How to Select the Right Strainer for Your System

Strainers are small devices used to remove solid particles from liquids or gases in pipeline systems. They are widely utilized across various industrial applications to protect downstream equipment and ensure the purity of the fluid. By efficiently screening out contaminants, strainers prevent equipment damage and improve system efficiency and safety. This guide explains the basic working principles of strainers, their types, key selection factors, and their importance in different applications.

Strainer Classifications

Strainers can be categorized based on their structure, application, and filtration precision. Below are some common types.

1. Y-Pattern Strainer

Features: The Y-pattern strainer features a compact design with a Y-shaped body, offering a short fluid flow path. It is suitable for pipelines with smaller diameters and lower flow rates.

Applications: Y-pattern strainers are commonly used in liquid or gas filtration systems, such as water treatment systems, compressed air systems, and steam pipelines.

Advantages: These strainers are easy to install, save space, and are ideal for filtering low-viscosity media.

2. Basket Strainer

Features: Basket strainers are equipped with a large filtration area, making them suitable for filtering fluids with higher levels of impurities or high viscosity.

Applications: Basket strainers are commonly used in industries like petroleum, chemicals, and food processing, where fluid flow is large, and the level of contaminants is high.

Advantages: These strainers offer high filtration capacity and cleaning efficiency, making them ideal for large-flow, long-running pipeline systems.

3. T-Pattern Strainer

Features: T-pattern strainers are installed in horizontal pipelines, providing high filtration precision and low pressure loss.

Applications: These strainers are ideal for applications requiring high filtration accuracy, such as gas pipeline systems.

Advantages: Their simple design allows for precise filtration with minimal pressure loss.

Key Factors for Strainer Selection

When selecting a strainer, it is essential to consider the specific requirements of the application. Below are the key factors to consider.

1. Inlet and Outlet Diameter

The strainer's inlet and outlet diameters should match the pipeline diameter to ensure smooth fluid flow without obstruction. Generally, the strainer's inlet and outlet sizes should align with the pump's inlet size. For example, if the pipeline diameter is DN100, the strainer should also be DN100.

2. Pressure Rating

The strainer's pressure rating should match the pipeline system's maximum working pressure. If the system operates at PN25 pressure, choose a PN25-rated strainer to ensure safe and stable operation under high-pressure conditions.

3. Mesh Size

The mesh size determines the filtration precision. The higher the mesh number, the finer the particles it can capture. Mesh size should be chosen based on the medium and required filtration precision:

Water: Mesh sizes between 40 and 80 are commonly used.

Steam: Mesh sizes between 100 and 200 are typical.

Gas: Mesh size depends on the required gas purity. Mesh size refers to the number of holes per inch in the mesh; higher mesh numbers indicate smaller holes and finer filtration.

4. Material Selection

The strainer's material should match the material of the connected pipeline. Common materials for strainers include:

Carbon Steel: Suitable for non-corrosive media.

Stainless Steel: Ideal for corrosive media, resisting most acids and alkalis.

Fluoropolymer or Rubber Lining: Used for filtering highly corrosive media or in extreme conditions. Selecting the right material is crucial for ensuring the strainer's longevity and safe operation, especially under high temperature, high pressure, or low temperature conditions.

5. Pressure Loss

Strainers create some fluid resistance. When selecting a strainer, ensure that its pressure loss at the rated flow rate is reasonable. For water strainers, typical pressure loss is between 0.52 and 1.2 kPa. By choosing the appropriate mesh material and design, energy loss in the system can be minimized.

6. Connection Type

Strainers can be connected using either socket weld connections or flange connections:

Socket Weld Connection: Suitable for small-diameter pipelines or applications with limited space.

Flange Connection: Ideal for large-diameter pipelines, especially when frequent maintenance or replacement is required.

Strainer Applications

Strainers are used in a wide range of industries, with applications tailored to the specific needs of the medium and process. Below are common strainer applications.

1. Water Treatment Systems

Strainers in water treatment systems remove suspended solids, sediment, and rust from water. Y-pattern and basket strainers are commonly used, with mesh sizes typically between 40 and 80 to ensure the water meets the required standards.

2. Steam Pipelines

In steam pipelines, strainers remove water droplets and impurities from steam to prevent corrosion and scaling. The typical mesh size for these strainers ranges from 100 to 200 to meet high-temperature and high-pressure filtration requirements.

3. Oil and Gas Industry

In the oil and gas industry, strainers remove solid contaminants from fluids to protect pumps, compressors, and other equipment. Basket strainers, with their large filtration area and high contaminant resistance, are commonly used in these applications.

4. Chemical Processes

In the chemical industry, strainers are used to filter corrosive media. Material selection is especially important in these applications, with stainless steel, fluoropolymer, and rubber-lined strainers providing excellent corrosion resistance.

5. High Viscosity Media Filtration

For high-viscosity fluids, basket strainers or automatic cleaning strainers are more suitable. These strainers can effectively handle high-viscosity and high-impurity fluids, ensuring stable system operation for an extended period.

Conclusion

Choosing the right strainer is critical to ensuring the proper functioning of a pipeline system. A correct choice prevents equipment damage from impurities, improves process efficiency, and reduces maintenance costs. By considering factors such as pipeline diameter, flow rate, pressure rating, mesh size, material, and connection type, users can ensure long-term stable operation and enhance the overall reliability and safety of the system.