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Specialty lubricants designed for your DX ammonia refrigerant system

February 02, 2021

Adoption of direct expansion (DX) ammonia system designs have increased amid an ever-evolving environment of refrigerant-based regulations.  DX designs reduce the required refrigerant charge, which potentially reduces the impact of ammonia-specific regulations and harnesses the inherent benefits of ammonia as a highly efficient refrigerant.

The reduction of overall system components within DX system designs also offers opportunities for energy savings, but only if all the pieces and parts are optimized. Choosing the right refrigeration oil is key to maximizing energy savings in any system design, providing essential wear protection at the compressor and removing waste heat. 

Maximizing overall system efficiency also requires selecting a lubricant well-suited for the designed collection or return of any oil that carries over past the oil separator. Miscibility defines the ability for a refrigerant-lubricant combination to form a homogeneous mixture across an identified range of temperatures.  Traditional mineral oils, which are widely used in ammonia liquid overfeed systems, are immiscible with ammonia and require removal via draining from dedicated oil collection vessels. 

In the absence of sufficient drain points, immiscible lubricants can quickly foul DX evaporators and wreak havoc on operational efficiencies. 

Enter: Summit RPS Series refrigeration lubricants. A specially formulated polyalkylene glycol (PAG) synthetic ammonia compressor lubricant designed to function in ammonia refrigeration systems utilizing DX evaporators and rotary screw compressors.  Its optimum miscibility with ammonia is unique, allowing easier oil return to the compressor with no oil accumulation inside the system.  Advantages of RPS Series lubricants in your DX refrigerant system include:

  • Minimal oil carryover
  • Improve thermal efficiency and productivity gains
  • Reduce maintenance downtime

Contact Summit’s Refrigeration Compressor Market Manager Paige Holder ( or your Summit distributor today to make sure you’re getting the most out of your DX system.   

Please keep in mind, not all DX system designers provide PAG-based lubricants with initial design.  Please consult Summit’s technical team for guidance regarding product selection and change out procedure when replacing these products.


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NSF ISO 21469

ISO 21469 specifies hygiene requirements for the formulation, manufacture, use and handling of lubricants, which may come into contact with products during manufacturing or processing. The international standard applies to lubricants intended for use in food production, as well as cosmetic, pharmaceutical and animal feed industries. NSF ISO 21469 Certification by an independent, third party provides Summit with a means to obtain international acceptance for their products. 

You can see a list of Summit’s ISO 21469 certified products by clicking here.