Are you preparing for MEO class 4 exams? But, not getting enough study materials to start your preparation? Nothing to worry about, in this article I will share a complete set of MEO Class 4 Oral exam questions asked on Function 4B i.e, MEOL.

The full form of MEOL is Marine Engineering at Operational Level. We normally refer to it as Motor. That covers the theoretical part of all machinery in the Engine Room. But, You’ll get a majority of questions on the machinery for which you’re going to be responsible after becoming  4E.

Function 4 MEOL includes but not limited to questions on

• Main Engine
• Aux Engine
• Boilers
• Purifiers
• Refrigeration and AC
• Pumps and pumping systems
• Compressors and Air system
• Steering gear and Hydraulic system
• Fresh Water Generator, etc.

To make it easier for you, I have divided the entire function into various sections. So this will help you prepare for MEO Class 4 Oral exams easily.

Related Read: You can practice/download MEO Class 4 Written Questions & Answers from here.

Let’s get started…

Function 4B MEOL: Main Engine and Related System

1. During maneuvering, how will you know leakage in Air starting valve?
2. T/C surging. Procedure to follow during the departure of the main engine?
3. Purpose of the negative cam in the distributor?
4. Fuel injector leaking? What does it indicate? Exhaust temperature will be high or low.
5. What all will check when you take a round of the main engine only?
6. Why turbocharger?
7. Surging and reasons for it
8. How the main engine reversing takes place?
9. There is an alarm of OMD. What actions will you take?
10. How the main engine reversing takes place?
11. What is the main difference between LO oil used in the crankcase for 2S & 4S
12. When you are taking indicator card and engine tripped on some mechanical trip what will be
    maximum pressure?
13. Stresses acting on 4stroke conrod. Are they any different than 2s conrod stresses?
14. Different means of reversing. How reversing took place in ur ship?
15. Draw indicator diagram for leaking fuel injector.
16. How is the firing order for the Main engine decided? Why 1-7-2-4-6-3-5 and not 1-2-3-4-5-6-7?
17. Importance of flywheel.
18. Stern tube lubrication
19. Piston rings, Determine Condition of piston ring w/o removing piston out.
20. Coolers on ME / AE
21. Critical Speed
22. Why chokes are used in engines, types of chokes?
23. Starting Air Line Safeties
24. Advance technology in Engines?
25. Types of the crankshaft. The welded crankshaft is welded where? AE has which crankshaft?
26. How do you measure the ovality of the big end? Why do you measure at those points only?
27. Why bottom end serrated?
28. BSFOC calculation (from qty of FO in liters )
29. Exhaust manifold- How pulse of exhaust gets converted into constant pressure?
30. The hydraulic exhaust valve and spring-loaded old type valves – what are the advantages?
31. Air cooler maintenance
32. Starting airline safeties
33. M/E fuel injector diagram operation.
34. M/E interlocks.
35. M/E Manoeuvring
36. M/E – What S denotes in SMC
37. What if the stroke to bore ratio less.
38. Advantages of super-long stroke.
39. M/E valve timing diagram.
40. M/E exhaust v/v how it operates. The function of sealing air. What if sealing air not present
41. Why exhaust valve doesn’t fall in the liner when spring air not present.
42. M/E bottom end bearing clearance procedure.
43. Cross head-why is it there in 2-s and what does it do primarily.
44. 2-s /4-s difference and difference between their lubrication system
45. Difference between c-case oil and cylinder oil, the oil used for camshaft lubrication. , cold corrosion.
46. Piston cooling in 2/s & 4/s, and parameters.
47. Jacket cooling Parameters.
48. Cylinder Lubrication in 2/s & 4/s.
49. Scavenge fire.
50. Explain crank case explosion.
51. Piston oil cooling line in both aux and main.
52. Safety valve on ME.
53. Prepare the main engine.
54. Cylinder line lubrication oil properties?
55. Full shaft arrangement of M/E, how is it connected to the propeller, shafts rest on which thing after the engine room?
56. What is a stern tube? where it is? What is the purpose of it?
57. Explain the Valve timing diagram of the loop scavenging and uniflow scavenging?
58. What is SFOC? How it is calculated?
59. Liner calibration which tool?
60. What are the Least count and the Zero error with reference to the micrometer?
61. Fuel Pump – Jerk type and Bosch type
62. MEP – How to calculate? Why calculate?
63. Tie bolt function and diagram
64. Types of turbocharger
65. The main engine is turning on air but not coming on fuel – reasons?
66. Types of ME bedplate.
67. 4 stroke engine for propulsion. Show the entire arrangement.
68. Cylinder oil properties for 2 stroke and 4 stroke. TBN value
69. Crankshaft deflection – How taken? How to draw the graph of Angle vs Deflection? How will you
    check misalignment is due?
70. Safeties for the crankcase. The function of breather pipe, Flashpoint of Lube oil
71. OMD alarm. What % OMD alarm will get activated?
72. Reversing of the main engine. Lost motion principle
73. How are the camshaft & crankshaft connected in M/E? Lubrication arrangement for them
74. Crankshaft deflection – How taken? How to draw the graph of Angle vs Deflection? How will you
    check misalignment is due?
75. Difference between turbochargers of 2 stroke and 4 stroke
76. ME Safeties
77. ME LO line diagram including crosshead lubrication and piston return lines
78. How to calculate power? How it’s done on ship? How to calculate power if there’s no cylmate, no
    digital indicator, and no old-school stylus!
79. RT-Flex distributor reversing, how is it done, construction diagram
80. Draw card & indicator card difference. Then explain Draw Card
81. What is a puncture valve?
82. Difference between ME & MC engines
83. Type of fuel pump in your ship and explain?
84. Why FQS lever is provided?
85. ME cooling water test, values, and action
86. Maneuvering diag.
87. Starting Air Line Explosion – a) What is it? b) Causes c) During maneuvering starting air v/v
    leaking how will you identify which one & what will be your action?
88. Tie Rods: Functions and Pre-Tensioning Method
89. Fuel V/v Diagram and working
90. Turbocharger Surging: explain what is it
91. How propeller torque is achieved?
92. ME lube oil line diagram, showing all components in line?
93. Hydrostatic Hydrodynamic Lubrication
94. Working of VIT?
95. Working of fuel pump?
96. Draw power card, compression card, Difference between peak pr, compression pr, mean effective
    pr
97. Difference between RTA engine and MAN MC engine
98. Safety of T/G and how will u check for an over-speed trip
99. How lubrication takes place in the LMC engine? Crosshead lubrication. How so small pressure is
    maintaining the oil film?
100. Stroke to bore ratio of your engine,
101. How much was SFOC of your ship?
102. What type of lubricator in Sulzer RT FLEX?
103. Longitudinal cross-section of the bellow of exhaust valve?
104. Piston clearances.
105. Scavenge Space inspection.
106. RT Flex lubrication system
107. Stuffing box.
108.  Why turbocharger? Can we run main engines without them? How?
109. All the clearances and why are they given?
110. Reversing in MC engines
111. OMD and its principle
112. Checks to be made while crankcase inspection
113. Crank case explosion
114. How to take all ME bearing clearance and what are the normal values of clearances?
115. Piston crown checks
116. Piston ring clearances
117. Piston checks
118. Cylinder head overhaul
119. Tappet clearance
120. Rocker arm maintenance
121. Fuel pp onboard, type, parts, construction
122. Main engine interlocks,
123. Turning gear interlock, how it works?
124. Power imbalance and catalytic fines
125. Draw maneuvering diagram, tell the position of fuel cam while stopping
126. Draw lube oil circuit of your main engine and what are the alarms and trips provided for lube oil
     only for the main engine?
127. V/v timing diagram of 2-stroke, p-v diagram of same and drawcard for 2-stroke, and then the
     position of TDC on drawcard?
128. How is the chaincase lubricated?
129. How can the chain be tightened if it has become loose?
130. What is the sac volume in a fuel injector?
131. What is the pressure of lube oil at ME main bearings?
132. The line from the expansion tank enters the suction side or discharge side of the JCW pump and
     explain the reason for that
133. Draw main engine lube oil line
134. What is the purpose of having a backflush filter in the LO line?
135. What is the pressure of lube oil at ME main bearings?
136. What is VIT?
137. What type of lubrication used for thrust bearing? Hydrodynamic or hydrostatic lube?
138. LO test report from shore- what all are the contaminants? If iron n copper present in the LO test report what will you check in the engine(which part)? If sodium is present what is the cause?
139. Procedure for taking indicator card
140. How peak pressure measured in the generator? Can we use the same instrument for ME?
141. What is the material of crosshead bearing, telescopic pipe, articulated pipe?
142. What is a piston slap?
143. Not all ships are provided with a planimeter. How to calculate power in that case? Also the
     procedure to find SFOC?
144. MCR, NCR – Definitions? Your ship MCR. NCR?
145. Stresses in A/E and M/E starting from piston to propeller?
146. The line from the expansion tank enters the suction side or discharge side of the JCW pump and
     explain the reason for that
147. How to check the integrity of the piston rod gland without opening it?
148. Why 1.4mm lift is given for injectors? Why not more or less?
149. How is the Tie rod attached to the Bedplate?
150. What UEC stands for?
151. How to find the elongation of the chain in the chaincase? How to measure percentage elongation?
152. What is Mark-1,2,3,4& 5 engine?
153. What is MC,ME,MCC,MCE?
154. What is oil analysis? How it can be used for engine condition monitoring?
155. How will you know without opening anything that it is a two-stroke or 4 stroke Engine?
156. What is the priming of fuel injectors?
157. Difference between lubrication of X-HD in Sulzer RTA n B&W MC engines. Construction and
     operational differences?
158. How to confirm exhaust valve rotation? In man B&W,
159. Why Pulse-type T/C used in AE and Constant Pressure T/C in ME?
160. How to adjust the timing of camshaft relative to crankshaft?
161. Difference between super VIT and VIT?
162. Difference between specific fuel consumption and total fuel consumption?
163. Excessive honing of the liner will lead to?
164. What is supercharging? Construction of turbocharger, the function of each part,
165. JCW Expansion tank- why it is provided? Suppose oil is there from where it can come?
166. Difference between RTA engine and MAN MC engine
167. 6S60MC-C8 wat does C8 stand foR?
168. What is detuner?

Function 4B MEOL: Auxiliary Engine and Related System

1. What to do if the cam of the fuel pump of one of the units of the Aux engine is corroded?
2. Tappet clearance? How will you ensure that the v/v seats are closed (to take tappet)?
3. Tappet Adjustment. How is it done? Where all it can be checked? What happens if wrongly
   adjusted? If no indication on the flywheel, how will you do?
4. How to adjust compression pressure when the generator is running?
5. How is the camshaft & crankshaft connected in A/E? Lubrication arrangement for them
6. How starting air is supplied to the aux engine? Draw & explain. The function of air distributors.
7. Tappet clearance.
8. 4-stroke bottom end bearing clearance. How to take and position of the piston?
9. Draw timing and PV diagram along with piston movements of 4 stroke engine? Dual, Diesel & Otto cycles
10. Draw/explain the LO circuit for AE. How does liner get lubricated? (fav question) oil through gudgeon pin and splash
11. AE – how fuel goes inside? Diagram? Injector overhaul?
12. Additives of A/E L.O.TBN of AE oil?
13. Aux engine liner lubrication
14. Crankcase inspection in an auxiliary engine,
15. How lubrication of liner is done in the aux engine?
16. How to test lube oil trip and over speed trip in aux engine?
17. What impurities can be found in the LO of a generator
18. How does A/E LO get dirty?
19. How does the piston gets lubricated in 2s & 4s? With figure
20. Lube oil consumption increases of the generator after 1000 hrs of decarb? What all possible reason?
21. Overspeed Trip Testing for AE
22. Why 2 springs for 4S valve arrangement?
23. How to identify a unit at TDC without referring to flywheel marking?
24. Why gudgeon pin in the compressor is fixed and free-floating in AE?
25. Difference between auxiliary engine governor and main engine governor.
26. Why we can’t reverse 4 stroke engine directly?
27. The engine is running but not taking the load. What may be the reason?

Function 4B MEOL: Boilers

1. What is a steam trap? Where is it located? Its function? Is there a strainer before it?
2. Position of steam trap in bunker heating steam line?
3. Feedwater line diagram? How will u know the oil on the feed water line?
4. What is Priming of the boiler?
5. How many safety valves are there on Auxiliary Boiler and how does it works? Explain with diagram
6. What are all the safety checks u will carry out before starting a boiler?
7. Why did vent provide on the boiler?
8. Boiler mountings?
9. Why easing gears?
10. Purpose of the expansion tank. How to know the tank is empty or full if you are not able to see the level in the gauge glass.
11. Purpose of boiler register draw n show
12. Why 2 Boiler gauge glasses? How to find if both functioning correctly?
13. About safety valve. Gauging of the valve and its purpose.
14. If oil goes into the boiler how will u come to know?
15. Boiler water treatment: how salt formation takes place through FWG water has salt content 2ppm?
16. Boiler water level is going down – reasons?
17. Boiler gauge glass blowdown.
18. Boiler accumulation of pressure. Test of accumulation of pressure. What are the importance of Boiler low water level trip and alarm? How to try out /test?
19. Types of boiler burner? Explain any 1?
20. Boiler furnace inspection, how will you prepare for that?
21. Draw Boiler feedwater line. In which line is the feedwater regulator? Is it in the mainline or auxiliary line?
22. If one gauge glass show half level and the other showing fluctuation what does it mean?
23. How to know if oil is there in boiler water? What are boiler water treatments?
24. pH of boiler water? Why alkaline? What acidity hazards? Scaling hazards?
25. What if Chloride contents increase?
26. Hydraulic pressure testing of the boiler. Why & How?
27. What is soot? Why do you do soot blow? Draw arrangement of soot blowers on your ship.
28. Draw cross-section of boiler and all the feed water and steam outlet connection and where fitted
    location-wise.
29. Safeties on Boiler?
30. Boiler CW Test, Values & Action
31. Boiler Water Treatment, what if chloride content increases, blowdown procedure, what if Chlorine content continue to increase even after blowdown?
32. What is boiler steam temp?
33. Boiler feedwater line diagram
34. What type of steam trap on deck cargo steam line?
35. Hot well overflowing reasons
36. Boiler water tests? Values? What to do when the value rises? How is the phosphate test done and why is the phosphate test done?
37. What information is provided on the safety valve?
38. Boiler safeties
39. There is no water in the boiler – What action will you take?
40. Boiler gauge glass, boiler leak off alarm why?
41. Why do you blow down the boiler and how?
42.  What do u mean by boiler panting?
43. What do u mean by boiler running in?
44. Purpose of ignition transformer?
45. Effects of water getting carried over the boiler
46. Boiler double banking
47. How much was the pre and post-purge time? Can u change that and how to find the min amount of purge time(if there is no manual)?
48. What is boiling point of a liquid?
49. nitrate in jacket water should be around 1400 ….what will happen if nitrate comes below this level. what may be the reason for falling nitrate
50. Floating of boiler safety valve is done during drydock survey
51. How is boiler feedwater control connected to boiler combustion control?
52. Manual firing of the boiler
53. Why feed water p/p lose suction if feedwater temperature is too high?
54. How to adjust the air-fuel ratio in a boiler?
55. How to fire the boiler manually?
56. Methods for detection and taking out oil from hotwell?
57. What is Primary and Secondary Air Combustion in Boiler?
58. Why multistage pump for boiler feedwater?
59. What actions to be taken for the following-for boilers
    1.low ph or acidic condition
    2.high alkalinity
    3.high tss
    4.hydrazine.
60. What will happen if steam traps are not used in the steam system?
61. What is the voltage supplied to the pilot burner in the boiler and how?
62. Hide-out
63. Why are the two safety valves in a boiler set at different pressures?
64. Types of steam traps. Working. Purpose and location
65. REASON FOR BOILER FEEDWATER CASCADE TANK OVERFLOW WHILE MANOEUVRING?
66. Why a high lift safety valve is called a high lift safety valve?
67. What is wing clearance in the boiler safety valve? wing clearance = lip clearance
68. Boiler precautions to be taken before starting.

Function 4B MEOL: Refrigeration and Air Conditioning

1. How will you detect moisture in the ref system? What will u do to remove it?
2. What is condenser and evaporator pressure?
3. State of refrigerant before and after TEV?
4. What is short cycling and reasons?
5. Explain TEV?
6. In the ref plant, if there is oil in the evaporator, how will you clean it?
7. Detailed drawing of refrigeration system
8. Reasons for domestic refrigeration not undergoing HP trip.
9. Name the refrigerant used in the air conditioning system?
10. Reefer plant. Why back pressure v/v? What is the function of the solenoid?
11. Cut in cut out
12. Low refrigerant – How will you get to know?
13. Leakage detection. You carried out leak test rectified and still refrigerant is leaking. Why and from where?
14. Capacity of recovery bottle?
15. Reefer short cycle
16. A/C not providing cooling. Reasons?
17. Ref charging methods? Where is the point for charging? Where else you can have the point to charge the refrigerant? Explain the method of charging
18. Loading & unloading of AC compressor – Explain
19. Difference between AC compressor & Air compressor unloader
20. Why in the Refrigeration system there is Equalising line? What about which is not having Equalising line. how superheat is created in it?
21. Difference between the AC compressor and air compressor crankcase design and its venting arrangement?
22. Reefer compressor unloading with diagram
23. Draw refrigeration cycle and principle of refrigeration?
24. Refrigeration lines- Overcharging, short cycling, what if moisture is present? Where heat is added and where heat is removed in the refrigeration system?
25. The procedure of refrigerant charging (gas) in ac plant, and what precautions are taken for personal safety?
26. Working of TEV?
27. Location of drier in domestic reefer
28. Domestic Refrigerator Compressor type
29. Draw refrigeration cycle? What is latent heat etc?
30. Safeties on reefer. Why belt driven?
31. Difference between cut out and trips in reference to the refrigeration plant?
32. How A.C system capacity control takes place?
33. How to fill Lub oil in a refrigeration compressor?
34. How is the load decided on AC compressor and how does it work?
35. How is the cold room temperature maintained?
36. What’s the difference between air compressor lube oil and refer lube oil properties?
37. Air vent of refrigeration & air compressor difference?
38. Difference between LP cutout and LP controller?
39. what is cascade refrigeration system? tell me construction, how temp is maintained to -165 degree.
40. Lube oil charging in ref compressor during running, Construction of charging v/v
41. What all parameters to be checked in a refrigeration compressor?
42. What are the reasons for the suction line getting hot/ cold?
43. Frosting in the suction line… Causes?
44. What is a back pressure valve? And where it is used?

Function 4B MEOL: Purifiers

1. Purifier overflowing reasons
2. What is the main function of gravity disc? What shape? What passes through, what effect of its sizes, how it exactly controls oil-water interface? What will happen with the wrong selection? How to select the exact size?
3. Principle of the purifier, draw a diagram, why it is necessary to heat the oil, the temperature you maintained on your ship for FO and LO? And why that much temp only?
4. How to start a purifier?
5. Approach towards rectifying a fault in the purifier and what if oil is leaking?
6. How to select a gravity disc?
7. Why we stop purifiers with the help of a hand brake every time?
8. Why brake on purifier?
9. Why purifier brakes are applied during stopping. Is there any arrangement that the critical speed is bypassed very fast for purifiers?
10. Why do we apply the brake to purifier at the time of stopping? And what is the arrangement to
    overshoot the critical rpm at time of starting?
11. Why brake is given to purifier?
12. How is the vertical shaft and horizontal shaft of purifier alligned?
13. What is the function of the friction clutch mechanism used in purifiers?
14. Safeties on Purifier
15. Purifier working principle
16. Manual desludging of Pfx?
17. Safety in purifier?

Function 4B MEOL: Compressors and Air system

1. Why compressors are there in more than one stage?
2. Why we use intercooler & after cooler?
3. Bumping clearance
4. What all factors affect vol. efficiency?
5. Air compressor overhaul and valve overhaul. How to test it properly overhauled?
6. Bumping clearance. What will happen if it is more and if it is less? How is it?
7. PV diagram for Air compressor – Difference between Isothermal/Adiabatic Compression
8. Multistage compression, why, operation, principle, what type of compressor
9. Compressor unloader working, if 1st stage suction and discharge v/v leaking what will be the
   effect, how lubrication is done, profile for lubrication in comp crankshaft, exact profile.
10. WHAT ARE THE DIFFERENT TYPES OF COMPRESSOR VALVES?
11. Compressor 2 stage PV diagram
12. Compressor specifications and inspection inside the crankcase
13. Where safety valve is fitted? Which side and why?
14. Compressor safeties
15. Multistage Compression, PV Diagram, Safeties.
16. Starting air bottle safeties
17. What happens when the fusible plug melts?
18. What all you will check-in air compressor crankcase?
19. Why is an air compressor started unloaded?
20. How does the air compressor start and stop automatically?
21. What will happen if the suction and discharge valve of air compressor got interchanged after
    overhaul?
22. Will the reciprocating compressor work, if the direction of the motor changes? Explain?
23. In a two-stage tandem air compressor adjusting the first stage bump clearance will affect the
    bump clearance in the second stage, so how does it work out?
24. Can we use shims to adjust bumping clearance in air compressors?
25. How does the air compressor start and stop automatically?

Function 4B MEOL: Pumps and Pumping system

1. Multi-stage pump and its diagram,
2. NPSH of pump Barik
3. Class survey of ballast pump what are your preparations
4. Casing ring & wear ring location its function
5. How multistage centrifugal pumps connected in parallel &series? It’s application
6. OWS 3 way valve testing
7. Different types of pumps used in engine room
8. Where you will use centrifugal pump and where you will use reciprocating pump?
9. What is NPSH? Factors affecting NPSH?
10. Draw a diagram of the gear pump.
11. Why Pump Vibrates?
12. OWS – how it works? What principle? Why do you fill it with seawater?
13. If you start the main seawater pump and it trips what are the reasons?
14. Centrifugal p/p – clearance between wear ring & casing
15. Cargo pump type and their bearing lubrication, details
16. If there are two different types of cargoes in two adjacent tanks- one greater than another. pump is tripping on overload which discharging higher SG cargo. So how will you discharge the cargo of that tank?
17. Where emergency bilge suction is fitted? Which pump and why? How will you test? Who will test? Procedure
18. Mechanical seal diagram and function. Function of lantern ring in centrifugal pumps.
19. Bilge line not taking suction?
20. Centrifugal pump – part names
21. If you start the main seawater pump and it trips. What are the reasons?
22. How to start a seawater pump?
23. Centrifugal p/p cross-section, working and for some reason diag of rotation. Wear ring. Gland.
24. Difference between mech seal and oil seal?
25. Why gear pump not used for emgcy fire pump as it develops high pressure?
26. Difference between centrifugal and gear pump
27. How to check the correct working of 15 ppm alarm?

Function 4B MEOL: Steering Gear and Hydraulic system

1. What is the Safematic system?
2. Hunting gear, oil flow, and safety in the steering gear.
3. Steerig gear test before departure
4. Hydraulic system of windlass. What is the hydraulic symbol of pump and motor?
5. How winches operated on your ship?
6. What are the primary purpose of hydraulic fluid on board?
7. Difference between steering gear motor and other motors onboard
8. Draw the 4 ram steering gear and explain how it works? How are the pumps controlled?
9. What is 100% redundancy?
10. What are the follow-up, non-follow-up, and automatic systems of control systems in steering gear?

Function 4B MEOL: Fresh Water Generator and FW system

1. Vacuum loss occurred in the freshwater generator. How will you come to know without a pressure gauge?
2. Freshwater generator principle?
3. Start the freshwater generator, the principle of freshwater generation, working of ejector?
4. How will you start FWG?
5. Freshwater generator. working. Eductor pump working. Salinometer working.
6. FWG not producing vacuum – Reasons
7. Freshwater generator working and problems
8. Principle of FWG? Reverse osmosis and vacuum FWG?

Function 4B MEOL: Miscellaneous

1. What is plasticity & elasticity?
2. 2E asks you to cut threads using a lathe. How will u carry out the job? Speed of lathe machine? Tools used?
3. Steering gear failure. It is not responding from the bridge – Causes?
4. What is the maximum angle did your hose lifting crane moved?
5. Difference b/w cut-out & trip?
6. Why air vents are provided in tanks?
7. What is jumping clearance?
8. What are the types of welding?
9. How many sea-chest on board, why high sea chest in port?
10. Difference between the relief valve and the safety valve?
11. In the bunker analysis report what all items are given?

These are a few of the most frequently asked MEO Class 4 Oral questions in MMDs. But, don’t be limited to only these questions. The more questions you solve, the more confident you’ll answer in orals. MEO Class 4 Oral questions can be found from different sources such as forums, WhatsApp groups, Telegram Groups, Facebook groups, and websites.

So, this was a complete set of MEO Class 4 Oral Questions asked on Function 4B. That includes important questions on Main Engine, Aux Engine, Purifiers, Boilers, Compressors, and all other important systems. I hope you found this article helpful.

And, if I have missed any important topic to add, please drop it in the comments.