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TUFF GUARD Gauge Isolators
PTFE Diaphragm, 1/4" Female NPT Inlet Connection
Protects and Isolates Pressure Sensing Instruments

  • Impermeable PTFE Diaphragm, Convoluted for Accurate Pressure Transmission.
  • Stainless steel reinforced instrument connection. Integrally molded. "Unbreakable!"
  • Reinforced process connection with compressive spoke ribs to transfer the tensile stress into compression.
  • Wall thickness meet or exceed ANSI Schedule 120.
  • Sufficient displacement to handle the required volumetric displacement of all instrument sizes and pressure ranges.
  • Self Venting Internal Shape for "Easy Filling"
  • Fill/Bleed port provision, reinforced through upper chamber to allow for threaded connections in vacuum fill processing.
  • Integral wrench provisions for field service and maintenance. Diaphragm is Replaceable.
  • Low Profile Design eliminates Dead Volume
  • 3 year limited warranty
Unit of Measure


Inlet Connection

N/A 1/4" Female NPT


N/A PVC, PTFE Diaphragm

Installed Gauge

N/A 0-60 PSI, All Stainless



  • The Marquest Gauge Isolator provides two fluid chambers separated by an impermeable membrane. The upper chamber (instrument side) is normally filled with a stabilized liquid. The lower chamber receives the media under pressure.
  • Most pressure sensing devices are compatible with 1/4" FNPT outlet. The inlet is standard 1/2" FNPT or 1/4" FNPT.
  • Chemical resistance and purity levels are as recommended for the base materials.
  • No lubricants are used in construction, internally or externally.
  • Custom membranes may be supplied upon request.

Materials of Construction

N/A Body:

  • PVC: Polyvinyl Chloride
  • CPVC: Chlorinated Polyvinyl Chloride
  • PP: Polypropylene homopolymer, glass & mineral reinforced
  • Standard: PTFE®, also available in:
  • FPM: Viton®, Fluorine elastomer
  • EPDM: Ethylene Propylene elastomer



  • Protects and isolates pressure sensing instruments
  • Total isolation from system media
  • Low profile design eliminates dead volume
  • Convoluted diaphragm allows accurate transmission of system pressure
  • Optimum pressure containment spherical design
  • Low in original cost and maintenance
  • Simple installation

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