A pilot light is a small gas flame, usually natural gas or liquefied petroleum gas, which is kept alight in order to serve as an ignition source for a more powerful gas burner. This page is about the physical properties of gas as a state of matter A flame is often defined as the visible (light-emitting part of a Fire. Natural gas is a Gaseous Fossil fuel consisting primarily of Methane but including significant quantities of Ethane, Propane, Liquefied petroleum gas (also called LPG, GPL, LP Gas, or Autogas) is a mixture of Hydrocarbon Gases used as a Fuel
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Uses
Common applications include household water heaters, central heating systems, flame throwers, and hot air balloons. Water heating is a thermodynamic process using an energy source to heat Water above its initial Temperature. For the Grand Central Records albums see Central Heating (Grand Central album and Central Heating 2. A flamethrower is a mechanical device designed to project a long controllable stream of Fire. The hot air balloon is the oldest successful human-carrying Flight technology While most commercial kitchens still rely on pilot lights for burners, ovens, and grills, current residential systems typically use an electrical ignition.
Safety Protection
In natural gas furnaces, water heaters, and room heating systems, a safety cut-out is usually included such that if the pilot light goes out the gas supply to the pilot and heating system is shut off by an electrically operated valve. This cut-out usually detects the pilot light in one of three ways:
- Sometimes a mercury filled sensor is used to detect the heat of the pilot light. Expansion of the mercury results in sufficient pressure to operate an electrical switch that interrupts the flow of electricity and shuts off the gas valve when the pilot light goes out.
- Sometimes a photoresistor is used to detect the light from the pilot lamp. A photoresistor or Light Dependent Resistor or CdS Cell is a Resistor whose resistance decreases with increasing incident light intensity Electrical circuitry connected to the photo-cell provides a current sufficient to keep the gas valve open all the time the pilot light is still burning.
- Use of a pilot generator or a thermocouple in the flame provides heating appliance safety as it generates enough electrical current from the burning flame to hold the gas valve open. In Electrical engineering and industry thermocouples are a widely used type of temperature sensor and can also be used as a means to convert thermal Potential In Electrical engineering and industry thermocouples are a widely used type of temperature sensor and can also be used as a means to convert thermal Potential If the pilot light goes out, the pilot generator cools off and the current stops, closing the gas valve.
The above methods are examples of the use of "fail-safe" safety protection. Fail-safe or fail-secure describes a device or feature which in the event of failure, responds in a way that will cause no harm or at least a minimum of harm
Energy waste
In domestic heating systems with pilot lights it has been estimated that on average half the total energy usage is from the pilot light, each pilot light using from 240–500 W of gas (8–16 GJ/year). The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. The joule (written in lower case ˈdʒuːl or /ˈdʒaʊl/ (symbol J) is the SI unit of Energy measuring heat, Electricity [1] [2] [3] That said, the heat from a pilot light in many appliances (furnaces, space heaters, hot water heaters) is generally released in the same chamber as the primary burner. The heat energy provided by the pilot light in these types of devices provides a minimal amount of heat to the device; the gas burned is not "wasted", since it contributes to the purpose of the device.
Modern alternatives
An alternative to the pilot light is a system that provides a high voltage electrical arc or “spark” between two electrodes close to the gas flow from the burner that is to be lit. The term high voltage characterizes electrical circuits in which the voltage used is the cause of particular safety concerns and insulation requirements An electric arc is an Electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive An electrode is an Electrical conductor used to make contact with a nonmetallic part of a circuit (e Fail-safe design for such a system requires the burner flame to be detected by passing an electric current through the flame, which is “received” by a control box, whilst the flame is established there will be a flow of electrons through the flame so the control box keeps the appliance working, should the flame extinguish, the electron flow will be broken so causing the control box to shut down the appliance.
A red-hot surface can also be used to provide ignition. Such igniters are often made of silicon carbide, silicon nitride, or another material that is durable under prolonged exposure to extreme heat. Silicon carbide ( is a compound of Silicon and Carbon bonded together to form Ceramics but it also occurs in nature as the extremely rare mineral Silicon nitride (Si3N4 is a hard solid substance It is the main component in silicon nitride Ceramics which have relatively good shock resistance Hot-surface igniters are commonly used in cooking ovens and broilers. An oven is an enclosed compartment for Heating, Baking or Drying.
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