bridge circuit is set up as below so that the heater and ambient temperature sensor are on the bridge circuit, then the temperature difference between the ambient sensor and heater will be kept constant by the control system.
The heater is made from platinum because of its proportionate resistance values to temperature changes.

When dealing with gas flow the heater must be kept at a constant temperature, so the heat that is taken from the heater is proportionately replenished with voltage from the bridge circuit.

Using this control system the sensing of the flow rate can be protected from the influence of temperature and pressure changes. Also, this control system can be used for comparatively high flow rates.