standard specification for erection tender - GAIL

egulating the sample pressure & flow. The sample flow should be controlled by a needle valve
and flow should be indicated through Rota meter. The enclosure for calibration gas system
should have heating system with insulating jacket (uniformly to all parts of cylinders) so as to
maintain minimum temperature required for stability of certified composition. The sample
conditioning system should be field mounted & adjacent to the sampling point of the pipeline.
Analyzer Unit and Programmable control Unit
The function of this unit will be to analyze the gas sample, do the calculation of Heating Value,
Relative Density (specific gravity), Compressibility Factor etc. and provide information to
interface / display unit. The technical details of this unit are given as under:
i. Type: Continuous On-line Gas Chromatograph
ii. No. of streams: single stream
iii. a) Column: Micro pack / MEMS column with high resolution and low carrier gas
consumption
b) Column size (length / diameter): By vendor
iv. Detector: Thermal conductivity detector
v. Carrier gas:
a) Ultra-pure Helium gas along with pressure regulators and Rota Meter flow-indication.
The consumption of carrier gas should be as low as possible.
b) Flow rate: the minimum possible (to be defined by the bidder)
vi Cycle time: Operator / user assignable (5 minutes maximum).
vii. Analyser:
a) The design of Analyser should be based on solid-state electronics with protection
from industrial EMI /RFI Interference.
b) Inputs / Outputs: It should communicate digitally to interface / display unit to send
the analysis related information.
c). Analyzer & analyzer electronics should be supplied with prefabricated / installed
tube connection etc., so that field tubing etc. to be done as minimum as possible
at site for connection of sample line & carrier gas and calibration gas cylinders
d) Functions: Control of all analysis functions in a cycle from operation of sampling
valves to detection of peaks and precise calculations for peak measurements,
area integration and internal normalization. Average values of analysis and
computed results for 8 and 24 hours shall be available automatically or on demand.
Also generation of gas analysis report (scheduled or on-demand) and
average report (8 hourly average, 24 hourly averages) for gas composition,
calorific values and specific gravity.
viii. Calibration: Automatic calibration with user selectable time intervals or manually on
demand as & when required. To accurately determine the relative response factors
with/without single component calibrations such as high purity methane. Vendor shall indicate
the accuracy and repeatability of the measurement achieved by the calibration method
adopted. Also during calibration period the stream composition data of previous analysis shall
be used in Flow computer. Also if the calibration results are out of range then it shall be
alarmed. The composition data during alarm condition shall be rejected and shall not be used
for Flow computation.
GAIL (INDIA) LTD
NEW DELHI
JOB SPECIFICATION FOR GAS METERING
SYSTEM / SKID
JOB SPECIFICATION REV-0
0015-01-08-02-001
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