Diaphragm seal is known for vital component for process control devices serving as protective isolating structure for sensing elements of gauges, sensors and transmitters against harsh process conditions—corrosive chemicals, viscous fluids, or extreme temperatures, etc. The choice of diaphragm structure hinges on working environment and requested functionalities of the measuring device and there are also multiple mounting methods of diaphragm connection for site-specific requirements.
According to distance between instrument body to process tapping point, its installation approaches can be classified as direct installation and remote installation:
Direct Installation: The simple way of connecting the diaphragm directly on the process who is attached with main instrument body and formed an integrated unit. The straightforward connection is suitable for moderate and stable environment. The sensing element operates closely to the process and ensures fast response time and sensitivity on trivial fluctuation of process variable. Industries like water treatment or general manufacturing often favor this cost-effective approach simplifying structural design. However, the method is unsuitable for extreme temperature or strong vibration, as main instrument body remains in the proximity of harsh ambient conditions.
Remote Installation: Remote setup is advantageous when the instrument has to be placed away from harsh process conditions it cannot withstand—extreme temperature, hazardous atmosphere or mechanical vibration. In the case diaphragm seal is decoupled from body utilizing flexible capillary. Fill fluid inside capillary can transmit pressure forced on diaphragm to the sensor positioned in a distance. Length of capillary and selection of fill fluid base on temperature compatibility and process layout. Capillary remote mounting enhances reliable performance and device safety in more challenging environment, hazardous and high-temperature sectors among fields such as oil & gas and chemical processing often prefer remote mounting for process control
As per connecting fitting, diaphragm seal mounting have three general connections:
Thread connection: Small diameter flat diaphragm is suitable for straightforward threaded mounting (G, NPT, Metric, etc.). It is widely compatible and cost-effective among general low-to-medium pressure applications and allows easy installation in tight spaces. However thread connection may not withstand high vibration or heat without additional support.
Flange connection: Flange attaches the diaphragm seal to a flange and secures high level of tightness connection with process pipeline or vessel, common in high-pressure or large-diameter systems. The seal integrates with standardized flanges (ANSI, ASME, JIS or GB/T, etc.), often using bolted connections for robustness. Weld-neck, slip-on, or threaded flanges are selected based on pressure ratings and installation condition.Flange ensures leak-tight performance in demanding conditions and it should be aware that proper flange alignment and placement of gasket are critical to leak prevention.
Clamp connection: In food, pharmaceutical, and biotechnology sectors, sanitary mounting ensures compliance with strict hygiene requirements. Diaphragm seals using tri-clamp hygienic fittings are designed for easy cleaning and sterilization. Smooth, crevice-free surfaces prevent bacterial growth, while materials like 316L stainless steel resist corrosion. While featuring quick installation and excellent contamination control, it should be noticed that clamp may not be suitable for high pressure applications.
Each mounting method of diaphragm seal can offer unique benefits tailored to specific industrial needs. By carefully evaluating process requirements and environmental factors, engineers can optimize installation for reliability, safety, and cost-efficiency. Proper selection and installation not only extend product useful life but also ensure reliable process control across diverse applications. Shanghai Wangyuan is an experienced instrumentation manufacturer having considerable expertise in the use of diaphragm-sealed instruments. Should you have any questions or demands regarding our range of process solutions, please do not hesitate to get in touch.
Post time: May-09-2025