Projects
to ensure that the airflow in the rooms are always correctly
balanced, with or without cupboards operational. In addition,
safety features such as no-flow warnings and run statuses
are indicated on purpose-made indicators in the user space.
All of the above systems are located in one single plant room
in order to be effectively screened. A seemingly complex
but carefully planned plant room space separates intake and
exhaust air, whilst ensuring required maintenance access,
coordination and identification of all seven subsystems.
The Civil Engineering concrete laboratories are served
by various internal subsystems and a dedicated fresh air
unit located in an external screened plant room. The large
multi-volume open plan heavy machinery laboratory
is ventilated with tempered and pre-conditioned fresh
air only to minimise energy usage, with air supplied via
long-throw jet nozzles to increase air velocity at ground
level and hence improve occupant thermal comfort in this
semi-industrial environment. Various enclosed laboratories
are air conditioned using exposed chilled water fan coil
units and ventilated as per room requirements. PVC ducting
and spark-proof ventilation systems are utilised where
chemical corrosivity and explosive risks are applicable. The
materials handling area where raw materials are loaded
and distributed is separated from the main laboratory and
inversely ventilated with fresh air supply from a high level
and extraction at low level. This ensures that the space is not
only always under negative pressure and properly ventilated,
but that the heavier-than-air dust particles are captured
effectively at low level.
A sample preparation room is used to cut and prepare
concrete samples, resulting in high dust loading of fine
particles. This space is ventilated by means of various canopies
Multiple fan arrangements in SANRAL plant room.
and strip curtain combinations to effectively capture concrete
dust at the source, extracting it via high-velocity ducting
to an external industrial baghouse filtration system. The
system ensures high efficiency filtration, capturing extracted
concrete dust in a series of cartridges and baghouse hoppers
automatically pulsed clean via a compressed air nozzle
Top view of
chiller plant
and screened
SANRAL plant
room.
www.hvacronline.co.za RACA Journal I August 2020 33