A natural gas station is built from separate functional blocks: filtration, preheating, pressure regulation, metering and gas quality measurement. Which of them a station needs depends on four things: how far the pressure has to drop, how clean and stable the gas is, what the measurement will be used for, and what the downstream user requires. A station at a factory inlet may be nothing more than a meter run, while a transmission-to-distribution interface can combine filtration, preheating, staged regulation, custody transfer metering and odorization in one facility.
This page works as a decision map: it outlines the functional blocks and points you to the solution page that matches your requirement.
Functional blocks along the gas path
The sequence can change from project to project. Whether metering sits upstream or downstream of regulation, for example, depends on the contractual delivery point and on meter sizing. A typical arrangement looks like this:
1. Inlet isolation: valves that separate the station from the pipeline for maintenance or in an emergency.
2. Filtration: removes solid particles and liquid droplets to protect regulators, valves and meters.
3. Preheating: offsets the cooling that accompanies pressure reduction (the Joule-Thomson effect) and is placed ahead of the regulators.
4. Pressure regulation and overpressure protection: regulators hold the outlet pressure at set point, while slam-shut and relief valves protect the downstream system.
5. Metering: a meter, pressure and temperature measurement, and a volume corrector or flow computer convert the quantity at line conditions to base conditions or to energy.
6. Gas quality measurement: composition, calorific value, dew point and sulfur compounds are monitored for energy-based billing or to meet a consumer specification.
7. Outlet and auxiliary systems: odorization, remote monitoring and the control panel are added according to the station's role.
Few stations include every block. A delivery point with no pressure reduction has no heating or regulation, and a site receiving gas of stable composition may not need continuous analysis. Scope should therefore be derived from process data rather than from a standard equipment list.
Matching your requirement to a solution
Starting requirement | Key function | Relevant solution |
Determine the quantity consumed or delivered without changing pressure | Meter run, volume conversion | Natural gas metering stations |
Supply a consumer from a high-pressure line at usable pressure and meter at the same point | Regulation, protection chain, metering | Pressure reduction and metering stations (RMS / PRMS) |
Establish a billing quantity that all parties can accept | System uncertainty, verification, audit trail | Custody transfer metering stations |
Wide rangeability and diagnostics on high-flow lines | Multipath ultrasonic metering | Ultrasonic metering skids |
Differential pressure metering or continued use of existing orifice assets | Orifice and DP transmitter chain | Orifice metering skids |
Protect meters and regulators from contaminants | Filtration, differential pressure monitoring | Filtration and metering skids |
Pressure control only, with no metering duty | Regulator, slam-shut, relief | Pressure regulating skids |
Manage gas cooling across a large pressure drop | Preheating, regulation, metering | Heating, regulating and metering skids |
Continuous monitoring of calorific value, composition or contaminants | Gas analysis, sample conditioning | Gas quality analysis systems |
Meet a gas turbine or engine fuel gas specification | Conditioning, heating, consumption metering | Fuel gas conditioning and metering skids |
Hand over gas from transmission to a city distribution network | Heating, staged regulation, metering, odorization | City gate stations |
Three questions that narrow the choice
Three questions usually get the selection started. First, pressure: if the inlet pressure is above what the downstream system can accept, a regulating block is needed, and the larger the pressure drop, the more attention cooling and preheating deserve. Second, purpose: in-plant monitoring and billing for gas that changes hands may use similar hardware, yet their verification, redundancy and record-keeping requirements differ markedly. Third, the gas and its user: contaminant load drives filtration, while energy-based billing or a machine fuel specification drives analysis and conditioning.
Gas sent out from LNG terminals
At liquefied natural gas (LNG) import terminals, custody metering of the gas delivered to the grid normally takes place in the gas phase, downstream of the vaporizers. A send-out metering point therefore has more in common with the gas stations described here than with cryogenic liquid metering.
How TLY Enerji supports these projects
TLY Enerji provides engineering support from the review of process conditions through the selection of measurement and control technology. Depending on project scope, this can extend to supply of measurement and analytical equipment, system integration, site installation, PLC- or SCADA-based monitoring, testing, commissioning and maintenance support. The functional blocks included in the scope of supply are agreed case by case against the technical specification.
Solutions in this category
· Natural gas metering stations: Meter run architecture and volume conversion.
· Pressure reduction and metering stations (RMS / PRMS): Regulation and metering combined in one station.
· Custody transfer gas metering stations: What billing-grade measurement demands.
· Ultrasonic gas metering skids: Meter runs built around multipath ultrasonic meters.
· Orifice gas metering skids: Metering based on differential pressure.
· Gas filtration and metering skids: Protecting equipment from contaminants.
· Gas pressure regulating skids: Selecting regulators and protection devices.
· Gas heating, regulating and metering skids: Handling cooling across pressure reduction.
· Natural gas quality analysis systems: Composition, calorific value and contaminants.
· Fuel gas conditioning and metering skids: Turbine and engine fuel gas requirements.
· City gate stations: The transmission-to-distribution interface.
· LNG send-out metering: Gas-phase metering after regasification.
Frequently asked questions
Should metering come before or after pressure regulation?
There is no single correct order. Metering upstream of regulation means the meter operates at higher pressure and sees a smaller actual volume; metering downstream means lower pressure and a larger actual volume for the same gas. The decision rests on the contractual delivery point, meter size, pressure class and any influence the regulators may have on the measurement.
Is an RMS the same as a city gate station?
Both reduce pressure and meter gas, but they play different roles. A city gate station sits at the interface between a transmission pipeline and a distribution network and also carries network functions such as odorization. An RMS or PRMS typically serves a specific consumer or delivery point, such as an industrial plant, an industrial zone or a power station.
Does every gas station need a heater?
No. Heating needs are assessed from the size of the pressure drop, the inlet gas temperature and the gas composition. Stations without regulation, or with only a small pressure drop, may need no heater. Where the drop is large, preheating keeps the outlet temperature within limits acceptable to the equipment and the downstream system.