Pressure Measurement

High Purity Pressure Transducer – GCT 225


Setra’s Model GCT-225 Series is idealfor pressure measurement applications that require exceptional insensitivity to environmental extremes. The GCT-225 is insensitive to factors such as torque effect on the fitting, temperature transients, and RFI effects generated by other instruments and equipment.

Designed with a low cavity volume of 0.11 in3, the GCT-225 can be easily purged. All wetted parts are high quality VAR 316L SS, electropolished to 7 Ra (10 max.) finish, and every sensor is mass spectrometer helium leak tested to 1 x 10-9 ATM.CC/sec.

In a typical Setra configuration, a compact housing contains two closely-spaced, parallel, electrically-isolated metallic surfaces, one of which is essentially a diaphragm capable of slight flexing under applied pressure. The diaphragm is constructed of low-hysteresis material such as 17-4 PH SS or a proprietary compound of fused glass and ceramic (Setraceramâ„¢). These firmly secured surfaces (or plates) are mounted so that a slight mechanical flexing of the assembly, caused by a minute change in applied pressure, alters the gap between them (creating, in effect, a variable capacitor). The resulting change in capacitance is detected by a sensitive linear comparator circuit (employing proprietary, custom-designed ASICs), which amplifies and outputs a proportional, high-level signal.

  • Superior stability avoids downtime
  • EMI/RFI immunity prevents false shutdown
  • Sturdy design allows trouble-free installation
  • Meets CE conformance standards
  • Gas Cabinets
  • High Purity Gas Delivery Systems
  • Semiconductor Process Tools

Technical Details

Accuracy* RSS (At Constant Temp.)±0.25% FS
Non-Linearity, BFSL±0.15% FS
Hysteresis0.20% FS
Non-Repeatability0.02% FS
Thermal Effects**
Compensated Range °F(°C)0 to +150 (-18 to +65)
Zero/Span Shift %FS/°F(°C)0.033 (0.06)
Maximum Line Pressure2.0 (1.8)
OverpressureMass Spectrometer Helium Leak
Tested to 1 x 10-9 ATM CC/Sec.
* RSS of Non-Linearity, Non-Repeatability and Hysteresis.
**Units calibrated at nominal 70°F. Maximum thermal error computed from this datum.

Physical Description

CaseStainless Steel
Electrical Connection6ft./1.8m Multiconductor
Cable or 4-Pin Bayonet Connector
Pressure Fitting#4 Face Seal Swivel Male or Female, 1/4″ NPT Male, or Tube Stub
VentThrough Cover
Internal Cavity Volume0.11 in.3
Wetted MaterialVAR 316L SS Electropolished to
7 RA (10 max.) Finish
Weight (Approximate)4 ounces (113 grams)

Environmental Data

Operating* °F (°C)-40 to +185 (-40 to +85)
Storage °F (°C)-40 to +185 (-40 to +85)
*Operating temperature limits of the electronics only.
Pressure media temperatures may be considerably higher or lower.

Note: Specification are subject to change without notice