The Meter on Your Biggest Customer Is Your Biggest Exposure

A city-gas network is thousands of small connections and a few very large ones. Most of the throughput, and almost all of the billing exposure, sits with a handful of industrial PNG consumers drawing high, variable loads. The economics of the network are decided there. A metering approach adequate for a district station is not automatically adequate for a customer whose monthly bill runs into large sums and who has every commercial incentive to scrutinise it.

District-grade and fiscal-grade are not the same meter

The difference is turndown and defensibility. An industrial consumer’s demand can swing from a night-shift minimum to a full-production peak, and the meter has to stay accurate across that whole range — not just at its design point. A turbine meter to AGA 7 or an ultrasonic meter, correctly sized for the actual load profile rather than the pipe size, holds accuracy where a district-grade device gives up its turndown. The PNGRB technical standards set the framework; matching the meter to the real load is the engineering.

The correction is where bills are won or lost

Gas is bought and sold as energy at standard conditions, but the meter sees actual volume at line pressure and temperature. Without pressure-temperature-compressibility correction — an electronic volume converter applying AGA 8 compressibility — the billed quantity drifts every time line pressure moves. On a large industrial load, an uncorrected or poorly corrected volume is not a rounding error; it is a systematic misbill in one direction, and it is exactly the thing a well-advised customer will eventually contest. Getting the PTZ correction right is not a refinement; it is the invoice.

Defensibility is a documented uncertainty

When a high-volume customer challenges a bill, the operator’s position rests on whether the metering can be shown to be accurate — a stated uncertainty budget, calibration traceability, a correction that can be reconstructed. “The meter is approved” is not an answer to a commercial dispute; a documented measurement chain is. Building that documentation into the industrial custody skid from the start is far cheaper than assembling it under challenge.