Setra System Model 204D - Manual (Page 2)

Installation of Pressure Fittings
Your transducer is designed for most accurate operation when subjected to pressures
within the designated pressure range. Refer to the catalog bulletin specifications for
proof pressure limits. Subjection to excessive pressure voids the warranty. DO NOT
OVERPRESSURE.
Standard sealants such as Teflon pipe tape generally are satisfactory. For the most
sensitive pressure ranges, excessive high torquing of a metal pressure fitting may cause
slight zero shift which may be trimmed out using the zero adjustment. Use of a plastic
fitting often shows no noticeable zero shift. The torquing effect does not appreciably
affect linearity or sensitivity. The wrench flat on the 204 and 239 series should be used
when installing the positive pressure fitting.
A. Positive Pressure Fitting and Media Compatibility
Model 204, C204, 204D: 1/4”-18 NPT internal fitting
For use with gases or liquids compatible with 17-4 PH
stainless steel. (316 stainless steel optional)
Model 239, C239: 1/8”-27 NPT internal fitting
For use with gases compatible with stainless steel, hard
anodized 6061 aluminum, Buna N “O” ring. (stainless steel
in place of aluminum optional)
B. Reference Pressure Fitting and Media Compatibility (Differential pressure measure-
ments only.)
Model 204D: 1/8”-27 NPT internal fitting
For use with clean dry air, non- corrosive or non-conduc-
tive gases.
Maximum line pressure 1000 psig.
Model 239, C239: 1/8”-27 NPT internal fitting
For use with non-corrosive, non-condensing clean dry air
or other gases. Maximum line pressure 250 psig.
Notes:
(1) Differential pressure Models can be used to measure gauge pressure by leav-
ing the reference port open to atmosphere.
(2) Line Pressure refers to pressure applied to both high and low sides of the
sensing device simultaneously. Refer to the product data sheet to determine
maximum differential pressure and overpressure limits.
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High
Low
204D, 239, C239
Installation Instructions for Multiple Hook-Up of
4-Wire Pressure Transducers (24 VDC Units Only)
PS - Power Supply (nominal 24 VDC)
PT - Pressure Transducer (4-Wire Circuit)
DVM/DAS - Digital Voltmeter or Data Acquisition System
Option #1
Uses a single, ground referenced power supply for excitation and separate, isolated differential input
(not ground referenced) readout or data acquisition system for each pressure transducer output.
Option #2
Uses a separate, isolated power supply for each pressure transducer’s excitation and a single, ground
reference (single ended input) readout or data acquisition system for all of the outputs.
Option #3
Uses a single, ground referenced power supply for excitation and either a single, isolated readout
with a bipolar switch that “breaks before makes” both the + output and the - output of each pressure
transducer, or a single data acquisition system with a multiplexer (MUX).
Note: The shield is internally commoned to the case and pressure port of the transducer. When the shield is connected to
ground, the case and pressure port of the transducer will also be commoned to that ground.
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