The Sealing Characteristics of a Mechanical Seal for a Centrifugal Blood Pump

Abstract

A centrifugal blood pump has been developed as an implantable left ventricular assist device. A newly designed mechanical seal with a recirculating cooling water system is used for the shaft seal. The mechanical seal separate cooling water and blood in the sealing face. The objective of this study is to establish the measuring method of bidirectional leakage of the sealed fluid and the cooling-water through the sealing face, especially when blood is used as the sealed fluid. The leakage of the blood to the cooling-water side was measured by the atomic emission spectroscopy. The leakage of the cooling-water to the blood side was measured by using the atomic absorption spectroscopy, by using the standard addition method, by the correction of hemolysis caused by leakage of the cooling water. As the results of the experiments, the leakage rate of both the cooling water and the blood were below 0.4 [ml/6h]. Therefore, the mechanical seal performed acceptably well to support its use in the centrifugal blood pump.