Turbomolecular pump are now widely used in plasma etching applications because of their cleanliness and ability to handle relatively high throughputs of gas continuously . standard pumps showed poor resistance to corrosion in initial trials and a lifetime of less than 50 hours of pumping chlorinated substances was quoted by one manufacturer . the primary point of attack is on the bearing via the lubricant , leading to failure . lubricating with PFPE fluid did not significantly improve the situation.