Fixed gas detection equipment
Boiler Plant Room - Case Study
Customer A has a large Hospital Boiler Room and Plant Room complete with a CHP (Combined Heat & Power) unit - which is used to supply electricity generated by gas.
As this is a large and high Boiler Room containing five boilers and a CHP along with two compressors for the refrigeration plant it was decided that the best and most economical approach would be to use the S4S Guardian® Plus Addressable control panel and associated addressable sensors.
A flammable gas sensor is placed above the front of each boiler, one inside the CHP, one above the gas valve, one above the gas boosters and two ASU1 sample systems are used to draw samples from high levels within the boiler room to sensors mounted at 1.5m adjacent to the control panel.
Three Carbon Monoxide sensors are placed at a height of 1.5m from floor level between the boilers and one within the CHP to give adequate warning of any malfunctioning of the boiler / CHP combustion.
Two refrigerant sensors are placed below the compressors to monitor for toxic gas leaks.
Sounders and beacons have been fitted at each entrance to the boiler / plant room and two within the room.
On reaching first stage alarm (20%lel Flammable gas, 30ppm Carbon Monoxide, 100ppm Refrigerant gas) the sounders and beacons operate to warn personnel of the potential build up of dangerous gas.
In addition to this a signal is sent to BMS to warn of the situation.
On reaching second stage alarm (40%lel Flammable gas, 200ppm Carbon Monoxide) the gas valve operates to prevent any further gas entering the room and a signal is sent to BMS to warn of the situation.
On reaching second stage alarm (1000ppm refrigerant gas) the chiller unit compressors are shut down to prevent any further leakage and a signal is sent to BMS to warn of the situation.
Large industrial and commercial facilities often have dedicated boiler rooms that house boilers, water pumps, heating, ventilating and air conditioning (HVAC) equipment, and other mechanical equipment required to run a facility. The heated water or fluid used in boilers can be used in a variety of processes or heating applications, including central heating and local power generation. As boilers have been modernised to burn natural gas or a combination of fuels that are less expensive and more flexible than coal and oil, there are significant risks of leaks occurring in the gas plumbing and from the burners at the front of a boiler. Such combustible gas leaks create the hazardous condition of a potential explosion. An additional risk is the production and leakage of Carbon Monoxide (CO), an odourless, colourless and toxic gas that results from incomplete combustion, which occurs when there is not enough oxygen mixed with the fuel. All improperly ventilated or malfunctioning boilers have the potential to produce CO in varying concentrations. Consequently, the building facility manager must ensure that the boiler room is instrumented with a comprehensive gas detection, alarm, and mitigation system to protect the facility and its personnel. Hazardous gases found in boiler rooms and plant rooms include:
Combustible gases such as Methane and LPG Carbon Monoxide
Refrigerant gases (used in air conditioning).
Combustible gas leaks rapidly disperse throughout a boiler room, creating a hazard for any worker, who can act as an ignition source, by walking into the room. Fixed point combustible gas sensors are used to monitor boiler fronts and associated natural gas supply lines. The gas sensors are connected to a control panel that provides relays to enable activation of visual and audible alarms for warning conditions and for boiler shutdown at emergency levels. Typical set points are 20% lower explosion limit (LEL) for warning and 40% LEL for emergency.
In addition, toxic gas sensors are used to monitor for CO leaks in boiler rooms. If not detected, the build up of CO can pose a threat to any worker walking into the room. The sensors can be connected to the same control panel used for combustible gas, creating a complete hazard detection system.
Personal gas monitors are generally not appropriate for boiler room applications because they cannot detect build up of combustible and toxic gases in a non-occupied area.
Automation and Integration Strategies - Boiler rooms tend to not be accessed frequently, facility managers often need a remote monitoring solution as well. It is common for facility managers to connect the boilers to the central Building Management System (BMS) so they can monitor the functioning and efficiency of the boilers remotely. But it is also necessary to integrate the flammable fixed gas and toxic gas leak detector systems in the boiler room with the BMS so that the alarms can be displayed within the central facility management console and can be acted upon as part of a facility-wide control strategy.
Sensors for Safety Ltd can supply gas detection equipment for use in Boiler Rooms and Plant Rooms. Our low cost S4S Gaswarden system can be used for small to medium sized Boiler Rooms and Plant Rooms, whereas larger areas will require our S4S Guardian® Plus system which is capable of monitoring up to 640 detection points.