Choose the Right Solenoid Valve

Figure 1: Different types of solenoid valves.

Solenoid valves are industrial equipment controlled by solenoids. It is the basic element of automation used to control fluids. It can play an important role in industrial control systems: adjusting the direction, flow, speed and other parameters of the medium. But to give full play to its role, it is necessary to select the appropriate solenoid valve. This article will introduce the four most important principles and six basis of solenoid valve selection.

1. Principles of Solenoid Valve Selection

Safety, applicability, reliability, and economy are arguably the four major principles to be considered first when choosing any industrial equipment. Choosing a solenoid valve is no exception. The following will introduce the specific content of these four principles in solenoid valve selection.

1.1 Safety

1) Corrosive medium: For example, the isolation diaphragm type must be selected for strongly corrosive medium;
2) Explosive environment: choose products with corresponding explosion-proof grades.

1.2 Applicability

1) Media characteristics: different types, temperature, viscosity, cleanliness and flow direction of media;
2) Pipeline parameters: medium flow direction, flow requirements, valve Kv value, working pressure difference and pipeline connection method;
3) Environmental conditions: temperature, humidity, vibration, bumps, corrosiveness, explosiveness, size of operating space;

Figure 2: A solenoid direct acting explosion-proof valve.

4) Power supply conditions: power supply type, voltage specification, voltage fluctuation, power supply capacity;
5) Control accuracy: whether multiple solenoid valves are needed, action time, and leakage.

1.3 Reliability

1)Operating life;
2) Working system: long-term, repeated short-time or short-time working system;
3) Working frequency;
4) Action reliability.

1.4 Economy

Economy is one of the selected criteria, but it must be based on safety, applicability and reliability. It entails not only the price of the product, but also its function and quality, as well as the cost of installation, maintenance and other accessories.

2. Basis of Solenoid Valve Selection

According to the operating conditions in 6 aspects:

2.1 Pipeline Parameters

1) Determine the diameter (DN) size according to the size of the inner diameter of the pipeline or flow requirements on site;
2) Interface mode, generally, flange interface should be selected for >DN50, and ≤DN50 can be freely selected according to user needs.

2.2 Fluid Parameters

1) Corrosive fluid: corrosion-resistant solenoid valve and all stainless steel; edible ultra-clean fluid: food-grade stainless steel;
2) High temperature fluid: solenoid valves made of high temperature resistant electrical materials and sealing materials, with piston structure types;
3) Fluid state: gaseous, liquid or mixed state;
4) Fluid viscosity: If the viscosity exceeds 50cSt, use a high viscosity solenoid valve.

2.3 Pressure Parameters

1) Nominal pressure;
2) Working pressure: if the working pressure is low, use direct-acting or step-by-step direct-acting type; when the minimum working pressure difference is above 0.04Mpa, use direct-acting, step-by-step direct-acting, and pilot-operated type.

2.4 Voltage Selection

AC220V and DC24 are preferred.

2.5 Operating Duration

1) When the solenoid valve needs to be opened for a long time, and the operating duration is longer than the closing time, the normally open type should be selected;

Figure 3: 2-Way Normally Open Solenoid Valve.

2) If the opening time is short, select the normally closed type;
3) For working conditions that require safety protection, such as furnace and kiln flame monitoring, use the long-term power-on type instead of the normally open type.

2.6 Other Functions

Other functions include explosion-proof, non-return, manual, waterproof, etc., which can be selected according to the environment.

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