Is your lubricant fit to withstand the long-term challenges inherent with carbon dioxide (CO2) refrigeration system operation?
March 04, 2020
With any refrigeration system, proper oil selection is key to providing proper long-term compressor protection and to ensure this equipment runs at maximum efficiency. The harsh conditions within CO2 applications require the use of wax-free synthetic lubricants, and while several synthetic base oil solutions are available, each faces unique challenges relative to oil management.
Polyol ester (POE) base oil products are often the solution because they offer the advantage of superior miscibility with CO2, which provides simplistic oil return management. The major concern with POE-based lubricants is that they are highly hygroscopic, which means they seek to absorb moisture from their surroundings.
Water in any amount can be detrimental to a closed loop CO2 system as ice formation can damage valves and lead to system failure. Excessive water promotes additional risk of hydrolysis, a chemical reaction that breaks down the POE oil and leads to the formation of highly corrosive carbonic acid.
In a perfect scenario, a system would be free of all contaminants including moisture, but this simply isn’t realistic.
“While it’s important to minimize the amount of moisture that starts in your POE lubricant, the moment you open the lid to your oil, the POE lubricant begins absorbing moisture from the surrounding atmosphere,” said Paige Holder, Summit’s market manager for refrigeration lubricants. “Regardless of whether absorption of water occurs before, during or after installation, the lubricant must be designed to resist chemical reaction with the water it comes in contact with.”
Summit’s RPE-744 Series are fully synthetic POE lubricants specifically formulated to provide long-life solutions designed to withstand harsh conditions present within CO2 refrigerant applications. In addition to providing excellent wear protection, the RPE-744 Series offers superior chemical, thermal and hydrolytic stability to protect against product degradation in the presence of contaminants. Summit’s RPE-744 Series also provides superior corrosion protection to protect all metal surfaces from the harmful impact of acid corrosion.