Associations
Continued from page 35
He gave a brief overview on design specifications as
stipulated in EN12101, “because there’s no roof to put 3%
ventilation in and it can’t go in a wall either. The maximum
area is 2 600m 2 per zone in a basement because we’ve got
powered ventilation. The longest distance you can have in
your reservoir is 60m. It has to be divided with barriers and
dedicated extraction points in each and every smoke zone.
The smoke will need to be kept 2.5m above the floor,” he
shared. Anything below the specified threshold doesn’t
comply with the South African building regulations.
He looked at a getting smoke out of a basement
measuring 40 000m². “To get smoke out, we’d need 16 smoke
zones – if we divided using the smoke regulations. Inside the
basement, the smoke is isolated, and to get it out, a duct
needs to be put in the smoke zones to pick the smoke up
and take it out of the building. On average the smoke will
be at 221⁰C, so a Class H motor can’t be used because the
motor is 40⁰C above ambient which means if the basement is
between 20 – 30⁰C, it’ll only work until 70.” He recommends
putting in two large fans that will extract the air comfortably.
Electrical interlocks should be in the control panels. He further
mentioned having ducting, certified smoke curtains hanging
at 2.4m, and sensors installed throughout the basement to
ensure measurement of CO 2 . “You do need six air changes per
hour to purge CO 2 in a basement,” he says.
www.hvacronline.co.za
Burns went on to mention some code violations where the
industry is falling short. “The duct work we supply isn’t certified
to the Code. Fire dampers aren’t certified, electrical cabling is
installed upside down in the hottest place, the soffit. There are
shortcuts in installing the electrical cabling.” Code EN50200
states how electrical cabling should be installed, from how it
should be suspended so it can’t fall, etc. “We have to be careful
what we do,” he said.
He also looked at smoke clearance, the fans on display
provided a visual on the kind of size required to correctly extract
smoke. “Getting smoke out of a building is like herding sheep.
You have to take all the smoke and push it to a corner of the
basement and then depressurise at the corner of the basement.
When you have smoke clearance, you switch the fans off when
there’s a fire as they’ll operate like an eggbeater.”
“We have to stop saving our clients’ money, and start saving
lives. Because it is a waste to have all your equipment lying on
the floor 10 minutes into the fire,” he said.
After his presentation, the question and answer session
revealed some of the frustrations that engineers and contractors
face on site, some mentioning that there isn’t a match to theory
and practice, causing frustrations to qualified technicians. Others
confirmed the shortfalls, sharing that if one can’t design for fire,
they shouldn’t. It is a specialist engineering field.
AMS, a manufacturer and supplier in South Africa of fans and
acoustic products for heating, ventilation and air-conditioning,
sponsored the presentation and brought some of their globally
certified fans to the venue. RACA
RACA Journal I April 2020
37