How To Select Ideal Check Valves for Specific Applications

I. Understanding the Basic Types of Check Valves

Swing Check Valve:

Its disc rotates around a pin shaft. The advantages of this type of check valve lie in its relatively simple structure and low flow resistance, making it suitable for large-diameter pipelines and occasions with high flow requirements. For example, in some large-scale water supply systems or heating pipelines, when the medium flows forward, the disc can be easily opened to ensure the smooth transmission of water flow or heat medium; once backflow occurs, the disc will quickly close under the action of gravity and the reverse force of the medium to prevent backflow.

Lift Check Valve:

It can be installed in horizontal and vertical forms. It relies on the disc moving up and down along the passage of the valve body to achieve the function of preventing backflow. This type of check valve has good sealing performance and is more suitable for systems with strict requirements on medium leakage. For example, when transporting some toxic, harmful, flammable, and explosive liquid media in chemical production, it can effectively prevent the reverse leakage of the medium and ensure safe production.

Butterfly Check Valve:

Its appearance is similar to that of a butterfly valve, and it controls the flow direction of the medium by rotating the disc-shaped disc. It features a compact structure, light weight, and small installation space requirements, and is widely used in some pipeline systems with limited space. For example, it is very suitable for installing butterfly check valves in the water supply and drainage pipelines inside buildings, especially in some relatively narrow pipe shafts. Moreover, it is sensitive in operation and can quickly respond to changes in the flow direction of the medium.

Diaphragm Check Valve:

It uses an elastic diaphragm to control the flow of the medium. The diaphragm will deform with the forward or reverse flow of the medium to achieve opening and closing. This type of check valve performs excellently in some occasions with high requirements on medium cleanliness and where it is not desired that metal parts have excessive contact with the medium, such as the pipeline transportation systems in the food and beverage industry, which can avoid contaminating the products.

II. Considering the Characteristics of the Medium

1. Medium Type
   If it is used to transport common, relatively clean, and less corrosive media like water, multiple types of check valves can be applicable. However, other factors such as flow rate and pressure need to be comprehensively considered for further screening. But if it is to transport corrosive chemical liquids, such as strong acids like hydrochloric acid and sulfuric acid, check valves made of materials with strong corrosion resistance need to be selected, for example, check valves made of materials such as stainless steel and plastics (such as polytetrafluoroethylene, etc.), to ensure the service life of the valve and the safe and stable operation of the system. For transporting slurry media containing solid particles, such as the slurry transportation pipelines in mine beneficiation, check valves with relatively spacious flow channels and that are not easily blocked by particles should be chosen, and swing check valves often have more advantages in such cases.
2. Medium Temperature
   Different check valve materials can withstand different temperature ranges. In a low-temperature environment, for example, in the refrigerant pipelines of some refrigeration systems, it is necessary to ensure that the materials of the check valve will not become brittle due to low temperature and affect performance. It may be necessary to select valves made of special materials such as low-temperature alloy steel. In a high-temperature environment, for example, in the steam transportation pipelines of thermal power plants, the temperature is often as high as several hundred degrees Celsius. This requires that the materials of the check valve have good high-temperature strength and thermal stability. Check valves made of materials such as chromium-molybdenum alloy steel can meet the usage requirements and prevent problems such as valve deformation and seal failure caused by high temperature.

III. Focusing on the Pressure Parameters of the Pipeline System

1. Working Pressure: The check valve must be able to withstand the working pressure during the normal operation of the pipeline system and a certain safety margin should be reserved. For example, in a high-pressure water supply system, the working pressure may reach several megapascals. In this case, it is necessary to select a check valve with a pressure rating matching it. Generally speaking, a product with a pressure rating slightly higher than the actual working pressure according to relevant standards should be selected to cope with possible pressure fluctuations and other situations, ensuring that the check valve will not be damaged or leak due to excessive pressure during long-term operation.

2. Pressure Fluctuation Situation: In some pipeline systems, pressure will fluctuate frequently. For example, in the pipelines of some industrial production devices that operate intermittently, the start and stop of equipment will cause instantaneous changes in pressure. In view of this situation, check valves with high structural strength and the ability to adapt to pressure impacts should be selected, such as those with buffer devices or with a more stable disc design. During pressure fluctuations, they can better maintain the sealing performance and avoid faults such as abnormal opening or poor closing of the disc caused by instantaneous pressure changes.

IV. Analysis of Flow Requirements

1. Flow Rate: For pipeline systems with large flow rates, such as the main water supply pipelines in cities or large irrigation system pipelines, check valves with low flow resistance need to be selected. Swing check valves are usually a better choice. They can ensure a large flow rate while not causing excessive pressure loss and ensure the water supply efficiency and pressure stability of the entire system. For pipelines with relatively small flow rates, such as the water supply and drainage pipelines inside households, small check valves like butterfly check valves that can meet the flow requirements are sufficient for the job.

2. Flow Stability Requirement: In some process pipelines with high requirements for flow accuracy, such as the liquid transportation pipelines for precise batching in pharmaceutical production, it is necessary to ensure that the check valve will not cause significant interference to the flow during normal operation, and that the flow will not have obvious fluctuations caused by the valve action while preventing backflow. At this time, check valves that are sensitive in operation and have little impact on the flow need to be selected, such as some new check valve products with advanced sealing and valve core designs, which can better meet such flow stability requirements.

V. Limitations of Installation Space and Environmental Conditions

1. Installation Space: If the installation space of the pipeline system is relatively narrow, such as in the engine rooms of ships or the narrow pipe shafts of buildings, check valves with small external dimensions and compact structures need to be selected. Butterfly check valves, miniature lift check valves, etc. are more in line with the requirements. They can be smoothly installed in the limited space and achieve normal functions. For the pipelines outside large industrial plants where the space is relatively abundant, the limitations on the external dimensions of check valves are relatively small, and appropriate check valve types can be preferentially selected according to other performance factors.

2. Environmental Conditions: When installing check valves outdoors, the impact of the environment needs to be considered, such as whether they will be exposed to wind, rain, sunlight, etc. Check valves with good protective coatings and corrosion resistance need to be selected to prevent damage caused by long-term exposure to harsh environments. If it is in an area with explosion hazards, such as some flammable and explosive environments in petrochemical production, check valves with explosion-proof performance need to be selected to ensure the safety of the entire system.