400-401 All-Welded Diaphragm Seals

The Ashcroft® 400 and 401 all-welded diaphragm seals protect pressure measuring instruments. Used to ensure process compatibility, they are also applied when process media exhibit high temperature, pulsation or the potential to clog an instrument connection. An ideal selection for applications requiring minimal potential leak paths.

Key Features:
  • Select diaphragm and lower housing materials
  • All-welded construction
  • Carbon steel rings (standard); 300 stainless steel rings (optional)
  • Pressure rated up to 4,400 psi; optional high-pressure rings to 9,000 psi (type 401: 5,000 psi )
  • Flush port (type 401) provides easy cleaning / flushing for process media prone to clogging

Process Market:
Oil and Gas
Chemical and Petrochemical
Water and Wastewater

Process Applications:
Oil and Gas Fracking
NACE Compliant Processes (Sour Gas Separation)
Biogas and Biodiesel


Certifications & Approvals

Data Sheets & Instruction Manuals

Drawings & Product/Technical Information

Resources & Tools

Min/Max Guide

IMPORTANT! When selecting a diaphragm seal or isolation ring, refer to the Min/Max Guide (PI page) for compatibility with this gauge. 

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Materials Selector

Use the selector to review compatible wetted materials and requirements of your application.

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Unit Converter

Need to convert measurement units? Check out our quick and easy tool to convert pressure, temperature and flow units of measure.

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Product Information

To learn more about the technical details for options available, review our product information (PI) pages.

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