DPC units are designed to be installed directly on a stable surface. Good quality soil fill should be used to build up to a non-flooding elevation. A gravel, crushed concrete, or caliche cap should be considered to stabilize the surface.

The skid should be relatively level to ensure proper operation: Two (2) inches maximum out of level along the long axis of the skid, and one (1) inch across the width of the skid. Do not allow the skid to be twisted by an uneven support. This may put the equipment and piping in a bind and create undue stress on pressure retaining components. The greatest weight is under the heat exchanger support beams; therefore, the most benefit will be obtained by supporting these beams from the pad.

Connecting Piping

Connecting piping should be supported to keep loads on equipment nozzles and skid connections to less than 200 pounds each. DPC maintains inlet and outlet gas flange connections on the same end of the skid to simplify unit size change outs.

Inlet and Outlet Gas Connection Sizes:

Model A3 inch 600# ANSI raised face flange
Model B4 inch 600# ANSI raised face flange
Model C6 inch 600# ANSI raised face flange
Model D6 inch 600# ANSI raised face flange

Liquid dump lines from all skids are one inch screwed schedule 80 pipe.

Electrical Classification

The process skid has a Class I Group D Division 1 Electrical Area Classification due to the presence of instrument and power gas, which vents continuously (unless an instrument air system is provided.) This must be considered when locating other electrical or flame-fired equipment in the area of the skid to ensure safe operations. No smoking or any other open flames should be permitted in the immediate vicinity of the unit.


The fundamentals of a good layout and design cannot be overemphasized. They provide an irreplaceable safety factor throughout the life of the project, often at very little increase in initial cost. DPC equipment is specially designed to remove the heavier hydrocarbon components from natural gas. Unlike methane, these gaseous components are all heavier then air and must be treated differently than methane. The DPC refrigeration chiller packages are non-electrically classified and must be spaced safely from combustion sources. Industrial risk guidelines in practice all over the world use the OIA/RIA gasoline plant spacing charts. Although a closely spaced facility may meet the letter of the law of the NEC or API codes, it is not considered best engineering practice. The buyer must beware; many engineers and even some of our competitors confuse the application of the various standards, recommendations and codes. Usually a judicious equipment layout will show that the open electrical, usually located in a corner of a typical lease or facility plot, will also be convenient to locate other sources of combustion, such as glycol reboiler burners or incoming power infrastructure.

Unit Performance

Performance of the unit to achieve the specified dew point of the sales gas (cold separator temperature) is dependent on:

  • Inlet gas composition
  • Inlet gas temperature
  • Differential pressure across the JT valve
  • Proper operation of the JT unit equipment

Be advised that a JT unit is sensitive to inlet gas temperature. The performance guarantee for hydrocarbon dew point is only valid up to the maximum inlet temperature given to DPC when sizing the unit for the specific lease. If the inlet gas temperature rises above the design temperature, the sales gas dew point specification may not be achieved. Contact DPC if this occurs, or is anticipated to occur, for assistance in troubleshooting the installation.

The standard DPC JT unit is provided with a pressure controller to set the JT valve to the required upstream pressure. If the transporting pipeline varies widely in pressure, provision must be made to stabilize either the differential pressure across the skid/JT valve or to stabilize the unit’s outlet pressure.

DPC provides a hot gas bypass and valve on the JT unit to assist in thawing the unit, or it can be used to reduce process temperature temporarily until pressure control can be stabilized.

The DPC Mini JT unit was specifically engineered to operate in the 200 to 1,000 MSCFD range. Due to the small size, DPC worked hard to reduce the costs associated with this unit and thus the Mini JT does not have the same instrumentation as the larger DPC units.

Contact DPC for assistance, if needed, on any of the above issues.

Lessee is expected to provide proper overpressure safety system protection to prevent pressuring the DPC unit above 1440 psig. DPC provides an inlet gas safety relief valve connection for the Lessee’s use if needed. The relief valve supplied by DPC is only designed for thermal relief protection.