Effect of surface roughness of mechanical seals under blood sealing

Abstract

A miniature mechanical seal with cooling water circulating system has been developed as a shaft seal for rotary blood pumps. The present paper describes the establishment of the experimental methods under blood sealing and the estimation of the effect of the surface roughness on the shaft seal problems, especially in the increase of the friction and the leakage. Micro-leakage rates of the blood and the cooling water were measured by an ion chromatography. In this method, the ion concentration was converted into the leakage rate. The frictional loss torque was measured by a torque meter. Results are provided with three types of surface roughness, Ra = 0.009 μm, Ra = 0.088 μm and Ra = 0.170 μm. It is shown that as the surface roughness increases the leakage decreases while the frictional loss torque increases under blood sealing. The best surface roughness in the torque and the leakage characteristics were different.

Influence of Surface Texture on Friction Properties of Mechanical Seals for Blood -Design Concept of Sealing Surface of Mechanical Seal for Ventricular Assist Device-

“…Load was applied by adjusting the distance between a pair of magnets, one connected to a servo-controlled actuator and the other behind the seal ring. The load could be controlled from 0.5 to 20 N in steps of 0.5 N. The frictional force F and friction coefficient μ were calculated using the following equations [17]:…”

Appearance of Hysteresis Phenomena on Hydrodynamic Lubrication in a Seal-Type Thrust Bearing with Dimples

“…Applying dimples and/or grooves to the lubricating area is an effective method for improving lubrication performance [1]. Consequently, this technology is being used in various mechanical elements such as bearings [2][3][4][5], seals [6][7][8], and piston rings [9,10].…”

Effects of Hematocrit of the Sealed Blood on the Leakage Characteristics of Blood Cell Component and Plasma Component in a Mechanical Seal

“…As a result, the mechanical wear of the sealing faces was less than 0.05 μm a day so that the durability for the long-term support more than 10 years of the device was revealed [2]. Tomioka et al [3,4] also examined experimentally that the lubrication characteristics of the mechanical seal with the Cool-Seal system and that the effects of the surface roughness of the sealing faces on the lubrication characteristics of the mechanical seal under blood sealing. They obtained the blood leakage by measuring the increase in the sodium ion concentration in the C. W. because the sodium ion is mostly contained in blood.…”