Millwright period 3 compressors Correct 100%(RATED A+)

What are the 2 main categories of screw compressor - ANSWER Oil wet and oil free dry screw comp Witch rotor is the driver on a screw compressor - ANSWER The male rotor What determines the capacity of a screw compressor - ANSWER Rotor length, diameter, lobe flute design and speed What determines the discharge pressure of a screw compressor - ANSWER The location of the inlet port along the rotor, the length of path and the discharge port location What function does the oil in a wet screw compressor serve - ANSWER Remove heat, seal gaps to prevent leakage, lubricate and reduce noise What is the simplest type of control system in a screw compressor - ANSWER Online/offline control Which control system allows the compressor to produce only the amount of air required - ANSWER Modulation control What must be included to prevent rotor contact on a dry screw compressor - ANSWER Timing gears need to be used Where are the thrust bearings located on a screw compressor - ANSWER On the discharge side Air filter should be able to remove particles down to what size before air enters the compressor - ANSWER 5 microns What two functions do oil separators perform - ANSWER Oil separation from air, acts as an oil reservoir What two functions do the minimum pressure valve perform - ANSWER Maintain a minimum air pressure in separator, acts as a check valve preventing flow reversal What is the function of the thermal mixing valve - ANSWER To maintain a minimum oil injection temp What is the advantage of the helical lobe blower vs the 2 lobe blower - ANSWER Increases Pr and smother air delivery Only helical lobe blowers need timing gears - ANSWER False What should be done first before putting a compressor back into service after an overhaul or motor change - ANSWER Check for correct rotation after motor or air unit replacement Lobe blowers are used to produce high Pr and low volume - ANSWER False What should be done before resetting the timing on a lobe blower - ANSWER Determine whether the unit is unidirectional or bi directional rotation What should be done before starting a blower after an overhaul - ANSWER Turn it over by hand to ensure that it rotates freely in the direction of rotation Care should be taken to prevent what from happening while you are attempting to set the lobe clearences - ANSWER Take care to prevent pinch points and injury What type of compressor is flooded with oil all the time it's running - ANSWER Wet vain How do babe compressor systems often eliminate the need for a receiver - ANSWER By using an inlet throttling control system What is the only major moving part in a sliding vain compressor - ANSWER Rotor assembly What does it mean for a compressor to have a built in pressure ratio - ANSWER This pressure ratio is not adjustable as are reciprocating compressor What prevents the high Pr discharge air from leakage back into the low pressure suction area in vane compressor - ANSWER Centrifugal force along with an oil seal on the vain How is compressor capacity determined on a vain compressor - ANSWER By calculating the volume of air between the sets of vanes at max volume x by the number of vanes x the rom of motor Why do dry vain designs generally produce air at low presssures - ANSWER Can't handle the temps made by higher Prs required, have increased friction between the vanes and the stator What is the purpose of the oil in a wet vain compressor - ANSWER Cool, seal, lubricate, prevent corrosion and operate the servo valve.