Introduction

Aside from leaks, which are discussed in Chapters 6 and 8, and outgassing, which is discussed in Chapter 6, other kinds of problem often afflict vacuum apparatus. For instance, vacuum pumps are frequently mechanical devices, and can suffer from the reliability difficulties that are common to machines in general. Contamination is often a concern in vacuum systems, and the pumps themselves are frequently sources of contaminants. These often take the form of pump oils and their vapors, and various types of particulate matter. Besides these general difficulties, there are numerous others that are peculiar to each particular type of pump.

Vacuum gauges are generally affected by contamination, and are often degraded by substances released from the pumps. The vibrations produced by some vacuum pumps can, in addition to increasing the likelihood of leak problems, also damage delicate structures inside certain vacuum gauges. (These points are also relevant for mass spectrometers, which are common items in vacuum equipment.)

These issues, and others pertaining to the use of vacuum equipment, are discussed in the following chapter.

Vacuum pump matters

Primary pumps

General issues concerning mechanical primary pumps

Perhaps the most serious problem pertaining to the use of mechanical vacuum pumps concerns, not difficulties with the pumps themselves, but those that they may cause to the rest of the system in the form of contamination – especially by pump oil.