© 2019 Department of Petroleum Resources. All rights reserved Department of Petroleum Resources (DPR) PROCEDURE GUIDE

Page 99 of 114

98 | P a g e

1.20.3.2.3 Interface Requirements

The system shall be controlled and monitored from the measurement computer or SAS.

1.20.3.3 Technical requirements

1.20.3.3.1 Initial selection of automatic probe location
The sample point shall be chosen to provide a representative sample of the flowing gas
in the pipe.
The sampling point shall be installed at least 20 diameters downstream of the nearest
bend or restriction on a horizontal pipe. The probe shall be installed in a 10 - 2 o'clock
position.
1.20.3.3.2 Probe design

The probe shall be a pilot tube type extending into the centre one-third of the pipeline
diameter. In addition, the sampling probe should be possible to retract under operating
pressure by method accepted by the operator.

1.20.3.3.3 Sample collection pump

There shall be two parallel sample collection pumps, which shall be self-purging and can
operate under line conditions. The grab size volume shall be adjustable in the range 0.5
– 1.5 ml.
The sample collection pumps shall be located above and as close to the probe as is
practically possible. Filters, drip pots, screens, regulators and such conditioning
equipment shall not be placed between the probe and the sampler.

1.20.3.4 Sample receiver

• There shall be two parallel sample receivers.

• The filling of the two sample receivers shall have a maximum deviation of ± 5 %.

• Heat tracing and insulation shall be provided to keep the temperature minimum
10 ° C above the condensation temperature.

• The receivers shall be of the floating piston type with back-pressure of an inert
gas.

• The receivers shall be equipped with a local piston position indicator and a limit
switch for maximum filling.

1.20.3.5 Tubing and valves

• The temperature in all parts of the sample lines/tubing and sample receivers
shall be kept at a temperature minimum 10 ° C above the hydrocarbon dew point
temperature.

• The valves for the sampling system shall be of type full-bore ball valves.

• The sample tubing from/to the main pipe should have a slope of at least 1:12 to
avoid liquid traps.

1.20.3.6 Back-pressure system

There shall be a back-pressure system with inert gas (argon or helium). This shall include
a booster facility. The back-pressure volume shall be at least five times larger than the
receiver volume and of a size so that the pressure increase caused by 100% sample filling
is less than 10 bar.