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58 TRG-TRC011-EN
notes
period five
Application Considerations
In general, ASHRAE Standard 15-1994, “Safety Code for Mechanical
Refrigeration,” does not apply to absorption water chillers due to Section 2.3,
which states:
This code does not apply where water is the primary refrigerant.
Section 8.13.6 of the Standard, however, does affect direct-fired absorption
chillers. It states:
No open flames that use combustion air from the machinery room
shall be installed where any refrigerant is used … Combustion
equipment shall not be installed in the same machinery room with
refrigerant-containing equipment except under one of the following
conditions:
(a) Combustion air is ducted from outside the machinery room and
sealed in such a manner as to prevent any refrigerant leakage from
entering the combustion chamber, or
(b) A refrigerant vapor detector is employed to automatically shut
down the combustion process in the event of refrigerant leakage.
When halocarbon refrigerants (such as HCFC-123, HCFC-22, HFC-134a, etc.) are
present during a combustion process, they can break down into products that
are both harmful to humans and corrosive to machinery. The intent of
Standard 15 is to avoid both of these hazards by preventing refrigerant
exposure to any combustion process. Thus, the use of an open-flame device,
such as a boiler or the burner of a direct-fired absorption chiller, in a machinery
room is strictly prohibited by this section unless one of the exceptions is
employed.
Exception (a) allows combustion air to be ducted to the open-flame device from
outside the machinery room in order to prevent air (and refrigerants) present in
the machinery room from entering the flame. Alternatively, exception (b) allows
▲
◆ Combustion air ducted from
outside the machinery room
◆ Refrigerant vapor detector to
shut down combustion
process in the event of a
refrigerant leak
Figure 66