condition from a cold condition within a period of ten minutes. The trap
pressure differential shall be 1.72 kPa (1/4 psig).
2.9.7.3 Steam traps shall be readily available for ease of maintenance.
2.9.8 STEAM CONDENSATE PIPING
2.9.8.1 Condensate from all pieces of steam operated equipment shall be
designed to flow by gravity to return to main, flash tank, or condensate pump
set. This condition may require trenches in basement floors when pipe space
is not provided below basements. Domestic hot water heaters, heat exchangers,
and air heating coils shall be mounted high enough to allow gravity
condensate flow by gravity. Where sufficient room height is available,
provide a mezzanine or platform for easy access to equipment.
2.9.8.2 All condensate shall be returned to the boiler plant by a duplex
condensate pump set. Exceptions to this may be necessary when modifying an
existing system where a pumped return line to the boiler plant is not
available.
2.9.8.3 Use flash tank ahead of condensate pumps on condensate return system
from high and medium pressure steam traps. This is to reduce condensate
temperature to 91 degrees C (2oo degrees F) and to avoid flashing of hot
condensate. See VA Standard Detail 15705-26 for Flash Tank Piping.
2.9.9 VENT LINES
Provide an atmospheric vent line of sufficient size and extend it above the
roof of the building. Vents from condensate pump and flash tank shall connect
to this vent line. Safety valve shall be extended above the roof, to a height
of six feet, independent of the other vent line. To avoid long safety valve
discharge piping, safety valves may be located close to the terminal point if
there is no shut-off valve between the PRV and the safety valve.
2.10 VENTILATING SYSTEMS
2.10.1 GENERAL
Provide ventilation in the following areas where mechanical cooling may not
be but heating may be required: See ensuing Article.
(a) Electrical Equipment Rooms
(b) Elevator Machine Rooms
(c) Emergency Generator Rooms
(d) Gymnasiums
(e) Mechanical Equipment Rooms
(f) Motor Vehicle Maintenance/Storage
(g) Transformer Rooms
(h) Trash Collection Areas
(i) Warehouses
HVAC DESIGN MANUAL
2-24
HVAC SYSTEMS AND EQUIPMENT
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