Associations
continuous monitoring and integrated alarm system. The
principles are made of seven main components that certify a
homogenous working system. These are:
• Medical compressed air system;
• Alarm management system;
• Medical vacuum system;
• Distribution system;
• Area control units;
• Terminal units; and
• Medical gas supply – cylinder manifolds.
There’s a worldwide standard that outlines standards and
guidelines, ISO 7396-1. “The latest SANS 7396-1 standard is
currently under review and should be finalised in the coming
months. It’s still a young, developing industry. However, we do
have guidelines for state and private facilities,” he said.
The approach that the standards outline include:
• Three sources of supply: Each supply system shall contain
at least three independent sources of supply (except for
gases for driving surgical tools),
• Continuity of supply: The supply system shall be
designed to achieve continuity of system design flow and
pressure to the terminal units in normal and single fault
condition,
• Location of central supply systems: based on a risk analysis
the central plants for the medical gases may need to be
installed in separated rooms in different fire sections.
• Capacity and storage: Of any supply system shall be based
on the estimated flow profile, usage and frequency of
delivery.
• Quality of supply: Medical gases need to fulfil at least the
requirements from the respective Pharmacopeia (publication
of medicinal drugs).
• Identity of supply: Cross connections and commutations of
medical gases must be avoided.
“In essence, the design of a central supply system must
have three sources with double redundancy which provide
continuity of supply even if one source is down for routine
maintenance at the event of a failure of another supply
source,” Marks emphasised. The installation and maintenance
process requires the system to be tested to ensure it works
well. Marks mentioned that there are bodies, like the South
African Qualification & Certification Committee (SAQCC), that
assists in certifying and listing authorised gas practitioners to
install the system.
After him came Sagaran Chetty, marketing manager for
Gas Detection and segment manager for Oil, Gas and Chemical
Segments. He shared the fundamentals of fixed gas detection,
www.hvacronline.co.za
Sagaran Chetty from Draeger.
this focused on the history of gas detection, the various types
of sensor technologies, gas detection transmitters and the
specifications that are required to select the correct option. “The
system design is meant to detect if there is a risk, alarm and
notify of the risk and protect by means of activating emergency
measures in place,” he said.
There are in excess of 30 electrochemical sensors that
are capable of measuring more than 120 toxic gas variants,
infrared technology can measure a vast library of explosive
gases while catalytic bead technology will detect for both
explosive gases as well as hydrogen. He highlighted the
importance of having gas detection, stating that the correct
installation of gas sensors for the gas detection system is
extremely important. When installing detectors indoors
various factors need to be considered such as gas density, heat
from process or application, extraction points for ventilation
which will influence or manipulate the gas properties.
Dense gas requires the detector to be placed at a lower
height since they are heavier than air, while lighter gases
would require the detectors to be placed at increased heights.
Furthermore, installation of gas detectors outdoors should
be located downstream of prevailing winds, in addition to
considering the effects caused by obstructions by buildings,
tanks and other similar impediments. Areas where wind direction
fluctuates over season changes will also need to be considered. If
adequate precaution is not taken during the installation process,
environmental conditions may have a detrimental impact on the
efficiency of the gas detection system. Gas detection devices
require calibration at specified intervals, to ensure that the units
are operating optimally; these intervals are reliant on application
requirement, gas type, sensor technology as well as scheduled
maintenance.
Attendees received 0.1 CPD points and enjoyed light snacks
afterwards. RACA
RACA Journal I January 2020
35