D Series Low Pressure Natural Gas Compressor for High-Capacity Industrial Process Service

D Series Low Pressure Natural Gas Compression for High-Volume Industrial Process Service

The D Series covers a broad range of capacities within the low-pressure natural gas compressor product line. Verified models span from 60 to 325 m³/min with discharge pressures from 0.10 to 0.60 MPa, making this series suitable for process duties that require sustained high gas throughput at relatively low discharge pressure. The two-row reciprocating configuration is consistent across the series.

At the lower end of the discharge-pressure range — 0.10 to 0.22 MPa — models are configured as single-stage machines. As discharge pressure increases toward 0.40 and 0.60 MPa, the models in the table transition to a two-stage configuration. This reflects the engineering practice of dividing the overall pressure ratio across two compression stages when the ratio increases, which helps manage cylinder discharge temperatures and maintain acceptable volumetric efficiency at each stage.

Operating Range

Flow capacity in the source data is expressed in m³/min. The flow-reference condition — whether actual volume flow, standard, or normal conditions — must be confirmed with the engineering team before using these values for North American compressor sizing, where SCFM or MMSCFD are the standard references.

Available Models and Technical Specifications

Capacity is expressed in m³/min as stated in the source data. The flow-reference basis (actual, standard, or normal conditions) must be confirmed with the engineering team for accurate North American sizing in SCFM or MMSCFD. Pressure values are as stated in the source material; gauge/absolute basis should be confirmed before engineering use.

Two-Row Configuration and Stage Selection

The two-row reciprocating configuration in the D Series means the machine has two opposing cylinder banks. At the lowest discharge pressures — 0.10 to 0.22 MPa — the overall compression ratio from suction to discharge is relatively low, and single-stage compression is sufficient to handle this ratio within acceptable temperature limits. The single-stage models in this series handle capacities up to 325 m³/min.

As discharge pressure increases to 0.40 and 0.60 MPa, the two-row machine transitions to a two-stage arrangement. In two-stage compression, the gas is compressed in the first cylinder to an intermediate pressure, then passed to the second-stage cylinder to reach the final discharge pressure. This distribution of compression duty reduces the temperature rise at each stage and allows the machine to handle a higher overall pressure ratio without exceeding temperature limits that would affect cylinder valve life and gas integrity.

Process Gas Applications

The capacity range of the D Series makes it applicable to process duties that require sustained high gas volumes at low to moderate discharge pressures. Relevant applications may include gas gathering operations where field gas is collected and moved at low pressure to a central processing point, process compression within a gas treatment facility, pipeline pressure maintenance at low differential, and booster service between process vessels operating at low pressures.

The high-voltage electrical supply (6 kV or 10 kV) available on most D Series models reflects the large motor power involved — from 315 kW on the smaller models up to 1,100 kW on the highest-capacity units. At these power levels, 380 V supply would require impractically large cabling, and high-voltage motors are the standard choice for industrial compressor installations of this scale.

The physical size of the D Series machines — frame lengths of 5,000 to 6,500 mm and weights ranging from approximately 6.8 to 18 tonnes — places these units firmly in the category of industrial plant equipment. Site preparation, structural foundation design, and crane access for installation and major maintenance should be considered early in the project.

Suction Conditions and Gas Composition

Compressor sizing cannot be completed from the discharge pressure and nominal capacity values in the table alone. Suction pressure has a direct effect on the actual volumetric flow the machine must handle. If suction pressure is substantially below atmospheric, the inlet gas density is lower than assumed, and the actual machine displacement required to achieve the stated mass or standard-flow capacity increases. Conversely, if suction pressure is elevated, the machine may deliver more flow at a lower compression ratio than the stated discharge pressure would imply.

Gas composition affects several aspects of compressor selection. Heavier hydrocarbon content raises the gas molecular weight and affects compressibility. CO₂ and H₂S, if present in significant concentrations, raise corrosion concerns for cylinder metallurgy, piston rings, valves, and seal materials. Any process gas with elevated sour-gas components requires explicit disclosure before a machine is selected. Water content and the potential for liquid dropout in the suction piping are also important — reciprocating compressors are not designed to ingest liquid slugs, and adequate knockout vessels or separators upstream of the suction nozzle are standard practice.

Package Configuration

A reciprocating natural gas compressor of this size is typically supplied as a complete compressor package on a fabricated steel skid. The package integrates the compressor unit, driver (electric motor in most configurations shown in the table), power transmission, and the associated process piping, separators, coolers, instrumentation, and control panel. The overall package dimensions and weight will be larger than the bare-compressor dimensions shown in the specification table above.

Package scope — including which components are supplied as part of the skid-mounted package versus which are provided by the buyer’s project — should be established early. For export projects, shipping dimensions and method of transport (containerized, open-frame, or heavy-lift) also affect package design.

Selecting the Correct D Series Model

Model selection within the D Series starts with the required discharge pressure and required gas volume. Once those parameters narrow the relevant pressure band, the suction pressure and gas composition determine whether the stated nominal capacity is achievable at the operating condition. Motor power requirements are also site-dependent: ambient temperature and elevation affect motor cooling and may require derating. High-voltage supply availability must be confirmed for the project site, as most D Series models require 6 kV or 10 kV electrical infrastructure.

Where the required capacity falls between two listed models, the engineering team should be consulted. Custom configurations within the product-line capability range may be possible, and adjacent models often differ in cylinder bore or stroke rather than in overall frame size.

Information Required for Compressor Selection

• Gas composition (component breakdown)
• Methane, CO₂, and H₂S content
• Suction pressure and suction temperature
• Required discharge pressure
• Required gas flow rate and flow-reference basis (actual, standard, or normal conditions)
• Site ambient temperature range
• Installation altitude
• Continuous or intermittent duty cycle
• Available electrical supply voltage and frequency
• Cooling availability (air-cooled or water-cooled)
• Hazardous-area classification requirements
• Skid and package requirements
• Destination country and project site location

Frequently Asked Questions

Why do D Series models at 0.40 MPa use two-stage compression when 0.10 MPa models are single-stage?
The number of compression stages is driven by the overall compression ratio — the ratio of absolute discharge pressure to absolute suction pressure. At very low discharge pressures and typical suction conditions, the ratio is low enough that a single compression stage can handle the required pressure increase without excessive discharge temperature. As the target discharge pressure increases to 0.40 or 0.60 MPa, the compression ratio rises, and two-stage compression becomes the appropriate configuration to manage stage temperatures and maintain cylinder valve performance.

Can the D Series compress gas with H₂S or CO₂ present?
Gas composition — including acid gas content — must be disclosed during the inquiry stage. The presence of H₂S or elevated CO₂ affects material selection for cylinders, valves, piston rings, and seals. The engineering team will evaluate the composition and advise on suitability and any material upgrades required. Do not assume standard materials are suitable for sour-gas service without explicit confirmation.

What does the 6K or 10K voltage designation mean?
6K and 10K refer to a 6 kV or 10 kV motor supply voltage. At the power levels required by medium-to-large D Series models — 550 to 1,100 kW — high-voltage motors are standard. The appropriate voltage depends on the electrical infrastructure available at the installation site. The engineering team should receive confirmation of site voltage and frequency before finalizing the motor selection.

Is the capacity value in m³/min an actual-flow figure or a standard-flow figure?
The source data does not specify the reference condition for the capacity values. North American gas compressor sizing typically requires flow in SCFM (standard cubic feet per minute) or MMSCFD referenced to standard conditions. Before using these figures for project sizing, the flow-reference basis should be confirmed with the engineering team to avoid errors in machine selection.

Request a Technical Proposal

To evaluate whether a D Series model fits your operating conditions, the engineering team requires gas composition, suction pressure and temperature, required discharge pressure, required gas flow rate with the flow-reference basis, and site conditions including altitude and ambient temperature. With this information, the team can review compression ratio, stage arrangement, motor selection, and package configuration, then prepare a technical proposal covering equipment scope, dimensions, power requirements, and delivery terms.

Related Compressor Products

• H Series Low Pressure Natural Gas Compressor — four-row configuration, capacities up to 600 m³/min
• L Series Low Pressure Natural Gas Compressor — lower-capacity two-row units suitable for smaller-volume process service
• 4M Series Low Pressure Natural Gas Compressor — four-row two-stage design at 180–240 m³/min
• D Series High Pressure Natural Gas Compressor — medium-capacity high-pressure process service
• Natural Gas Compressor — full product line overview