// CODE SNIPPET
1107.0 Refrigeration Machinery Room Ventilation
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Refrigeration machinery rooms shall be provided with a source of outside air for ventilation and removal of rejected heat.
Refrigeration machinery rooms shall be provided with dedicated mechanical
exhaust systems. The exhaust systems shall have the
capacity to provide emergency purge of escaping refrigerant
at a rate of 30 air changes per hour (ACH) for ammonia, or for
other refrigerants as determined in accordance with Equation
1107.2:
(Equation 1107.2)
Where:
For SI units: 1 cubic foot per minute = 0.00047 m3/s, 1 pound = 0.453 kg
(Equation 1107.2)
| Q | = | Air flow rate, cubic feet per minute. |
| G | = | Refrigerant mass in largest system, pounds. |
Where a refrigerating system is
located outdoors more than 20 feet (6096 mm) from buildings
opening and is enclosed by a penthouse, lean-to, or other
open structure, natural or mechanical ventilation shall be
provided. The requirements for such natural ventilation shall
be in accordance with the following:
- The free-aperture cross section for the ventilation of a
machinery room shall be not less than as determined in
accordance with Equation 1107.3.
Where:
(Equation 1107.3)
F = The free opening area, square feet. G = The mass of refrigerant in the largest system, any part
of which is located in the machinery room, pounds.
For SI units: 1 cubic foot per minute = 0.00047 m3/s, 1 pound = 0.453 kg - The location of the gravity ventilation openings shall be based on the relative density of the refrigerant to air. [ASHRAE 15:5.11.5(a), (b)]
Exhaust inlets or permanent openings shall be located to provide ventilation
throughout the entire refrigeration machinery room.
Fans providing refrigeration machinery room
refrigerant exhaust in accordance with Section 1107.2 shall
be permitted to be automatically or manually controlled to
provide intermittent ventilation where the machinery room is
occupied or in accordance with Section 1107.10.
Fans required by Section 1107.2 to provide emergency
purge ventilation shall be activated by refrigerant Alarm 1 in accordance with Section 1106.4 and by a clearly identified switch of the break-glass type, or protected by an approved tamper resistant cover located immediately adjacent
to and outside of the principal refrigerant machinery
room entrance. Two colored and labeled indicator lamps
responding to the differential pressure across the purge fan or
current through the fan motor shall be provided for each
switch. One lamp shall indicate flow; the other shall indicate
no flow.
Exhaust from mechanical
ventilation systems shall comply with Section 502.2.2.
Fans and associated equipment intended to
operate the emergency purge of other than Group A1 or
Group B1 refrigerants shall be in accordance with the requirements
for a Class I, Division 1 hazardous location as specified
in the electrical code.
Makeup air intakes to replace the
exhaust air shall be provided to the refrigeration machinery
room directly from outside the building. Intakes shall be
located as required by other sections of the code and fitted
with backdraft dampers or other approved flow-control means
to prevent reverse flow. Distribution of makeup air shall be
arranged to provide thorough mixing within the refrigeration
machinery room to prevent short circuiting of the makeup air
directly to the exhaust.
Ventilation or mechanical
cooling systems shall be provided to maintain a temperature
of not more than 104°F (40°C) in the refrigerant machinery
room under design load and weather conditions.
Joints and refrigerant-containing parts of a refrigerating system located in an
air duct carrying conditioned air to and from an occupied
space shall be constructed to withstand a temperature of
700°F (371°C) without leakage into the airstream. [ASHRAE 15:8.8]
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