(a) When mechanical refrigeration systems are specified,
designers shall include specification of a cycling feature for all
systems under 3.7 kW (5 horsepower (hp), to minimize the possibility of
icing and moisture carry-over. Designers shall evaluate whether
anticipated flow conditions will require the cycling feature for systems
3.7 kW (5 hp) and over.
(b) When desiccant systems are specified, designers shall
consult the Using Agency on dryness limitations.
Desiccant dryers are
capable of drying the air to a dewpoint as low as 40 degrees C (-40
degrees F), which may be considered too low for some medical or dental
applications. When required by the User, the design shall include
specification of equipment accessories that will permit upward adjustment
of air moisture to the required dewpoint.
(c) The relative advantages and disadvantages of mechanical
refrigeration dryers and desiccant dryers generate questions. Good
arguments may be made for in favor of either dryer type. Both systems can
be successfully utilized in MTF's if project-specific conditions and User
needs are taken into account and the equipment is properly specified.
Additional general information of this topic is provided in Annex A at
the end of this Section.
MCA Demand. System demand shall be calculated utilizing the
peak flow and simultaneous use data in Table 9-5, as a minimum. The
simultaneous use factors shall be used with judgement and modified to
adapt to special conditions if required.