b'W RENCH W B Y B RUCE G ROSSMANPAGE 38 / NATIONAL CLOTHESLINE / OCTOBER, 2019ORKSWhats inside the air compressor?ast month I discussed the tank)thatpermitstheairto tor when the desired air pres-L basic components of a re- flow into the receiver but pre- sure is reached. AIR COMPRESSOR COMPONENTSciprocating compressorvents the air from flowing back Anelectricalairpressuremotor,pumpandreceiver out. control switch (see item #5) is(tank)which youll find onThere is a pressure relief generally used to accomplish RECEIVER OR TANKPUMP MOTOR RELIEF VALVE 8every machine in this family of valve (see item #2) guarding this. This switch opens an elec- 1 RECEIVER OR IN TANK (NOT VISIBLE)compressor. againstexcessivepressure trical circuit either controlling CHECK VALVEThismonthIwillexplain building up inside the cylin- a motor starter (see item #9)the function of other compo- der. When the pressure setting on larger compressors, or di- TANK ORnents which, when combined, of this valve is exceeded, this rectly opening the power cir- RECEIVERmake up a complete air com- safety device opens venting to cuit to the motor on smaller HEAD PRESSURE PRESSUREUNLOADER PORT 7 GAGEpressor. the atmosphere, thereby reliev- compressors. (NOT USED ON THISCOMPRESSOR)9 MOTORContaminants accumulate in the tankHEAD PRESSURE STARTERRELIEF VALVE2and must be removed through a drain RECEIVER 5 AIR PRESSURECONTROL SWITCHvalve at the bottom of the tank.ORTANK3 COMPRESSED AIRIn review, the electric motor ing excessive pressure insideWhen the air pressure in OUTLET VALVEis connected to the pump using the cylinder. the tank has reached the set- 6 HEAD PRESSUREbelts. The rotary motion of theA valve provides a means tingonthepressurecontrol 4 UNLOADER VALVEmotor turns a flywheel on the of shutting off the air flow out switch, shutting off the motor, AUTO DRAINpump linked to a crankshaft ofthecompressor(seeitem pressurized air is trapped be- VALVE 6Awhich moves piston(s) inside #3). Ball valves serve nicely for tween the top of the cylinder ANOTHER TYPE OF HEADthepumpcylinderup,com- this purpose. and the tank check valve. PRESSURE UNLOADER VALVEpressing air and down suckingContaminants in the form When the air pressure in the (NOT USED ON THISair into the cylinder to be com- of small amounts of oil as well tankdropsandthemotor COMPRESSOR)pressed during the next com- aswateraccumulateinthe restarts,thispressurizedair loader valve (see item #6a) soTo safely control the mo-pression cycle. tankandmustberemoved. would resist the piston from therewillbenofurtherin- tor switching on and off, a mo-The compressed air leaves Thisisaccomplishedbya movingupinsidethepump crease in tank pressure tor starter is used (see item #9).the cylinder through the top drain valve located at the bot- cylinder, thereby placing an ex-Located near the air pres- Thetermmotorstarterportion called the head and is tom of the tank which, when tremely high load on the motor sure control switch is a gage means that there is a magneticpushedintoalargevessel opened,providesapathfor while it is starting. that indicates the pressure in- motorcontactor(switch)called a receiver or tank.pressurizedairtoblowcon- Topreventthis,asmall side the tank (see item #7).which does the actual switch-In order to familiarize your- taminants out of the tank (see valve called an unloader (seeTo protect the tank from ingofthemotoraswellasself with air compressors, de- item #4.) item #6) is used to bleed off excessive pressurization, a re- some form of motor overloadscriptionsoftheindividual Ihighlyrecommendin- this high-pressure air when the lief valve is used. These valves protection, usually in the formcomponent parts are as follow: stallinganautodraintype pressure control switch opens. aregenerallycalibratedto ofaresettablethermalover- Topreventtheairfrom valve to accomplish this, how- In some compressors, usually open at a preset pressure, ex- load device combined in onejust flowing back from the tank ever a ball valve will do nicely larger types, when the desired haustingtotheatmosphere, control.then into the cylinder when the if you remember to use it. pressure is reached the motor and should never be tampered Ifexcessivecurrentflowspiston moves down to suck inAs air pressure increases continues to run; however, the with and always be replaced through the motor, the circuitmore air, there is a check valve inside the tank there needs to cylinder head is unloaded to by valves having an identical automatically opens, shutting(see item #1 generally in the be a method to shut off the mo- the atmosphere using an un- pressure rating (see item #8). the motor off before damagecan occur. Thats it for this issue. Ill bebackinthenextissuewithmore good stuff on air com-pressorsandcompressedairWANT TO IMPROVEsystems.Bruce Grossman is the chief ofR&D for EZtimers Manufactur-ing, maker of the new EZ LevelYOUR PLANTSreturn tank water level control.Topreventboilerscalingandother damage, the EZ Level re-turn tank water level control re-PRODUCTIVITY? placesthattroublesomeballfloat valve in the condensate re-turn tank. 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