Chemical production is an important component of a country's industrialization process, involving various aspects of national production. The production process of chemical enterprises requires various detection and control instruments, which are divided into pressure, liquid level, temperature, flow rate, and other categories according to the measurement content. This article will explain the simple principles and selection considerations of relevant instruments based on practical cases encountered in the production of chemical enterprises.

1、 Pressure transmitter

The selection of pressure transmitters varies depending on the application field, process pipeline and equipment structure, opening situation, installation location, medium, temperature and other parameters. But they all convert the measured pressure values into digital signals and transmit them to the control center. It is recommended to consider the selection of pressure transmitters based on principles such as universality and wide applicability, in order to reduce the inventory of spare parts.

2、 Selection of temperature instruments

3、 Selection of flow detection instruments

The flow meters used by the company include: rotor flowmeter, vortex flowmeter, electromagnetic flowmeter, turbine flowmeter, etc. Electromagnetic flowmeter utilizes the principle of electromagnetic induction and can be used to measure the volumetric flow rate of conductive liquids such as acids, bases, salts, etc. Rotary flowmeter is a flow measurement instrument based on the principle of seasonal flow in fluid flow. Rotary flow meters require fluid to flow from bottom to top and can be divided into two types: local indication and remote transmission. The vortex flowmeter utilizes the principle of fluid oscillation for measurement by inserting a non streamlined column into the fluid and using a Karman vortex array for measurement. He can measure the flow rates of gases, liquids, and vapors in pipelines, but he cannot be used in conditions with severe vibration. The characteristics are high precision, wide range, no mechanical wear, and easy maintenance.

4、 Selection of liquid level detection instruments

There are various types of liquid level instruments to choose from for measuring liquid levels based on working conditions and measurement requirements. Including magnetostrictive level gauges, ultrasonic level gauges, radar level gauges, differential pressure transmitters, radio frequency admittance level gauges, magnetic flap level gauges, etc. Magnetostrictive level gauges are mainly used to measure the liquid level of chlorosilane storage tanks, while radar level gauges with waveguide cables are mainly used to measure the level of silicon powder storage tanks in solid and liquid-solid mixed conditions. Differential pressure transmitters mainly measure the liquid level of non corrosive media. Instruments for measuring liquid levels can be classified into differential pressure, buoyancy, electromagnetic, nuclear radiation, acoustic, optical, and other types based on their working principles.