AS 2927:2019 pdf free.The storage and handling of liquefied chlorine gas.
7.8 Chlorine safety equipment
7.8.1 Leak detectors
7.8.1.1 Site requirements
Leak detectors shall be installed in chlorination rooms and where chlorine is connected for use in order to provide warning to personnel onsite as well as to manage impacts to neighbours.
7.8.1.2 Performance requirements
Leak detectors shall meet the following requirements and recommendations:
(a) If a chlorine leak is detected, leak detectors shall immediately activate the following:
(i) A local audible alarm system.
(ii) A local visual alarm (e.g. flashing red light).
(iii) (An) alarm(s) in a control room or an alert to a person responsible for operating or monitoring the installation (e.g. a duty operator receiving electronic notification, out of hours monitoring centre). The alarm shall be clearly identified as a chlorine alarm.
(iv) Automatic shut-off devices, if installed.
(v) Termination of mechanical ventilation, if installed and under continuous operation, unless it is an integral part of a scrubber system.
NOTE 1 Settings may depend on local regulatory requirements, although 1 ppm local alarm and 5 ppm shut down settings are common industry practice.
NOTE 2 A risk assessment may be undertaken to not include interlocking with ASDs if site factors demonstrate minimal off-site risk impact. Entries in Table 6.1 for ‘with ASDs” do not apply in this configuration.
(b) Leak detectors shall be installed and maintained in correct working order in accordance with the manufacturer’s specifications.
(c) Leak detector units shall be of a low maintenance design.
(d) Leak detector units shall be of a fail-safe design, so that any interruption to the internal circuit of the unit activates the alarm. The fail-safe operation shall react to —
(i) breaks in the electrical circuit; or
(ii) depletion or absence of electrolyte for the chemical cell, where applicable.
(e) A risk assessment shall be undertaken to identify the likely release points of chlorine and to determine the number and positioning of chlorine leak sensors. Sensors shall be positioned to avoid dead spots, mounted 300 mm to 500 mm above ground level and downwind of likely leakage points. They shall be positioned to allow for the vapour density characteristics of chlorine.
NOTE The system design and layout of an installation influences the number of sensors required.
(f) Leak detectors shall be capable of operating during a power failure of up to four hours duration (e.g. provided with battery backup, uninterruptable power supply) unless otherwise determined by a risk assessment.AS 2927 pdf download.