NSK Europe, the European arm of Japanese bearing manufacturer NSK, has developed deep groove ball bearings that do not require external lubrication for use in submersible pumps handling cryogenic gases such as hydrogen and LNG.
NSK has developed special shaft bearings with a cage made from self-lubricating fluoroplastic for submersible pumps that handle cryogenic gases and liquids.
The stainless-steel bearings with a cage made of self-lubricating fluoroplastic are seeing increasing adoption in submersible pumps as a growing number of projects promote the use of hydrogen as an energy source. These projects often use special submersible pumps that can reliably pump gaseous and liquid media in continuous or intermittent operation at low temperatures down to around -200°C.
In such pumps, the double bearing of the pump shaft is a critical design element. Corrosion resistance is essential, and no lubricant can be used other than the media washing around the bearing. However, this places tough demands on the material pairing.
So NSK has developed a series of deep groove ball bearings specifically for these exceptional operating conditions, and several key design features provide differentiation from conventional pump bearings. For example, the inner and outer rings are made of a stainless steel adapted to the special requirements of rolling bearings.
A stable cage that occupies the entire inner volume of the bearing provides guidance for the rolling elements (also made of stainless steel), while the cage material, a self-lubricating fluoroplastic, ensures low friction running of the bearing without external lubrication. In addition, the high-performance fluoroplastic is extremely wear-resistant and offers good low-temperature properties at speeds up to 3600 rpm. The cage has a two-piece design, with the two halves joined by stainless steel rivets.
The NSK bearings are available in various sizes (shaft diameter 30–100 mm) and are designed for use in both larger hydrogen pumping facilities and decentralised applications, such as hydrogen filling stations.
