Model 990.FD

Clamped Diaphragm Seal Between Upper and Lower Housing, Flanged Connection

Threaded Design

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  • Suitable for corrosive, contaminated, highly viscous or hot pressure media
  • Chemical process industry
  • Petrochemical industry
  • High process pressures

Special Features

  • Flanged process connection per EN/ASME (NPS) ½", ¾", 1" or DN 15, 20, 25
  • Design with internal diaphragm and diaphragm bed, upper and lower housing threaded
  • Wide variety of special materials


Pressure rating
PN 25 ... 40 resp. class 150 ... 600

Suitable pressure ranges
0 ... 15 psi to 0 ... 1000 psi

Upper housing (instrument connection)
Material stainless steel 316 L, ½ NPT

Material stainless steel 316 L, welded with upper housing
Effective diameter of diaphragm Mb = 2.1"

Sealing ring
FPM (Viton®) max. 392 °F

Lower housing (process connection)
Material stainless steel 316 L
NPS 1", 1½" per ASME B 16.5, RF 125 ... 250 AA

Fastening parts
Retainer flange, hexagonal bolts and nuts:
galvanised steel max. 392 °F

Optional extras

Upper housing (instrument connection)

  • Carbon steel plated
  • Cooling tower for directly mounted gauge when fluid temperature > 392 °F


  • Stainless steel 316TI, 316, 904L, 321
  • Hastelloy B3, C276, Monel 400, Nickel, lnconel 600,
  • lncoloy 825, tantalum, titanium
  • PTFE coated
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