The Natural Gas Composite Sampler: The Most Valuable Instrument at a Custody Transfer Station

13 hours ago

2 min read

At a glance. A custody transfer meter measures volume, but natural gas is bought and sold on energy, and energy comes from the composition of a sample. If the sample is wrong, every invoice is wrong. The Tech Inc. Natural Gas Composite Sampler takes small grabs in proportion to flow and collects them in a constant-pressure cylinder, designed to GPA 2166 and ISO 10715. For a gas custody transfer station, it is one of the best investments it can make.

How it works

The flow computer sends a pulse for each set volume of gas.
The sampler takes a small grab from the probe at the centre of the pipe.
The grab goes into a floating-piston cylinder held at line pressure, so heavy components stay in the gas.
At the end of the period, the cylinder goes to the laboratory and a fresh one goes on.

What is in the system

Insertion probe with isolation valve
Sampling pump or pneumatic sampler
Controller taking the flow signal
Constant-pressure (floating-piston) sample cylinder
Insulated or heated enclosure with gauges, needle valves and relief
Purge and vent connections for safe cylinder changes

Configurations

Version	Use
Flow-proportional	Custody transfer
Time-proportional	Allocation and quality monitoring
Heated enclosure	Rich or wet gas above its dew point
Twin-cylinder	Automatic changeover and retained samples

Why it is one of the best things to happen to gas custody transfer

A sample both sides trust. Grabs paced to flow, not to the clock.
No dew-point loss. The constant-pressure cylinder keeps the heavy ends in the gas.
Safer cylinder changes. Purge and vent connections in the enclosure.
One supplier. Tech Inc. builds the sampler and the constant-pressure cylinders it fills.