D Series High Pressure Natural Gas Compressor — Three-Stage and Four-Stage Reciprocating Process Compression

D Series High Pressure Natural Gas Compression — Three-Stage and Four-Stage Reciprocating Process Service

The D Series high pressure natural gas compressor covers the medium-capacity segment of the high-pressure product line. Verified models handle 25 to 70 m³/min at discharge pressures of 2.50 to 4.00 MPa. The series includes both three-stage and four-stage configurations, and several models are available at dual discharge-pressure ratings — 3.00 or 4.00 MPa — allowing a single machine type to serve either pressure level with differing power requirements. This is the broadest model range in the high-pressure compressor family.

Most D Series high-pressure models require a 6 kV or 10 kV electrical supply, reflecting the 280 to 850 kW motor power range involved at the higher capacity levels. A subset of models — those at the lower end of the range — list 380 V or combined 380/6K options, which may suit sites where high-voltage infrastructure is limited.

Operating Range

Capacity values are in m³/min as stated in source data. Flow-reference basis must be confirmed for North American sizing. Several models carry dual discharge-pressure ratings (3.00 or 4.00 MPa); these are presented with both values in the table below.

Available Models and Technical Specifications

* DW-30/30 (both configurations) shows 25 m³/min capacity in the source data despite the model number notation implying 30. The source value is retained as published. Dual pressure and dual power values (e.g. 3.00 or 4.00 MPa; 550 or 600 kW) indicate the same model is rated for either discharge pressure with a corresponding difference in motor power. Capacity in m³/min; flow-reference basis must be confirmed. Pressure as stated; gauge/absolute basis must be verified.

Three-Stage Versus Four-Stage: Why Both Configurations Exist

The D Series high-pressure product line includes both three-stage and four-stage configurations, and in some cases — the DW-25/30, for example — both a three-stage and a four-stage variant exist for the same model at the same discharge pressure. This reflects the fact that stage count is not determined purely by the discharge pressure. The actual operating compression ratio, suction temperature, gas composition, and design constraints on per-stage pressure ratio all influence whether three or four stages are optimal for a given application.

A four-stage configuration distributes the overall compression ratio across four steps, each handling a lower individual ratio than three stages at the same overall pressure. Lower per-stage ratios reduce the discharge temperature of each cylinder, extend valve life, and reduce the power required per stage. However, four-stage machines involve more interstage coolers, additional piping, and greater mechanical complexity. Whether three or four stages is the appropriate configuration for a specific operating condition depends on the full set of suction and discharge parameters, and should be evaluated by the engineering team once operating conditions are confirmed.

For the dual-pressure models — DW-50/30(40), DW-60/30(40), and DW-70/30(40) — the same mechanical frame handles either a 3.00 MPa or 4.00 MPa discharge pressure, with a corresponding difference in motor power. This allows the project team to defer the final pressure specification or to use a common machine type across projects that require different discharge pressures within this range.

Discharge Temperature and Interstage Cooling

At discharge pressures of 2.50 to 4.00 MPa, managing discharge temperature is an important engineering consideration. In a reciprocating compressor, the temperature of the gas leaving each compression stage is determined by the inlet temperature, the compression ratio of that stage, and the properties of the gas. If any stage inlet temperature is too high — because the interstage cooler was undersized or the ambient temperature was higher than anticipated — the final discharge temperature of the last stage increases, which affects downstream piping design, gas-phase behavior, and cylinder valve performance.

For high-pressure D Series machines in hot climates or high-altitude environments where air-cooled heat exchangers have reduced cooling capacity, the engineering team should evaluate interstage temperatures during detailed design to confirm that the cooling arrangement meets the required inlet temperatures at each stage under the worst-case ambient condition expected at the installation site.

Applications

The 25 to 70 m³/min capacity range and 2.50 to 4.00 MPa discharge pressure position the D Series high-pressure compressor for process and pipeline duties at medium industrial scale. Gas gathering systems that require compression to pipeline pressures in the 3.00 to 4.00 MPa range — typical for higher-pressure trunk or gathering pipelines — are a natural fit where the required gas volume matches the series range. Gas processing plant compression service, where treated gas must be recompressed to meet a downstream pressure specification, is another application. Pipeline booster service where an existing line has experienced pressure drop and requires localized pressure restoration is also applicable where the required capacity is within the 25 to 70 m³/min range.

Information Required for Compressor Selection

• Gas composition (full component breakdown)
• Methane, CO₂, and H₂S content
• Suction pressure and suction temperature
• Required discharge pressure (3.00 MPa or 4.00 MPa where a dual-pressure model is under consideration)
• Required flow rate and flow-reference basis
• Site ambient temperature range and altitude
• Continuous or intermittent duty cycle
• Available electrical supply (voltage and frequency)
• Cooling method (air-cooled or water-cooled)
• Hazardous-area classification requirements
• Preference for three-stage or four-stage configuration if applicable
• Skid and package requirements
• Destination country and project site

Frequently Asked Questions

When should I specify a four-stage D Series machine instead of three-stage?
Stage count is a function of the actual compression ratio, gas composition, and acceptable per-stage discharge temperature limits, not just the discharge pressure. At 3.00 MPa discharge with near-atmospheric suction, a three-stage configuration may be sufficient for typical natural gas compositions. For operating conditions that produce higher compression ratios per stage — elevated suction temperature, gas composition with a higher specific heat ratio, or requirements for lower final discharge temperature — four-stage compression distributes the duty more finely and reduces the temperature rise at each stage. The engineering team evaluates this based on the confirmed operating parameters.

What does the dual pressure notation DW-50/30(40) mean?
The notation indicates that this model is designed and rated for either 3.00 MPa or 4.00 MPa discharge pressure. The power values — 550 kW at 3.00 MPa and 600 kW at 4.00 MPa — reflect that more compression work is required to reach the higher pressure with the same gas flow. Both pressure options share the same mechanical frame, which can simplify procurement and spare-parts management across projects that require different delivery pressures within this range. The specific configuration for either pressure option should be confirmed at the time of order.

Why does the DW-60/30(40) have a much larger footprint than adjacent models?
The DW-60/30(40) lists dimensions of 8,500 × 2,400 × 3,020 mm and weighs 17.00 tonnes, which is notably larger than the DW-50 and DW-70 units at similar configurations. This likely reflects a different cylinder arrangement or frame design required to accommodate the 60 m³/min capacity and the dual-pressure rating within the physical constraints of the two-row four-stage layout. The engineering team can advise on the specific design reason and confirm installation space requirements for this model.

Request a Technical Proposal

With the broadest model range in the high-pressure natural gas compressor family — thirteen verified units across three-stage and four-stage configurations at capacities from 25 to 70 m³/min — the D Series high-pressure line can cover a wide range of medium-capacity process duties. To determine the appropriate model and stage configuration for your operating conditions, provide gas composition, suction pressure and temperature, required discharge pressure, required flow rate with the flow-reference basis, site conditions, and electrical supply details. The engineering team will review the compression parameters, confirm stage selection, and prepare a technical proposal.

Related Compressor Products

• 4M Series High Pressure Natural Gas Compressor — four-row four-stage, highest-capacity high-pressure models at 85–150 m³/min
• L Series High Pressure Natural Gas Compressor — two-row multi-stage, lower-capacity models at 6–25 m³/min
• Natural Gas Compressor — full product line overview