LNG transfer pumps are used to move liquefied natural gas between storage, processing and transportation systems while maintaining the fluid under the required cryogenic conditions.

Depending on the facility and process configuration, LNG pumping applications may include:

• transfer between LNG storage tanks,
• LNG tank filling and withdrawal,
• transfer from storage to downstream process equipment,
• LNG circulation and recirculation,
• loading and unloading operations,
• transfer to vaporization or regasification systems,
• LNG handling within terminals and industrial facilities,

Selecting an LNG transfer pump requires careful consideration of flow rate, total dynamic head, operating pressure, LNG temperature, vapor pressure, available NPSH and the configuration of the storage and transfer system.

Because LNG is stored close to its boiling point, pressure losses or excessive heat input can lead to flashing and vapor formation. Pump hydraulics, suction conditions and thermal behavior must therefore be evaluated together to maintain stable operation.

For LNG terminals, storage facilities and industrial installations, pump reliability is also a major consideration. Equipment may be expected to operate under demanding conditions while minimizing leakage risks, maintenance requirements and potential interruptions to LNG handling operations.

Submersible LNG pumps provide an effective solution for transferring liquefied natural gas directly from cryogenic storage tanks.

Unlike a conventional external pump installation, a submersible cryogenic pump can be installed directly inside the LNG storage tank and immersed in the pumped liquid.

OPTIMEX has developed a fully submerged canned motor pump configuration in which the pump and electric motor operate within the cryogenic liquid. This architecture allows the pumping system to be integrated into the storage tank while eliminating the need for a conventional rotating shaft penetration and dynamic shaft seal.

An in-tank configuration can provide several advantages for LNG storage and transfer applications:

• direct installation within the LNG storage tank,
• reduced need for liquid connections at the bottom of the tank,
• improved containment of the cryogenic liquid,
• reduced external piping associated with pump suction,
• operation under challenging suction conditions,
• suitability for applications with low available NPSH,
• ability to support low liquid-level operation depending on pump configuration,

For applications where suction conditions are particularly demanding, hydraulic design can also incorporate an inducer to reduce the pump’s NPSH requirements.

This type of in-tank LNG pump configuration can be particularly relevant for LNG storage facilities and other cryogenic tank applications where minimizing external leakage paths and maintaining efficient liquid withdrawal are important design considerations.

A sealless LNG pump eliminates one of the potential leakage points found in conventional centrifugal pump designs: the dynamic mechanical shaft seal.

In a canned motor LNG pump, the pump and motor form an integrated hermetically contained unit. There is no conventional shaft seal between the pump casing and the external environment.

This architecture offers significant advantages when handling a volatile and flammable cryogenic fluid such as LNG.

The absence of a dynamic mechanical seal helps:

• minimize potential LNG leakage paths,
• improve fluid containment,
• reduce maintenance associated with mechanical seals,
• provide a compact pump-and-motor arrangement,
• support submerged or specialized cryogenic configurations,
• improve reliability for critical LNG transfer applications,

OPTIMEX cryogenic technology uses a wet-stator motor design in which the stator and rotor operate immersed in the pumped cryogenic liquid. This differs from conventional canned motor designs using a stator liner or can between the fluid and the stator.

For cryogenic service, this architecture allows the pumped liquid to participate directly in motor cooling while avoiding a conventional mechanical seal.

The combination of sealless pump technology, cryogenic engineering and submerged pump configurations makes canned motor technology particularly relevant for demanding LNG applications where containment, low-temperature performance and operational reliability are key project requirements.

Liquid nitrogen pumps, also referred to as LN2 pumps or cryogenic nitrogen pumps, are designed to transfer nitrogen maintained in its liquid state at approximately -320°F at atmospheric pressure.

Liquid nitrogen is one of the most widely used cryogenic fluids in industry and may be required for cooling, freezing, inerting, process control, testing and other low-temperature operations.

Depending on the process, LN2 pumps can be used for applications such as:

• liquid nitrogen storage and transfer,
• tank filling and withdrawal,
• industrial gas production and distribution,
• cryogenic process cooling,
• food freezing and chilling systems,
• metal processing and heat treatment,
• electronics and semiconductor manufacturing,
• laboratory and industrial testing,
• aerospace testing and environmental simulation,
• cryogenic process systems,

Because liquid nitrogen is stored close to its boiling point, LN2 transfer pumps must be engineered to limit heat input and vapor formation while maintaining the required hydraulic performance.

Flow rate, total dynamic head, operating pressure, available NPSH, storage tank configuration and duty cycle are therefore important parameters when selecting a liquid nitrogen transfer pump.

For applications requiring enhanced fluid containment, a sealless liquid nitrogen pump eliminates the conventional dynamic shaft seal and provides an alternative to mechanically sealed pump configurations.

Liquid oxygen pumps, commonly referred to as LOX pumps, are used to transfer oxygen in its liquid state at approximately -297°F at atmospheric pressure.

Liquid oxygen is used in a wide range of industrial and specialized applications, including industrial gas production, Air Separation Units (ASUs), metallurgy, chemical processing, medical gas supply, aerospace and space applications.

LOX service requires particular attention because oxygen is a strong oxidizer. Pump design and material selection must therefore account not only for cryogenic temperatures but also for oxygen compatibility, cleanliness and application-specific safety requirements.

Potential applications for cryogenic oxygen pumps include:

• liquid oxygen storage and transfer,
• industrial gas production facilities,
• Air Separation Units,
• LOX tank filling and withdrawal,
• process oxygen supply systems,
• metallurgy and steelmaking,
• specialized testing facilities,
• aerospace applications,
• space and propulsion-related systems,

Selection of a liquid oxygen transfer pump must consider the complete operating envelope, including temperature, pressure, flow rate, total dynamic head, NPSH, material compatibility and installation configuration.

For critical LOX applications, the suitability of the pump materials, components and manufacturing procedures must be specifically evaluated for oxygen service and the applicable project requirements.

Liquid argon pumps, also known as LAr pumps or cryogenic argon pumps, are designed to handle argon at approximately -303°F at atmospheric pressure.

Liquid argon is produced primarily through air separation and is widely used in industries requiring an inert atmosphere or high-purity industrial gas.

Applications for liquid argon transfer pumps can include:

• liquid argon storage and transfer,
• Air Separation Units,
• industrial gas production and distribution,
• tank filling and withdrawal,
• metallurgy and welding applications,
• electronics and semiconductor manufacturing,
• specialty gas systems,
• research and scientific facilities,
• other high-purity cryogenic processes,

As with other liquefied gases, maintaining stable liquid conditions is an important consideration when pumping LAr. Pump selection must take into account vapor pressure, suction conditions, available NPSH, flow rate, total dynamic head and heat input.

A properly engineered LAr pump must also be compatible with the purity requirements of the application and the operating conditions of the cryogenic storage or process system.

For installations where leakage prevention and reduced seal maintenance are important, sealless cryogenic pump technology can provide an attractive solution by eliminating the conventional dynamic mechanical seal.

Cryogenic pumping requirements extend beyond nitrogen, oxygen and argon. Many industrial, energy and chemical processes involve refrigerated or liquefied gases that require specialized pumps for storage, transfer, circulation or process applications.

Depending on the required operating conditions and fluid properties, cryogenic pumping technologies may be considered for fluids such as:

• liquid methane and liquefied natural gas (LNG),
• ethylene,
• propylene,
• liquefied petroleum gas (LPG),
• other refrigerated hydrocarbons,
• other liquefied industrial gases and low-temperature process fluids.

Each fluid presents its own combination of temperature, vapor pressure, density, viscosity, flammability, chemical compatibility and containment requirements.

A pump designed for one cryogenic liquid therefore cannot automatically be assumed to be suitable for another.

OPTIMEX evaluates cryogenic pump applications according to the characteristics of the pumped fluid and the required operating conditions, including minimum and maximum temperature, suction pressure, discharge pressure, flow rate, NPSH, installation configuration and materials compatibility.

For volatile, flammable or difficult-to-contain liquefied gases, sealless and canned motor pump technologies can provide an important advantage by eliminating the dynamic mechanical seal and reducing potential leakage paths.

This engineered approach enables the pump configuration to be adapted to the specific requirements of industrial gas plants, cryogenic storage facilities, process plants, LNG infrastructure and other critical low-temperature applications.

LNG terminals require reliable cryogenic pumping equipment throughout liquefied natural gas storage, transfer and handling operations.

LNG may need to be transferred between process equipment and storage systems, withdrawn from cryogenic tanks or moved toward downstream handling and regasification systems.

Depending on the terminal configuration, LNG pumps and cryogenic transfer pumps can support applications such as:

• LNG storage tank filling and withdrawal,
• transfer between cryogenic storage tanks,
• LNG circulation and recirculation,
• loading and unloading operations,
• transfer within LNG terminal infrastructure,
• supply to downstream process equipment,
• transfer toward vaporization or regasification systems,
• other LNG storage and handling duties,

LNG terminal pumps must operate under demanding cryogenic conditions while managing the challenges associated with low temperature, fluid vaporization, NPSH and containment of a volatile and flammable liquid.

For storage applications, submersible LNG pumps and in-tank cryogenic pumps can provide an alternative to externally mounted equipment. Installing the pumping unit within the cryogenic storage tank can reduce external suction piping and help address installations with limited available NPSH.

Sealless LNG pump technology also eliminates the conventional dynamic mechanical seal, reducing potential leakage paths in applications where containment and operational reliability are major requirements.

These characteristics make cryogenic pump engineering relevant across LNG storage facilities, import and export terminals, energy infrastructure and other liquefied natural gas handling installations.

LPG pumps, or liquefied petroleum gas pumps, are used to transfer pressurized liquefied hydrocarbons such as propane, butane and LPG mixtures in storage, processing and distribution systems.

Unlike many cryogenic industrial gases, LPG can generally be maintained in liquid form under pressure at ambient or moderately refrigerated temperatures. However, its high volatility, flammability and tendency to vaporize when pressure drops create demanding requirements for pump selection, fluid containment and suction conditions.

Depending on the process and installation, LPG transfer pumps may be required for applications such as:

• LPG storage tank transfer and withdrawal,
• transfer between storage vessels,
• loading and unloading systems,
• LPG processing and distribution facilities,
• propane and butane transfer,
• refrigerated LPG handling,
• circulation and process duties,
• petrochemical and energy infrastructure,

Because LPG has a relatively high vapor pressure, the relationship between suction pressure, fluid temperature, vapor pressure and available NPSH must be carefully evaluated.

An excessive pressure drop at the pump inlet can cause the liquefied gas to partially vaporize, leading to flashing, cavitation and unstable pump performance. Pump location, storage tank pressure, liquid level and suction-line pressure losses therefore play an important role in LPG pump sizing and system design.

For demanding applications, sealless LPG pumps can provide an important containment advantage.

Conventional centrifugal pumps rely on a dynamic mechanical shaft seal between the pumped fluid and the surrounding environment. Because LPG is both volatile and flammable, leakage prevention is an important consideration when selecting pumping equipment.

A canned motor LPG pump eliminates the conventional dynamic shaft seal by integrating the pump and motor within a hermetically contained configuration. This reduces potential external leakage paths and eliminates mechanical-seal maintenance.

Depending on the project requirements, this type of sealless liquefied gas pump can therefore be considered for applications where fluid containment, reliability and reduced maintenance are important selection criteria.

LPG applications can nevertheless vary significantly according to the composition of the gas, storage conditions and process requirements. Propane, butane and mixed LPG streams do not have identical physical properties.

The pump must therefore be selected according to the actual fluid composition, operating temperature, suction and discharge pressure, flow rate, Total Dynamic Head (TDH), vapor pressure, available NPSH, materials compatibility and hazardous area requirements.

OPTIMEX evaluates these operating conditions to define an engineered pumping solution adapted to the requirements of LPG, refrigerated hydrocarbons and other volatile liquefied gas applications.

The development of the hydrogen economy is creating new requirements for equipment capable of handling hydrogen across production, liquefaction, storage, transportation and distribution infrastructure.

Where hydrogen is handled as a cryogenic liquid, liquid hydrogen pumps (LH2 pumps) may be required to transfer the fluid between different stages of the hydrogen value chain.

Potential cryogenic pumping applications can include:

• hydrogen liquefaction facilities,
• liquid hydrogen storage systems,
• LH2 tank filling and withdrawal,
• transfer between cryogenic hydrogen tanks,
• loading and unloading operations,
• liquid hydrogen distribution systems,
• industrial hydrogen facilities,
• specialized hydrogen research and test installations,

At approximately -423°F at atmospheric pressure, liquid hydrogen creates particularly demanding conditions for pumping equipment.

An LH2 pumping system must account for extreme low temperature, low fluid density and viscosity, heat input, vapor formation, available NPSH, materials behavior and hydrogen containment.

For hydrogen infrastructure developers, EPC contractors and equipment engineers, cryogenic pump selection must therefore be based on the complete operating envelope rather than flow and pressure requirements alone.

Sealless pump technology can be particularly relevant when evaluating equipment for hydrogen service because eliminating the dynamic shaft seal reduces potential external leakage paths.

However, any pump intended for liquid hydrogen service must be specifically engineered and validated for the required temperature, hydrogen properties, applicable standards and project-specific operating and safety requirements.

Industrial gas production facilities depend on cryogenic equipment for the production, storage and distribution of gases such as oxygen, nitrogen and argon.

In cryogenic Air Separation Units (ASUs) and associated industrial gas plants, pumps may be used to transfer liquefied products between process equipment, storage vessels and downstream distribution systems.

Typical applications can involve:

• liquid nitrogen (LN2) transfer,
• liquid oxygen (LOX) transfer,
• liquid argon (LAr) transfer,
• cryogenic liquid storage and withdrawal,
• transfer between production and storage systems,
• tank filling,
• circulation and process duties,
• downstream distribution and loading.

Industrial gas plants can operate continuously and often require equipment designed for high availability and predictable performance.

The selected industrial cryogenic pump must therefore provide the required hydraulic performance while accounting for low-temperature material behavior, vapor pressure, available NPSH, heat input and the characteristics of the specific liquefied gas.

For oxygen applications in particular, materials, cleanliness and equipment suitability must be specifically evaluated according to the requirements applicable to LOX and oxygen service.

The aerospace industry uses cryogenic liquids in research, component qualification, environmental simulation, propulsion development and specialized test programs.

Aerospace test facilities may require cryogenic pumping equipment to transfer or circulate low-temperature fluids between storage tanks, test stands, process systems and experimental equipment.

Depending on the program and facility, cryogenic fluids may include liquid nitrogen, liquid oxygen, liquid hydrogen or other specialized low-temperature fluids.

Potential applications for aerospace cryogenic pumps can include:

• cryogenic test stands,
• propulsion research and development,
• component and materials testing,
• environmental and thermal testing,
• cryogenic fluid storage and transfer,
• test equipment supply systems,
• research laboratories,
• specialized aerospace development facilities,

These applications can impose demanding requirements for operating temperature, transient conditions, repeatability, containment and system reliability.

Cryogenic pumps used in aerospace testing must therefore be engineered according to the actual test profile, fluid properties, hydraulic requirements and operating cycle of the facility.

For specialized R&D applications where standard industrial pumps cannot meet the required operating envelope, a custom-engineered cryogenic pump can provide a solution adapted to the test installation and project requirements.

The space industry represents one of the most technically demanding fields for cryogenic fluid handling.

Cryogenic propellants and fluids such as liquid oxygen (LOX) and liquid hydrogen (LH2) are used in certain rocket propulsion systems and require specialized infrastructure for storage, conditioning, transfer and testing.

Cryogenic pumping equipment may therefore be relevant to ground-based space infrastructure and development programs involving:

• cryogenic propellant storage,
• LOX storage and transfer,
• LH2 storage and transfer,
• cryogenic propellant loading systems,
• ground support equipment,
• propulsion test stands,
• rocket engine development facilities,
• research and qualification systems,
• other specialized cryogenic fluid handling installations,

For cryogenic propellant pumping, equipment may have to operate with extremely low-temperature fluids while meeting stringent requirements for material compatibility, fluid cleanliness, thermal management and containment.

LOX applications require particular attention to oxygen compatibility, while LH2 applications introduce the additional challenges associated with extremely low temperature, low density and hydrogen containment.

Sealless cryogenic pump technology can offer an important architectural advantage by eliminating the dynamic shaft seal, particularly for applications where minimizing potential fluid leakage is a key design objective.

Space-related cryogenic applications are nevertheless highly specialized. Pump configuration, materials, electrical design, hydraulic performance and qualification requirements must therefore be evaluated and validated individually for each project.