Ashcroft 402-403 Flanged All-Weld Diaphragm Seals

The Ashcroft® 402 and 403 flanged all-weld diaphragm seals or isolation devices protect pressure measuring instruments. Used to ensure process compatibility, they are also applied when process media exhibits high temperature, pulsation or the potential to clog an instrument connection. An ideal selection for applications needing added product integrity.

Key Features:

  • Wide selection of diaphragm and lower housing materials
  • All welded construction
  • Flushing port (type 103) provides easy cleaning / flushing due to process media prone to clogging


  • Style:
    Type 402: flange
    Type 403: flange with flushing port
  • Process size: 1/2" to 3"
  • Flange rating: 150 to 1500 class

The 402 and 403 flanged all-weld diaphragm seals are ideal where fugitive emission and hazardous process protection are essential:

Process Market:

  • Oil and Gas
  • Refineries
  • Chemical and Petrochemical
  • Water and Wastewater                                            

Process Applications:

  • Oil and Gas Fracking
  • NACE Compliant Processes (Sour Gas Separation)
  • Biogas and Biodiesel

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