Safety Devices and Controls – Flashcards
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| Controls FLAME SUPERVISION |
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| Thermoelectric Flame rectification Vapour Pressure |
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| Controls FLOW |
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| Taper plug Valve Ball Valve Solenoid |
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| Controls IGNITION |
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| Permanent Pilot Electronic/electrical Hot Surface |
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| Controls PRSSURE |
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| Simple Regulator Modulating Regulator Air/Gas Ratio Control Valve |
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| Controls Safety |
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| TTB Interrupted thermocouple Vitiation Sensing Pressure Switch Hi-Limit stat |
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| Controls Temperature |
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| Liquid Expansion Thermostatic Switch Thermistors Bi metallic Switch Rod Type Wax Capsule |
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| FSDs that have a max operating time of 180seconds |
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| SPACE HEATER |
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| FSDs that have a max operating time of 45 seconds |
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| Storage water heater 35-70kW |
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| FSDs that have a max operating time of 50 seconds |
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| Storage Water Heater <35kW |
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| FSDs that have a max operating time of 60seconds |
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| Central Heating Boilers Cooker Ovens DFE W.A.U 60kW gross Combi/Multipoint WH |
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| FSDs that have a max operating time of 90seconds |
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| COOKER HOTPLATE |
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| Flame Supervision Devices Flame Rectification (Ionisation) |
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| Electronic method of FSD,very quick acting. Principle: Within a flame there are positively charged particles called IONS These can conduct an electrical current. But will only happen when a flame is present. |
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| Flame Supervision Devices Thermo-Electric |
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| Principle:Same as thermocouple. Small Electromagnet spring loaded Main Valve Interrupter Valve Thermocouple |
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| Flame Supervision Devices Thermo-Electric "CLICK TEST" |
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| 1.With MAIN BURNER operating 2.Isolate the gas supply at A.I.V 3.Check time taken for thermoelectric,magnetic valve to close. 4.After close of valve,Restore gas supply at A.I.V 5.Check there is no gas at the burner before relighting the appliance |
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| Flow Control Gas Taps |
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| Used to control throughput of gas fires n cookers Consist of taper plug held in position by compression spring. |
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| Flow Controls Ball Valves |
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| Commonly used for isolating appliances, and as ECVs. Maintainance free ,cannot be repaired |
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| Flow Controls Fire pedestal elbow |
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| Consists of Washer or O ring,attached to disc,which is then driven onto a seat by means of a screw thread or spring. |
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| Flow Controls Self sealing valves |
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| (Bayonet plug in sockets) Used in conjunction with flexible gas pipes for cookers. |
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| Flow Controls Solenoid Valves |
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| Electrically controlled gas valve,normally constructed so as to be normally closed. "copper wire on a bobbin" purpose is to turn on or off a gas supply by electrical means. |
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| Flow Controls Taper Plug Valves |
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| Normally consists of tapered brass or aluminium plug. Valve is operated manually by means of a handle |
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| Flow Controls Cooker Lid Safety Shut-Off Valve(SSOV) |
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| Unique to gas cookers with drop down lids. If the lid is dropped without the hotplate burners being turned off. This valve will extinguish the burners |
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| Flow Controls Self Sealing Disc on Seat Valve |
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| AKA Bayonet plug in sockets. Used with flexible gas pipes. For Cookers and tumble dryers |
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| How a Thermocouple works |
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| when two dissimilar metals are joined together at one end and heated a small electric current is generated. When tip of thermocouple is heated by a flame,(normally pilot),this generates small electric current,which is transmitted to control. |
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| Main Purpose of Controls into catagories |
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| Gas Pressure Regulation Flow Control Temperature Flame Supervision Multifunctional System Monitoring/safety |
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| Temperature Control Liquid Expansion Thermostatic Switch |
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| Positioned where the temp is to sensed. 1)spring loaded electrical contacts 2)When Contacts separate(due to liquid expansion)current flow stops 3)this switch controls gas flow by switching a solenoid gas valve on and off 4)found on trad CH boilers and combi boilers 5)PHIAL is located within the top of the heat exchanger |
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| Temperature Control Liquid Expansion Thermostatic Valve |
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| Principle:Liquid when heated expands Liquid contained in a PHIAL Flexible Metal Bellows Capillary Tube Most commonly found on gas cooker ovens |
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| Temperature Control Thermistor |
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| Do not contain any moving parts. Contain materials which when heated either decrease or increase in electrical resistance. This can be monitored by a PCB to activate an electrical solenoid to control flow of gas to a burner |
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| Temperature Control Thermo Disc |
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| Contained in a plastic housing,ativated by a bi-metallic disc. Disc will flex at predetermined temp Used on ch boilers,W.A.U and tumble dryers |
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| Temperature Control Thermostatic valves and switches |
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| Purpose is to automatically maintain or limit the temp of a given situation. eg air temp,water temp etc |
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| Which is the most common type of flame supervision device is fitted to domestic cooker ovens? |
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| Liquid Expansion |
