standard specification for erection tender - GAIL

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specified area classification and weather proof to IP65/NEMA-4 and vendor shall
supply necessary isolating barriers between the transducers and
preamplifier/transmitter However the transducer/sensor housing can be flameproof
(EEx d) certified suitable for the specified area classification instead of intrinsically
safe.
6.10 Overall pressure drops across the meter assembly including meter runs shall
be less than 0.1 Kg/cm2g. Pressure drop calculation across the meter shall be
furnished.
6.12 Ultrasonic flow meter spool inside diameter to meet the specified I.D and
internal surface roughness shall be as per standard AGA Report no. 9.
7.0 METER ELECTRONICS AND SIGNAL PROCESSING
7.1 Meter assembly shall include a signal processing unit to perform all control of
the transducers and perform all calculations and statistical averaging for calculating
flow rate.
7.2 Extensive Diagnostic capability shall be provided to allow monitoring of
operating parameters of the meter, health of the transducers and signal quality etc.
These shall include parameters required to characterize the performance of the meter
and confirm its compliance to AGA-9. The diagnostic functions shall be supported by a
PC-based engineering/maintenance software tool.
7.3 Signal processing unit shall perform all flow computer functions, including
calculations to correct for pressure, temperature and compressibility to provide
corrected flow rates and flow totals at standard conditions. Compressibility
calculations shall be based on the latest version of AGA Report No.8 using the
detailed characterization method. Gas quality data, shall be input via the station PLC
or RTU from live GC data from the nearest online gas chromatograph.
7.4 The signal processing unit shall be equipped with a minimum of two serial
communication ports. One port shall be used for connection to the station PLC / RTU
or flow computer. The second port shall be used for maintenance and diagnostic
support functions.
7.5 The serial port communication channels shall each be configurable for speeds
of 1200, 2400, 4800 or 9600 bits per second. The physical interface for each serial
port shall support EIA-485 and EIA-232 standards. Each port shall be equipped with
optical protection to provide both galvanic isolation and surge suppression.
7.6 The serial ports shall use MODBUS protocol as a MODBUS slave device. It shall
support both RTU mode and ASCII mode communications. RTU mode shall be used
for communicating with the SCADA/RTU/PLC or the flow computer.
7.7 All operating parameters and flow data shall be accessible via the serial ports.
Analog values retrieved via the serial communication port shall be scaled in
engineering units. IEEE floating format shall be used. Status information shall be
available as either bit packed 16-bit MODBUS holding registers or as single bit
MODBUS data. Operational data shall be user configurable to be in metric units or
imperial units and shall include the following as a minimum:
Uncorrected and corrected forward direction flow rate
Uncorrected and corrected reverse direction flow rate
STANDARD SPECIFICATION FOR SPECIFICATION REV-0
GAIL (INDIA) ULTRASONIC METERS
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NEW DELHI
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