ABSA 4B EXAM QUIZ BANK | 1566 QUESTIONS | WITH ALL CORRECT SOLUTIONS.

ABSA 4B EXAM QUIZ BANK | 1566 QUESTIONS | WITH ALL CORRECT SOLUTIONS. Internal ____ is not required for dynamic type compressors. seals lubrication pressure monitoring corrosion monitoring temperature monitoring b Low pressure or high pressure are the two primary classifications of ____. centrifugal pumps sump pumps boilers draft fans pressure controllers e The boiler feedwater becomes increasingly ____ as it approaches the measurement of zero. acidic neutral softer basic alkaline a The following hydrocarbon(s) may be entrained in a natural gas stream: Propane Butane Ethane Methane All of the above e Although ____ is created, high viscosity oils are still preferred for low speed/high load systems. lower floc point oils lower oil friction high pour point oils high velocity oils higher oil friction e Every shift the boiler water should be ____. filled with dissolved solids tested condensed replaced evaporated b Sodium sulphite is a commonly used ____ in boilers. oxygen scavenger carbon dioxide scavenger coagulant pH inhibitor flocculant a Cement may be used for the protective coating of a ____. u-tube manometers orifice plates venturi tubes pressure gauges hot water storage tank e The hot exhaust gases from the gas turbine combustor travel downstream to be ____ in the turbine blading. expanded filtered heating contracted cooled a Recovery boilers must be shut down immediately when a tube leak develops because water generates a violent physical reaction upon contacting ____. white liquor black liquor green liquor molten smelt cooking liquor d In operating applications with high pressure and slow speed ____ are commonly used. coagulants light oils low viscosity mineral oils low viscosity synthetic oils heavy oils e During the power stroke of a four-stroke engine, the ___ is combusted. lubricating oil hydrogen air fuel/air mixture fuel d ____ are small relief valves that do not relieve pressure but are installed in systems to warn of impending overpressurization. Rupture discs Fusible plugs Turbine overspeed trips Sentinel valves Safety relief valves d The oil used in ____ must be able to dissipate the compressor heat and be easily separated from the refrigerant. refrigeration compressors reciprocating pumps air compressors steam turbines gas turbines a The antifriction bearing housing should have 2/3rd of empty space remaining after being topped up with ____. crude water lubrication mineral oil grease e Ammonia refrigerants have a high affinity for ____. non-condensable gases corrosion coagulants water flocculants d A ____ is a simple machine with two or more pulleys with a rope or cable threaded between them. hoist hacksaw block and tackle scaffolding portable grinder c ____ is one of the primary disadvantages of electric heating. Response time Increased corrosion Increased operating cost Decreased heat output Increased maintenance costs c ____ protocol should be used if the boiler will be exposed to subfreezing temperatures or will be shut down for an extended period or when there will be no foreseeable urgency to restart the boiler. Hot boiler lay-up Ready boiler lay-up Wet boiler lay-up Active boiler lay-up Dry boiler lay-up e A hammer is classified as a ____. recording device power tool hand tool measurement device calibration device c ____ is too toxic to be used as a refrigerant in building air conditioning systems. Water Freon Lithium Bromide Air Ammonia e The biological breakdown of bacteria in a closed vessel could produce ____. water air precipitation oxygen methane gases e Boiler feedwater is chemically treated to: Reduce foaming Reduce scale formation Minimize boiler metal corrosion Reduce carryover All of the above e A ____ is a simple machine used to lift or pull heavy loads with two or more pulleys with a rope or cable threaded between them. hoist hacksaw block and tackle portable grinder scaffolding c To prevent accumulation of oil deposits in ____ downstream equipment must be installed to filter and remove the oil from the air. four stroke engines reciprocating engines labyrinth seals compressed air systems two stroke engines d Thermostats may be categorized: The inherent design of the temperature sensing element The control action The temperature range Depending on the required application All of the above e Sour natural gas has unacceptable quantities of the following contaminant: Ethane Hydrogen sulphide (H2S) Mercaptan Propane Butane b Drift eliminators are installed in cooling towers to knock out entrained ____ in the outlet air stream. algae wood extractives floc coagulants moisture e ____ are designed into large air ducts to increase the inherent stiffness. Flanges Butt connections Circular sections Diagonal creases Thermocouples d If the cross-sectional area of an air duct is decreased the velocity of the air travelling through the air duct will ____. produce eddy-currents be increased remain constant be decreased experience a swirling effect b Cavitation in pumps is when the pressure in the suction line to the pump drops below the vapour pressure of the liquid. To reduce or eliminate the cavitation you would? Decrease the suction pressure Increase the suction pressure Purge the suction of the pump Increase the discharge pressure Decrease the discharge pressure b Freon-12 (R-12) is ____. corrosive on metals when contacts moisture non-toxic flammable explosive when mixed with air toxic b The design of the cone-shaped lip enables the ____ to pop open. PSV globe valve check valve butterfly valve non-return valve a A try cock is a piece of equipment installed on a boiler to measure the ____. pH flow rate pressure temperature water level e ____ is spent once it has absorbed airborne contaminants up to 20% its own weight. Membrane filters Mechanical filters Coagulant filters Electrostatic filters Activated carbon e Boundary lubrication can occur when: Metal to metal surface contact is present Limited lubricant supply Intermittent lubricant supply Equipment startup/shutdown All of the above e ____ is the temperature to which air must be cooled for water droplets begin to condense out of the air. Ventilation Dewpoint Humidification Frost Infiltration b The salt solution has reached ____, at the point where the ratio of water and salt no longer changes. cloud point floc point pour point equilibrium superheat d The ____ of a refrigeration lubricant is the temperature at which waxy particles solidify and separate out of the oil to give a cloudy appearance to the mixture. pour point viscosity grade floc point viscosity number viscosity index c Mineral salts can be removed from a humidifier by soaking it in a(n) ____. weak acidic solution distilled water water strong acidic solution weak base solution a The fixed blades of a ____ are also referred to as the stationary sections. impulse turbine reaction turbine internal combustion engine gas turbine heat recovery steam generator b One crankshaft revolution is required to produce one power stroke in a ____. reciprocating engine two-stroke engine gas turbine four-stroke engine steam turbine b Depending on the composition and operating conditions of the feed gas, ____ can be used to remove sulphur. Condensates Filters Ammonia Glycol Amines e Garter springs hold the ____ in the proper position in a steam turbine. condenser baffles carbon ring sealing glands steel billets refractory c When friction is experienced between two objects: The motion will be resisted Lubrication can be used to reduce the generation of heat Heat is generated Lubrication can be used to reduce motion resistance. All of the above e Dissolved oxygen is the primary cause of ____ in cooling towers. corrosion lubrication coagulation organic growths (slime) flocculation a In a unit ventilator, the ____ performs the heating or cooling heat transfer to the air. duct dehumidifier furnace evaporator coil component e Suspended matter describes any debris or ____ present in the cooling water. dissolved oxygen organic matter pH dissolved solids dissolved carbon dioxide b Carbon rings are installed on small steam turbines for ____. heating cooling attemperation