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This is a typical example of ‘design-to-prevent
problems’, which is a basic responsibility of an
engineered design by a registered professional
engineer or technologist.
The reason behind these deem-to-satisfy rules is to
keep soil and wastewater separate in the horizontal
position and to prevent raw sewage discharge from
the lowest-situated fixtures such as the shower and
bath, and thereby prevent a health risk.
Backflow prevention
Backflow in a drainage system is also a serious
health threat — specifically, backflow from the
municipal sewage system.
In a normal house, plumbers provide a gully
between the house and the municipal sewage
connection to act as an overflow facility so that
when there is a blockage in the municipal sewer,
the sewage can push back and overflow from
the gully of the next nearest house. This is in
accordance with SANS10400-P deem-to-satisfy
rules. But this can create a serious health risk and
an unpleasant situation or ‘nuisance’, as described in
SANS10400-P: P2.
It is important that the design engineer of a laboratory
checks where any backflow may occur — evident
from where the separate horizontal wastewater
discharge pipe exit from the building, and then the
backflow overflow inside the building and out of the
showers or baths.
The horizontal collector pipes below the ground floor
of a laboratory shall be separate for soil fixtures and
separate for the wastewater fixtures, and if there is
a collector pipe outside of the building for soil and
waste combined, then an overflow facility is essential
— at least on the wastewater drain pipe outside
the building.
A gully is an unhygienic fixture. Most of the time, it is
extremely dirty and germ-ridden and should not be
used in a hospital.
October 2019 Volume 25 I Number 8
Follow manufacturer’s specifications
The emergency ambulance entrance of hospitals today
has to provide shower facilities, and the discharge
from that cannot go into the municipal drainage. When
you design a hospital, there is a document R158,
which is a manual for the design of hospitals. Even
then, when it comes to the plumbing, all it says is
that it must be designed by an experienced engineer.
But how does one know if a person is an experienced
engineer? One way is that the engineer has to be
registered with Ecsa, which has a Code of Conduct,
which states you cannot do work for which you are
not qualified. They are also now looking to register
engineers as to their area of specialisation.
“These requirements are not contained in regulations,
or to be found in a book – it comes from experience.”
“The plumber has nothing to do with the design of
a laboratory – that will be the architect. Thereafter,
the user of the facility will specify what has to go
into it in the line of furniture and equipment, and
the manufacturer’s requirements in terms of this
will in turn determine the plumbing needs. This all
determines what will, in effect, be normal plumbing.
He reads the manufacturer’s drawings and provides
the piping.
“For this reason, plumbers must never underestimate
the importance of the manufacturer,” says Brink. “If
you don’t do what the manufacturer says in terms of
installation and maintenance, there is no warranty,
and the installer or operator is the one responsible.
So, the plumber must just follow those specifications
– and the plumbing itself is actually very simple.
Trends in lab design and installation
Laboratory architects and engineers will often defer to
specialist plumbers or laboratory furniture installers in
their design, due to the degree of specialisation.
Neil Laridon, financial manager and head of sales at
E.C. Laridon, a business with more than 70 years’
experience in laboratory installations in which he is
the third generation to run it, says firms such as his
are heavily involved in the design of the plumbing
and furniture of laboratories, “as only a handful have
experience in this specialised field.”
One of the principles is that, in situations such as
horizontal branch pipes and horizontal discharge
pipes, the soil and wastewater pipes must be kept
separately. This is critical to prevent raw sewage from
discharging through a shower or bath in the event of
a blockage in a combined horizontal branch pipe or
collector horizontal discharge pipe inside a building
and, more specifically, inside a hospital.
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Laboratories are dangerous
environments and require
quick, easy-to-use, personal
cleaning facilities such as this
emergency shower.
There are also only about four major installation firms in
this niche (including E.C. Laridon, Labscheme Allchem
and LabFurn), and about three architects’ firms. Each
serve a specific geographical region, while offering a
similar range of products from different brands.
www.plumbingafrica.co.za