Technical Analysis and Application Guide for Control Valve Diaphragms

一、Core Functions and Types

1. Functional Role

   • As the core component of pneumatic/hydraulic control valves, the diaphragm converts control signals (air pressure/hydraulic pressure) into mechanical displacement, driving the valve plug to move and achieve precise regulation of parameters such as flow rate and pressure.

   • Key Indicators: Pressure resistance (typically 0.2–1.6 MPa), displacement stroke (5–50 mm), service life (≥1 million cycles).

   
   

2. Common Types

   Type	Materials	Applicable Scenarios
   Rubber diaphragm	NBR, EPDM, Fluorocarbon Rubber	Water treatment, chemical processing (corrosion-resistant media)
   Metal diaphragm	Stainless steel, Hastelloy	High-temperature and high-pressure environments (e.g., steam systems, nuclear power)
   Composite Diaphragm	PTFE + Fiber Reinforced Layer	Strong acids and strong alkalis, high-purity media (semiconductors)

   
   

二、Selection and Design Considerations

1. Material Selection

   • Chemical Compatibility: Materials must be selected based on their properties (e.g., EPDM for acid and alkali resistance, PTFE for solvent resistance).

   • Temperature Range:   NBR (-30°C to 80°C), Fluorocarbon rubber (-20°C to 200°C), Metal diaphragm up to 600°C.

   
   

2. Structural Optimization

   • Corrugated Design: Increase flexibility and travel (e.g., multi-layer corrugated structures enhance sensitivity).

   • Edge reinforcement: Metal ring embedded to prevent tearing (commonly used in high-pressure applications).

Model Selection Recommendations