ABSA 5th Class | 250 Questions | With Completed Solutions.

ABSA 5th Class | 250 Questions | With Completed Solutions. Where are the return openings located regarding air distribution systems? Return air openings are located on inner walls. The minimum temperature of the water used in a hydrostatic test of a boiler cannot be less than what temperature? 20 degrees Celsius Which of the following are causes of pressure explosions? 1. effects of corrosion 2. weak pilot flame 3. stressed material due to heating too quickly 4. insufficient purge 5. scale and sludge build-up 1, 3, 5 Carbon, which is not combined with hydrogen, is referred to as: Fixed Carbon Maximum static pressure in a fuel oil line is approximately: 35 kPa Combustion of a fuel in a boiler furnace: should be performed with a minimum of excess air What is a hydrostatic test? A way in which pressure vessels can be tested for strength and leaks. How often do burner and fan motors which uses standard bearing normally require lubrication? Yearly On a hot water boiler, the pressure differential between the operating pressure and the safety relief valve set pressure must be (at a minimum): 1. 25% of operating pressure 2. 125% of operating pressure 3. 69 kPa 4. 25% of the safety relief valve set pressure 3, 4 In hot water boiler operation the maximum operating temperature should never exceed: 121 degrees celsius A substance, which will absorb humidity inside a boiler during dry lay up is: Activated alumina When draft is produced by natural means: cooler air surrounding the boiler increases draft Coal is composed of the following combustible components: Carbon, hydrogen, Sulphur Which of the following are causes of furnace explosions? 1. main fuel valve closed when the burner flame is lost 2. insufficient purge 3. burners lit from hot refractory 4. effects of corrosion 5. admission of fuel before ignition source 3,4,5 Which grade of oil is the most popular for domestic and small commercial boilers? Grade 2 The inclined manometer as compared to the U manometer is what? More accurate. How can the draft through a natural draft furnace be increased? Increase the temperature of the stack The main function of a gas burner is: provision of O2 - fuel contact The minimum distance from furnace to oil storage tank is: 2 feet One of the main component of an electric ignition system is the step-up transformer which takes 120 V and boosts it to _____ volts 10,000 - 12,000 volts. Combustion of a fuel in a boiler furnace should be performed in what conditions? There should be a minimum of excess air. What type of oil burner is used when oil is supplied under high pressure? Mechanical Atomizing Burner An air atomizing compressor is usually what type? A rotary type. Which of the following advantages does oil have over coal as a boiler fuel? 1. requires less storage space 2. costs less to handle 3. fuel quantity is easier to control 4. burns more cleanly All of the above In a boiler burner with 3 fixed capacity nozzles,the intermediate and high burner nozzles have higher capacities than the primary burner nozzle for what reason? To allow better boiler warm-ups What is a manometer used for? Measure draft A draft gauge on a furnace indicates the draft in: mm of water column A solenoid type fuel gas valve is held close by what? Fuel pressure Regarding a burner with 3 fixed capacity nozzles,the secondary and tertiary nozzles are ignited by: Primary burner Ethane is a component of natural gas and constitutes a percent volume of: 10-20% An interrupted pilot does what? Lights, completes a trial, and extinguishes after the main flame is established. A very popular packaged boiler gas burner is the: Ring burner An intermittent pilot does what? Lights the main flame and remains on with it. Before atomization can occur, heavy oils are heated to approximately _____ degrees C. 95 A fuel storage tank must be located a minimum of ____ away from the furnace 2 feet A refractory burner disadvantage is: High initial cost Maximum static pressure in a fuel oil line is approximately what? 35 KPA When a gas fired burner is burning fuel properly a) it will have a blue flame with short yellow tips b) the furnace will pulsate c) there will be no turbulence d) it will have a long bright yellow flame e) the induced draft fan can be shut off A In a forced draft system, the furnace pressure is: Above atmospheric pressure Copper and copper alloy piping and tubing is not used in power plants when: Temperature is a prime factor. Pipe is manufactured in two main categories, welded and a) threaded b) soldered c) brazed d) flanged e) seamless E Steam traps should be installed below the ________________ point in the system. lowest Expansion bends have the advantage over the expansion joint for one of the following reasons: There is little chance of leakage Expansion of piping is controlled by: 1. anchoring the pipe at both ends to prevent movement 2. installing a corrugated expansion joint in the line 3. installing an expansion bend in the line 4. anchoring the pipe at both ends and installing hangers every five metres 2,3 A disadvantage of using threads to join pipes and fittings is?: the effective wall thickness is reduced Pipes made of copper and copper alloys are used most often where? In plumbing applications. The two types of expansion joints are the ________________ and the slip expansion joint. Corrugated A purpose of a steam trap is to: automatically drain condensate from steam lines For varying wall thickness' of pipe, tables are developed which give the dimensions and: mass in kg/m Relative to valves, a frequent cause of serious accidents is due to: wrong materials of construction A valve which often contains a dashpot to cushion the action of the valve is the: lift check valve Before admitting any steam to a steam piping system it is imperative to first: positively ensure that no water or condensate exists in the piping Relative to pipes and fittings, an anchor chair is used to: support pipe A piping support device which allows axial movement of the pipe is the __________. adjustable roller stand Hot oil convection heaters have an approximate efficiency of: 75 - 85 percent Fire is a distinct possibility in hot oil systems because of the use of flammable products. For this reason the system must what? Be kept leek free.