RACA Journal January 2020 | Page 37

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