RMO Practical Exam Questions and Complete Solutions.

RMO Practice Exam Questions and Complete Solutions in addition to evaporator pressure, what other force determines the flow through an automatic expansion valve - Answer: Spring Pressure what would best describe refrigerant in the last evaporator coil? - Answer: superheated vapor what is the auxiliary oil pump used for ? - Answer: starting up what is the steam jet on a surface condenser used for? - Answer: create proper exhaust vacuum what is used to track the speed of a steam turbine? - Answer: tachometer what is the reason to put two low side floats in parallel? - Answer: each one feeds its own evaporator how do you increase pressure of a centrifugal compressor? - Answer: increase the speed of the motor to raise 10 ILbs of water 1 degree, how many BTUs do you need? - Answer: 10 BTUs on the high side of the system, liquid stop valves should be placed.. - Answer: in front and after the sight glass a reciprocating compressor shaft seal is made up of.. - Answer: metal where do non Condensables and moisture collect - Answer: condenser when is the centrifugal water pump considered a "Lift Pump" ? - Answer: when the suction inlet of the water source is below the pump level if you are using a recovery machine to recover refrigerant from the system without using the system compressor, what kind of recovery machine is that? - Answer: Self Contained an open type compressor is keeping the refrigerant from escaping by tightening a seal made of .. - Answer: Carbon and metal if refrigeration oil is measured to have a viscosity and the viscosity number is low, what does that mean? - Answer: flow easily, smoothly if you need to add another pump online, how do you do it? - Answer: open suction side valve and put discharge valve in throttle position the automatic expansion valve is used instead of a TEV. it maintains a constant pressure on evaporator. another function it has is.. - Answer: on water type evaporators, freezing will not occur if 10 Btus is transferred to 10 LBs of water, increase in temperature is closest to.. - Answer: 1 degree F the unit used to measure the amount of electrons flowing past a certain point in an electrical circuit is called? - Answer: Ampere before using a voltmeter, the technician should always - Answer: set the range selector to a setting higher than the voltage expected to be read as an RMO, you enter a system of a reciprocating refrigeration unit. this system has a 150 LB. refrigerant charge. you would expect to find stop valves.. - Answer: on the inlet supply and discharge line regardless of the safety classification of the refrigerant in use, in the event of refrigerant to escape, the RMO should be aware of.. - Answer: Oxygen Deprivation when you are finished leak testing with nitrogen and R-22, the next step would be.. - Answer: vent refrigerant and nitrogen into open air the type of refrigerant in the feeler bulb on a system would b.. - Answer: non flammable / non toxic after the compressor, you have the oil separator, which.. - Answer: in general, returns the oil back to the crankcase what controls a solenoid valve on a motor? - Answer: Volts why is glycol a better brine than sodium chloride? - Answer: no corrosion what does a filter drier do ? - Answer: Removes particles, removes moisture and removes acid how does a reciprocating compressor vary capacity? - Answer: Cylinder Unloaders, Hot gas bypass, Motor Speed Variations a safety head is - Answer: valve plate being held down with a spring when water turns to ice, what takes place? - Answer: latent heat of fusion why do cascade systems use two compressors? - Answer: to negate the effect of high compression ratio what could happen if the spring of a TEV were to break? - Answer: Flood the evaporator how does a solenoid valve work? - Answer: open a plunger and let refrigerant in a water regulating valve is connected to the outlet of the condenser. what is the valve designed to do? - Answer: maintain a constant condenser pressure the outlet from a fan or air duct used to ventilate refrigerants must be at least ____ feet from any air intake or exhaust or any openings in an adjoining building. - Answer: 20 on a valve plate, where are the suction and discharge valves located? - Answer: Suction on bottom and Discharge on top what is superheated vapor? - Answer: vapor above its boiling point you are an RMO and you start the machine and the machine doesn't start. your fuses, circuit breakers, and electrical components are all good. what would you check next? - Answer: low pressure cutout, pressure switch due to a cold front, there was a sharp drop in outside most likely effect of this condition on the operation of the reciprocating machine would be that the thermostat causes solenoid valve to ? - Answer: close, and the compressor pumps down and shuts down on low pressor a jet ejector is used to raise oil mixed with refrigerant which has collected at the bottom of the evaporator. if restricted? - Answer: you will have insufficient head to lift the oil why should you charge with vapor? - Answer: you can freeze water in the tubes with liquid the most common metering device used today in a reciprocating commercial refrigerant system over 3 tons is? - Answer: thermostatic expansion valve an RMO observes a gauge that reads the saturation pressure of a refrigerant. if chilled water is being circulated as the cooling medium, the reading can best be used to estimate the... - Answer: temperature of the chilled water being pumped to the building spaces that are bing cooled multistage centrifugal compressor, each stage? - Answer: Tip speed is more with each stage if you were running three compressors which best describes the state of refrigerant leaving the third compressor? - Answer: highly superheated vapor what is the purpose of the equalizer line? - Answer: to make up for the pressure drop in evaporator if you are using a portable compressor recovery unit to remove vapor, what would happen when you are recovering ? - Answer: vapor density is decreased the amount of refrigerant that flows through the orifice plate is determined by : - Answer: difference in pressure between the high and low side unloaders are used too - Answer: reduce capacity a room temperature controls a solenoid valve in a liquid line. the compressor on/off is controlled by? - Answer: the low pressure control which of the following ashrae safety groups is most dangerous - Answer: B3 an operator has been assigned to run a centrifugal compressor. of the following actions a capacity control is most likely achieved is through? - Answer: adjustments of the impeller inlet guide pre-rotation vanes when charging a system with liquid refrigerant, with a set of manifold gauges, what positions are the valves on the manifold? - Answer: high side back seated, low side front seated according to the safety handbook, how much refrigerant can be recovered into a 60 LB container - Answer: 45LBs assume that the operator has a choice of 4 valves to select from and wants to minimize pressure drop. of the following the operator should not use? - Answer: Globe Valve which safety group does ammonia belong too? - Answer: Group 2, B2 during a walk through of the engine room the RMO notices excessive superheat at the evaporator outlet, this would most likely be caused by? - Answer: All Of the above (Starved Evaporator, Leak in the system, low refrigerant charge,) frost appearing on the suction line, and part of the compressor is caused by? - Answer: Flooded Evaporator a constant pressure expansion valve is being used instead of a TEV. under various loads, will - Answer: Starve The Evaporator you are an RMO assigned to the 3rd floor in an assembly room. attendance and temperature have increased during the afternoon, therefore a colder water supply is to be produced. in order to accomplish this you should? - Answer: lower the compressor suction operating pressure. what refrigerant systems are the most likely to leak refrigerant in building spaces that are being cooled? - Answer: direct systems upon being assigned to a facility during inspection of the facility, you find there has been failure to maintain water treatment. inspecting condenser water, the first evidence would would most likely be.. - Answer: increase in compressor head pressure during a particular round, an operator notices that the suction line and part of the compressor are frosted, the most likely cause of the condition is.. - Answer: Expansion valve too wide with respect to fire safety, ANSI/ASHRAE refrigerant safety classification that is most dangerous is? - Answer: A3 according to NYC fire code classification of refrigeration, ammonia would fall under which group? - Answer: Group 2 orifice plates may be used as a metering device component in a centrifugal system. the vessel which they are contained in can also serve as - Answer: Economizer a rupture disc in a centrifugal refrigeration machine is normally located on the - Answer: Evaporator when operating a refrigeration unit, the operator notices that the motor compressor is short cycling, the unit is using a low side float valve. this would indicate? - Answer: additional refrigerant to be charged when conducting a routine tour of plant operation, a RMO observes a significant increase in superheat temp. for the refrigeration fluid entering a reciprocating compressor.. of the following the most likely cause for this is? - Answer: Scale particles lodged in the TEV valve you are an RMO assigned to a facility where a refrigerant has been recently changed from a flammable refrigerant to R-22, at the moment you are planning to braze metal. on such making a repair in a machinery room, under circumstances you? - Answer: must ensure the flame is enclosed and vented to open air an operator has ben assigned to run a reciprocating compressor. the following action capacity control would most likely be achieved through? - Answer: opening the suction valve with some form of control an operator is using a sling psychrometer to measure dry and wet bulb temperature on a roof of a building where the cooling tower is located. if during the day the temperature remains constant, and wet bulb drops by 5 degrees F, and all the other conditions remained unchanged, the operator should see? - Answer: lower cooling water temperature being returned. if the eliminator plates located below the fan in an induced draft cooling tower have become clogged. of the following this would most likely result in ? - Answer: an increase in cooling tower water temperature bing returned which is not used as a cooling medium in an indirect system? - Answer: R-22 which refrigerant requires the approval for use by the NYC fire department? - Answer: Butane the cylinder unloaders on a reciprocating compressor is designed to ? - Answer: control cylinder clearance pockets efficiency of the refrigeration cycle is affected by the operation of the condenser. of the following, a more efficient operation of a centrifugal compressor results from? - Answer: lower the condenser pressure assume that the operator has a choice of 4 valves to select from and wants to minimize pressure drop. the operator should avoid the use of? - Answer: Globe Valve if 10 BTUs is transferred to 10 Lbs of water, the increase in temperature is closest to? - Answer: 1 degree F of the following, under what conditions of the heat in BTU/Min absorbed by the condenser water in a refrigeration plant is greater? - Answer: at high evaporator temperature and low condenser temperature refrigerants are characterized by the physical and chemical properties including latent heat, boiling point, refrigeration effect and others of the refrigerants in commercial industries used one with the highest latent heat and refrigeration effect is? - Answer: Ammonia