In addition to routine editorial changes and rearrangements, the 1994 revision of the standard contains some significant changes from past versions, particularly Standard 15–78 which was in force for many years. One of the major revisions is in the occupancy standards as influenced by the refrigerant classifications adopted in the companion standard ANSI/ASHRAE Standard 34–92, which was discussed in Chapter 12. Along with the accommodation of the new refrigerant classifications, the standard specifies the types of building occupancies where the refrigerants of the various classifications can be applied. Furthermore, new ventilation requirements for machine rooms are specified, and these new specifications are reviewed later in Section 13.8.
ANSI/ASHRAE Standard 15–94 consists of 14 sections and three appendices. The first three sections cover preliminary explanations. Sections 4 through 7 combine the refrigerant classifications with indications of where and how each of these classifications can be applied. Sections 8 through 10 deal especially with vessels and their protection from high pressures. Section 11 is titled Installation Requirements and includes material on machine room ventilation that is especially important for ammonia. Appendices A and C address the new types of refrigerants—the blends of nonazeotropic mixtures. Appendix B is pertinent to industrial refrigeration systems, because it deals with emergency releases of refrigerants.