[jloughry]

From the excellent series of books What Went Wrong by Trevor Kletz:

...our first choice should be to see if we can remove the hazard—the inherently safer approach. For example, could we use a nonflammable solvent instead of a flammable one?...the second best choice is to control the hazard with protective equipment, preferably passive equipment, as it does not have to be switched on. As a last (but frequent) resort, we may have to depend on procedures. Thus, as a protection against fire, if we cannot use nonflammable materials, insulation (passive) is usually better than water spray turned on automatically (active), but that is usually better than water spray turned on by people (procedural). In some companies, however, the default action is to consider a change in procedures first, sometimes because it is cheaper but more often because it has become a custom and practice carried on unthinkingly. [1]

[1] Trevor Kletz. Still Going Wrong!: Case Histories of Process Plant Disasters and How They Could Have Been Avoided. Burlington, Massachusetts: Gulf Professional Publishing, 2003. ISBN 978-0750677097, page. 208.