Check Valve and Non-Return Valve Procurement & Selection Guide: How to Accurately Describe Application and Operating Conditions

Technical Concepts and Application Differences Between Check Valves and Non-Return Valves

In industrial fluid control, "check valve" and "non-return valve" are often used interchangeably to refer to valves that allow fluid to flow in a single direction and prevent backflow. However, in engineering and procurement communication, their focus differs. Generally, "check valves" are widely used in hydraulic and pneumatic systems, emphasizing high-pressure resistance, precise response, and specific cracking pressure control. Conversely, "non-return valves" are commonly used in piping systems like industrial water supply, drainage, and petrochemicals, serving medium-to-low pressure, large-diameter backflow protection. When selecting a valve, providing just the name is insufficient; procurement personnel must combine specific media and operating conditions to clearly describe the actual application in the system.

Core Technical Parameters Required for Procurement and Selection

To ensure the selected valve meets field operating requirements, procurement personnel should provide complete environmental and operating condition parameters during inquiries. First is the working medium, such as hydraulic oil, water, steam, or corrosive liquids. The viscosity and temperature of the medium directly determine the choice of valve body material (e.g., carbon steel, stainless steel) and seals (e.g., NBR, FKM, metal-to-metal hard seal). Second are working pressure and flow rate requirements, including the maximum system working pressure and the cracking pressure of the check valve. An excessively high cracking pressure may increase system energy loss, while an overly low cracking pressure may affect seal performance. Additionally, pipe connection methods are crucial technical details in selection.

• Working medium type and temperature range (e.g., anti-wear hydraulic oil, ambient water, etc.)
• Maximum system working pressure and cracking pressure requirements
• Nominal pipe size (DN) or port thread/manifold mounting specifications
• Rated medium flow rate and maximum allowable pressure drop
• Preferences for valve body material and seal material
• Installation position and space constraints (horizontal or vertical installation)

Key Points of Functional Description in Typical Application Scenarios

Describing the actual use in conjunction with specific system functions can significantly improve communication efficiency with suppliers. For example, if the valve is used at a hydraulic pump outlet to prevent system pressure backshock from damaging the pump, focus on specifying the pump's working pressure and response speed requirements. If used to prevent pipeline water hammer, specify the pipeline flow velocity and whether slow-closing features are required. If used in a bypass circuit as a safety relief or oil replenishment line, clearly specify the cracking pressure setting range. For hydraulic circuits with pressure-holding functions, clarify whether a pilot-operated check valve is needed. All specific parameters and special function requirements must be confirmed with the supplier during the actual inquiry.

Maintenance Inspection and Inquiry Preparation

Common issues with check valves and non-return valves during daily operation include spool jamming, internal leakage caused by seal failure, and poor opening performance. During routine inspection and maintenance, observe whether there are leakage marks on the exterior of the valve body and listen for abnormal noises or severe vibrations during operation. If poor non-return performance or abnormal system pressure drops occur, check if media cleanliness meets specifications, as particulate impurities are a primary cause of sealing surface damage. For repairs involving high-pressure hydraulic systems or hazardous medium pipelines, safety regulations must be strictly observed by relieving system pressure and disconnecting power first. When dealing with complex faults or internal component replacements, contact the supplier or technical professionals for assistance. Preparing accurate field operating conditions and functional descriptions when organizing inquiry materials can effectively shorten communication cycles and improve selection accuracy.