Complete Guide to Check Valve Selection and Installation: Detailed Explanation of Principles, Selection, and Key Construction Points Check valves, as crucial safety components in pipeline systems, are essential for preventing medium backflow and ensuring safe system operation. This article will provide you with a comprehensive guide to the selection and installation of check valves.

1. Operating Principle and Classification of Check Valves 1.1 What is a Check Valve?

Check valves, also known as one-way valves or non-return valves, belong to the category of automatic valves. Their working principle is to achieve opening and closing through the flow force of the medium itself. Their core function is to prevent the reverse flow of pipeline medium and ensure one-way flow.

1.2 Main application scenario: foot valve (a special type of check valve) at the water pump suction inlet

Various pipeline systems requiring unidirectional flow of medium

Industrial settings where accidents caused by medium backflow are to be prevented

II. Selection Criteria and Guidelines for Check Valves 2.1 Basic Selection Principles Medium Adaptability: Suitable for clean medium conditions, not recommended for pipelines containing solid particles or high viscosity media.

2.2 Selection of pipeline size (DN) based on pipeline size. Recommended valve types. Applicable pressure range: DN<50mm. Butterfly check valve, vertical lift check valve, diaphragm check valve. Low-pressure environment: 50mm

Advantages: Effectively eliminates the water hammer phenomenon

Limitations: Subject to temperature and pressure constraints, suitable for low-pressure and normal-temperature pipelines

Applicable scenario: Water supply pipelines prone to water hammer

Slow-closing check valve:

Slow-closing swing check valve

Slow-closing butterfly check valve

Applicable scenario: pipeline systems that require minimal or no water hammer impact when shut down

III. Installation specifications and construction requirements for check valves 3.1 Preparatory work before installation Appearance inspection:

Check the valve nameplate information to ensure compliance with the GB 12220 "General Valve Marking" standard

Check the integrity of the valve and confirm that it is undamaged

Pressure test requirements:

If the working pressure exceeds 1.0 MPa or the main pipe shut-off valve is involved, a pressure test must be conducted

Strength test: Nominal pressure × 1.5, duration ≥ 5 minutes, no leakage is considered as qualified

Tightness test: nominal pressure × 1.1, determine the duration according to GB 50243 standard

3.2 Installation location and direction: Strictly follow the design drawings to determine the location, height, and inlet and outlet directions

Flow direction indicator: Ensure that the flow direction of the medium is completely consistent with the direction indicated by the arrow on the valve body

Pipe support:

It is prohibited to let the check valve bear the weight of the pipeline

Large check valves must be equipped with independent support structures

Avoid direct impact of piping pressure on the valve

3.3 Lift check valves are required for specific types of installations:

Vertical flap type: It must be installed on a vertical pipeline

Horizontal flap type: It must be installed on a horizontal pipeline

Swing check valve:

Ensure that the valve disc's rotating shaft is in a horizontal position during installation

Special attention should be paid to the flow direction of the medium during inclined installation

IV. Common Installation Errors and Precautions 4.1 Example of Incorrect Installation: Installing a Vertical Lift Check Valve on a Horizontal Pipe

The valve flow direction is reversed

Large valves have no independent support

Pressure testing was not conducted according to specifications

4.2 The selection and installation location of check valves should be considered during the design phase of the professional advice system

Provide complete operating condition parameters to the supplier during procurement to obtain professional selection advice

For complex systems, it is recommended to consult a professional valve engineer

Conduct regular maintenance and inspection to ensure the check valve operates in normal condition

5. Maintenance points: Regularly check whether the valve can be opened and closed flexibly

Monitor for abnormal sounds, such as water hammer impact

Check the sealing performance to prevent internal leakage

Lubricate the moving parts to ensure normal operation

The correct selection and installation of check valves are crucial for ensuring the safe operation of pipeline systems. Following the selection guidelines and installation specifications provided in this article can prevent various accidents caused by medium backflow, extend the service life of valves, and reduce maintenance costs.

In practical applications, it is recommended to consider specific engineering requirements and medium characteristics, and if necessary, consult professional valve technicians to ensure the optimization of the selection and installation plan.