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GP140 Series Diaphram Seal

Process Pressure Gauge Chemical Seals & Isolators

The GP140 Series includes 3D Instruments’ rugged line of gauge protectors and diaphragm seals. All seals are precision micro-matched at our facility for accuracy and reliability. Because our Direct Drive bourdon element has a fluid path volume of only 2 cc or less, it has a 20 times smaller volume than standard C-type. The resultant displacement of  0.08 cc or less allows 3D to offer unmatched gauge protection while maintaining accuracy and sensitivity better than any other diaphragm pressure gauge seal available.

GP140 Series Metallic Diaphragm


  • Welded body constructed of 316 stainless steel or Hastelloy C (other materials available)
  • Metallic diaphragm manufactured from 316L stainless steel or Hastelloy C (other materials available)
  • Available in 1/4” or 1/2” process connections
  • Available with process flush port
  • More compact design than industry standard diaphragm pressure gauge seals (1-1/2” hex, max)
  • Low effects on accuracy: 0.05% on a 30 PSI Gauge, 0.02% on a 60 PSI Gauge. No accuracy adders on ranges from 100 PSI to 2000 PSI. )
  • Low temperature effects: 0.2% per 10°F on a 100 PSI gauge; 0.003% per 10°F on a 1000 PSI gauge for models KT & KET


  • Highly corrosive chemical environments
  • Highly viscous processes
  • Processes prone to plugging or fouling
  • Very high pressure pulsations
  • Service pressures of 30 to 2000 PSI
  • Ranges below 100 PSI have a small accuracy effect.
316 SS upper & lower KT
316 SS upper Hastelloy C lower & diaphragm KET
1/4 inch NPT process connection B
1/2 inch NPT process connection C
1/4 inch NPT process connection B
1/2 inch NPT process connection C

Diaphragm Pressure Gauge Isolators Specification Guide

1.     Model Number: Used with gauge

2.     Welded diaphragm or removable diaphragm

3.     Process or inlet connection size

a.     Threaded type: 1/4” NPT, 1/2” NPT, 1” NPT, other

b.    Flanged type: Pipe size, pipe schedule, ASA pressure rating, flange facing

4.     Instrument or outlet connection size: 1/4” NPT, 1/2” NPT

5.     Material of wetted parts:

a.     Lower Housings 316 SSTL, Hastelloy-C, Monel or other Alloys available

b.    Diaphragm 316 SSTL, Hastelloy-C, Monel, Tantalum or other Alloys available

c.     O rings Viton, Teflon or other elastomers available

6.     Material of upper housing 316 SSTL, Carbon Steel or other Alloys available

7.     Fill liquid: Glycerin, silicone, mineral oil, Fluorolube, other

8.     Approximate media operating temperature

9.     Maximum media operating temperature

10.  Approximate operating pressure

11.  Maximum pressure

12.  Media material

13.  Material used in media piping or housing

Optional Features:

  • Flushing connection
  • Connecting line (316 stainless steel capillary)
  • Clean-out capability without disturbing fill
Related Files:
GP-140 Chemical Seal DataSheet
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