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300 Threaded Diaphragm Seal
The Ashcroft® 300 and 301 threaded diaphragm seals or isolation devices protect pressure measuring instruments.
Used when process compatibility is required, these are also applied when media exhibits high temperature or the potential to clog an instrument connection. Ideal for satisfying many challenging applications.
Ashcroft 300-301 Threaded Diaphragm Seals


Type 300: threaded; Type 301: threaded with flushing port
Process Size
NPT female: 1/4" to 1 1/2", NPT male: 1/4" to 1"
Pressure Rating
Rated up to 2,500 psi


  • 316L stainless steel top housing (standard)
  • Wide selection of diaphragm and lower housing materials
  • Diaphragm (elastomer) clamped between top and bottom housings
  • Flushing port (type 301) provides easy cleaning / flushing due to process media prone to clogging
Trust the Shield
Ashcroft's passion is to design, manufacture, and deliver the most innovative and well-crafted pressure and temperature instruments so you can always trust the shield.
Get more information on the 300-301 Diaphragm Seal from Ashcroft. 
Diaphragm Seal Assembly