Differential Pressure Transmitter Material Selection Criteria & Design

This article is about Differential Pressure Transmitter Material Selection Criteria & Design For Pressure Measurement of Instrumentation and Control Systems as per International Codes and standards for Commercial Buildings, Plants and Refinery Projects.

Differential Pressure Transmitter Material Selection Criteria & Design

Material Receiving General Checklist for Instrumentation & Control

General Requirements

Purchase Order and Instrument specification sheet criteria shall be confirmed and compared with instrument stainless steel tags / labels and nameplates, and shipment checked for damage, prior to acceptance of the shipment
Differential pressure transmitters shall be Smart. (Attachment 1)

Instruments and control systems shall operate continuously under the following ambient air temperatures without any degradation of the manufacturer’s guaranteed performance:

Verify that all the instruments are from technically acceptable vendors (Attachment 1).
All instrumentation purchases from manufactures that are not technically acceptable vendors, a request for technical evaluation, with justifications, shall be submitted in writing to the General Supervisor, Process Instrumentation Division, P&CSD.
The instruments should comply with the Saudi Aramco-defined standard conditions for process flow measurement:

Verify the field transmission signals are 3-15 PSI, 4-20 mA and vendor specific digital protocols when used between their controllers and their respective field devices.
If HART communication protocol is used, verify that the superimposed digital signal is not used for plant control.
All fieldbus devices should have FOUNDATION Field bus certification as having passed the latest revision of Interoperability Test Kit (ITK).
Verify that FF Devices and all function blocks shall be tested and certified by the host control system vendor.
Verify that FF Devices and all function blocks shall be downloadable into the devices by the end user.
All fieldbus devices should be capable of performing continuous diagnostics, including self-test functions, to provide specific diagnostic information at the Man Machine Interface (MMI).
All fieldbus instruments shall include menu’s and method’s (wizards) to allow easy set-up and calibration from the MMI.
Verify “certificate of compliance” for each type of nonincendive device, clearly showing the nonincendive field wiring parameters embedded, in viewable format, in the Fieldbus Segment Calculator (FFSC).
“As a minimum, all pressure devices shall be specified with over-range protection to 1-1/2 times the maximum system operating pressure.
[PIP PCCPR001 Sec 4.1.4, April 2007]”
Materials selection for pressure device wetted parts shall be type 304 or 316 stainless steel with TFE gaskets, unless other materials are required by process. [PIP PCCPR001 Sec 4.1.7, April 2007]
Standard ranges shall be selected such that the normal operating pressure falls between 30% and 70% of the scale range.
The requirements that apply to pressure measurement also apply to differential pressure measurement. [PIP PCCPR001 Sec.4.5.1, April 2007]
A differential pressure transmitter can be used to measure low gauge pressures by leaving one tap vented to atmosphere. The vented tap shall be protected from wind velocity changes. [PIP PCCPR001 Sec.4.5.2 & 4.5.2.1, April 2007]
A differential pressure transmitter can be used to measure low gauge pressures by leaving one tap vented to atmosphere. Screens shall be provided on the vented tap to protect from particle and insect intrusion.. [PIP PCCPR001 Sec 4.5.2 & 4.5.2.2, April 2007]

International Codes and Standards for Differential Pressure Transmitter

1. Flow Nozzle Material Selection Criteria Design & Flow Measurement
2. Venturi Tube Material Selection Criteria Design & Flow Measurement

3. SAES-J-002 – Technically acceptable instruments.
4. SAES-J-003 – Instrumentation Basic Design.
5. SAES-J-200 – Pressure.
6. SAES-J-904 – FOUNDATION fieldbus Systems.
7. PIP PCCPR001 – Pressure Measurement Criteria.

Attachment 1: Approved Vendor List of Differential Pressure Transmitter.