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One of the more challenging applications to which we have successfully applied our products is for pumping liquid carbon dioxide (CO₂). Being a liquefied gas, it must be transferred at a controlled combination of low temperature and high pressure to minimise vapour formation, whilst its inherent compressibility and low lubricity places special demands on pump design.

The applications for CO₂ are many and varied, encompassing nuclear power generation, recirculation in commercial refrigeration plant, use as a blowing agent in foam-making processes and the extraction of essential oils from plant materials. All these applications require a pump that is able to cope with high pressure at the pump inlet, poor lubricity and low temperatures. All of these factors require a high integrity pump design and special attention to correct installation.

Other pump types such as rotary positive displacement pumps struggle with liquid CO₂ whereas our triplex positive displacement plunger pumps are able to provide a robust solution. At Cat Pumps, we have developed models and variants that specifically address the many applications for CO₂, with fluid heads manufactured from stainless steel for liquid and process compatibility, strength and thermal stability.  Their concentric, high density polished ceramic plungers are abrasion resistant, providing excellent seal life and the specially-selected plunger seals are lubricated by the liquid CO₂, so there is no requirement for additional seal flushing liquids.

In order to ensure that operators obtain optimum performance and working life from their pump seals, Cat Pumps’ CO₂ pump installations can also incorporate a seal condition monitoring system. This allows the user to constantly check the performance of the plunger seals so that maintenance periods and seal replacement intervals can be predicted.

A number of Cat Pumps model 6861 pumps have recently been installed in the nuclear power industry where CO₂ is the primary temperature control medium for advanced gas cooled nuclear reactors during the reaction process. The CO₂ used to top up the reactors and refuelling plant is stored in high pressure tanks and our pumps are being used to replenish these from the lower pressure bulk tanks that receive supplies from road tankers.

We know that users of CO₂ expect a pump that will give long working life and high of levels sealing integrity at all times and we can offer PD pumps suitable for a wide range of flows and pressures in a variety of industries and applications, incorporating additional features to minimise potential problems with icing.