7.3 Communications and alarms The number and type of alarms will depend on a number of variables, and a review of the design and risk assessments must be undertaken to validate this decision. Boiler systems shall be designed such that boilers will always remain in a safe condition and will shut themselves down upon critical alarm, without manual intervention. A lock-out condition requires that the boiler be attended and can only be reset locally. Some typical alarms are indicated in the three arrangements in Appendix 3. Risk assessment is likely to indicate that there is benefit in also relaying alarms and providing an emergency shut-down facility at a remote location e.g. for boilers that are left unattended for a defined period of time. Where the risk assessment shows that the existing alarms are inadequate for the proposed operation, new alarms will be required in order that boiler operators can take appropriate action. The following should be considered: x The response time for personnel to investigate and rectify alarm conditions shall be considered as part of the design of the control system; where a competent boiler operator is unable to attend the boiler within a reasonable time, a remote shut-down and lockout facility shall be provided; x Alarms shall be clearly audible and visible at a permanently manned location where persons who are trained to take the appropriate action can hear or see them; x It shall be possible to ascertain the current status of the boiler from the remote location; this may be as simple as a green light to indicate a no-fault condition or as complex as full boiler telemetry. The level of information required at the remote location shall reflect the level of knowledge of individuals at that remote location; e.g. it is unlikely to be appropriate to provide full boiler telemetry in a gate-house or reception area while more detailed information could be of use to those in, say, an e ngineer’s office; x The integrity and testing of communication links between the boiler house and remote locations, and the action to be taken by the automated system on the loss of that communication shall be considered as part of the design of the control system. An “auto - dialler” is not considered a robust means of monitoring a boiler unless it is capable of checking the integrity of the communications system, or taking action in the event of a loss of communication, or incorporates a means of remotely determining the boiler status and remotely shutting it down. 7.4 Gas detection, fire detection and automatic fuel shut-off systems Automatic fire detection and fuel shut-off is mandatory for all oil-fired plant. Burners shall include automatic shut-off valves on all fuel trains, and the control system shall close these valves when a fuel is not in use, and in the event of a fault condition. Dual or multi fuel systems shall include interlocks to prevent simultaneous use if the burner or boiler is not designed for this. The need for gas detection and automatic fuel shut-off systems will be determined during the risk assessment; generally speaking, modern boiler houses are regularly attended and well- ventilated spaces, making it unlikely that an accidental release of natural gas of sufficient volume to create a flammable atmosphere will develop. Further information is available from IGEM/UP/16 and IGEM/SR/25. Gas detection systems will be necessary where forced inlet and/or extract ventilation systems are employed, and where the gas is not sufficiently odorised (e.g. producer gas, or bio-gas) as leaks are likely to go unnoticed by boiler attendants. Similarly it may be necessary to consider CO and H 2 S detection in certain circumstances (e.g. where CHP engine exhaust ducting passes through a boiler house).
BG01 Guidance on the safe Operation of Steam Boilers Edition 2 – © 2019
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