MULTIPLE CHOICE QUESTIONS ON INDUSTRIAL SAFETY

1-Probability of the event that might occur X Severity of the event if it occurs =

(A) Accident

(B) Hazard

(C) Risk

(D) None of the above

(Ans: C)

2-Industrial safety management if that branch of management which is concerned with ______ hazards from the industries.

(A) Reducing

(B) Controlling

(C) Eliminating

(D) All of the above

(Ans: D)

3-The following is indirect cost of accident

(A) Money paid for treatment of worker

(B) Compensation paid to worker

(C) Cost of lost time of injured worker

(D) All of the above

(Ans: C)

4-The following is(are) physical hazard agent(s)

(A) Falls

(B) Electricity

(C) Inhalation

(D) All of the above

(Ans: D)

5-Check list for Job Safety Analysis (JSA) consists of

(A) Work area, material, machine, tools

(B) Men, machine, material, tools

(C) Men, machine, work area, tools

(D) Men, work area. Material, tools

(Ans: A)

6-A safety programme consists of

(A) Three E’s

(B) Four E’s

(C) Five E’s

(D) Six E’s

(Ans: B)

7-For household wiring and small units, the following should be used for safety measure

(A) MCB

(B) ACB

(C) OCB

(D) MCCB

(Ans: A)

8-Which of the following colour is used for radiation hazard?

(A) Red

(B) Orange

(C) Green

(D) Purple

(Ans: D)

9-Decibel (db) is a unit used to measure

(A) Light

(B) Sound

(C) Frequency

(D) None of the above

(Ans: B)

10-The following is (are) are generally provided with limit switch to prevent motion beyond preset limit

(A) Hoists

(B) Conveyors

(C) Machine tables

(D) All of the above

(Ans: D)

11-The following is (are) used as safety device(s) in machines

(A) Fail safe

(B) Safety interlocks

(C) Limit switches

(D) All of the above

(Ans: D)

12-Class-A fire consists of fire due to

(A) Wood

(B) Oil

(C) Transformer

(D) Chemical

(Ans: A)

13-Water is used to extinguish

(A) Class-A fires

(B) Class-B fires

(C) Class-C fires

(D) All of the above

(Ans: A)

14-The following class of fire occur in electrical equipment

(A) Class-A fires

(B) Class-B fires

(C) Class-C fires

(D) All of the above

(Ans: C)

15-The following extinguisher is suitable for cotton or other textile fire

(A) Water

(B) Soda acid

(C) Foam

(D) Dry chemicals

(Ans: D)

16-_____ is best suited to extinguishing oil or flammable liquid fire.

(A) Soda acid

(B) Vaporizing liquid

(C) Foam

(D) Dry chemical

(Ans: C)

FACTORS AFFECTING FLAME PROPAGATION

Rate Of Flame Propagation Affects The Combustion Process In Si Engines. Higher Combustion Efficiency And Fuel Economy Can Be Achieved By Higher Flame Propagation Velocities. Unfortunately, Flame Velocities For Most Of Fuel Range Between 10 To 30 M/Second. 

The Factors Which Affect The Flame Propagation's Are 

1. Air Fuel Ratio
2. Compression Ratio
3. Load On Engine
4. Turbulence And Engine Speed 
5. Other Factors

A:F Ratio: The Mixture Strength Influences The Rate Of Combustion And Amount Of Heat Generated. The Maximum Flame Speed For All Hydrocarbon Fuels Occurs At Nearly 10% Rich Mixture. Flame Speed Is Reduced Both For Lean And As Well As For Very Rich Mixture. Lean Mixture Releases Less Heat Resulting Lower Flame Temperature And Lower Flame Speed. Very Rich Mixture Results Incomplete Combustion And Results In Production Of Less Heat And Flame Speed Remains Low. 

Compression Ratio: The Higher Compression Ratio Increases The Pressure And Temperature Of The Mixture And Decreases The Concentration Of Residual Gases. All These Factors Reduce The Ignition Lag And Help To Speed Up The Second Phase Of Combustion. The Maximum Pressure Of The Cycle As Well As Mean Effective Pressure Of The Cycle With Increase In Compression Ratio. Higher Compression Ratio Increases The Surface To Volume Ratio And Thereby Increases The Part Of The Mixture Which After-Burns In The Third Phase.

Load On Engine: With Increase In Load, The Cycle Pressures Increase And The Flame Speed Also Increases. In S.I. Engine, The Power Developed By An Engine Is Controlled By Throttling. At Lower Load And Higher Throttle, The Initial And Final Pressure Of The Mixture After Compression Decrease And Mixture Is Also Diluted By The More Residual Gases. This Reduces The Flame Propagation And Prolongs The Ignition Lag. This Is The Reason, The Advance Mechanism Is Also Provided With Change In Load On The Engine. This Difficulty Can Be Partly Overcome By Providing Rich Mixture At Part Loads But This Increases The Chances Of After Burning. The After Burning Is Prolonged With Richer Mixture. In Fact, Poor Combustion At Part Loads And Necessity Of Providing Richer Mixture Are The Main Disadvantages Of Si Engines Which Causes Wastage Of Fuel And Discharge Of Large Amount Of Co With Exhaust Gases.

Turbulence:Turbulence Plays Very Important Role In Combustion Of Fuel As The Flame Speed Is Directly Proportional To The Turbulence Of The Mixture. This Is Because, The Turbulence Increases The Mixing And Heat Transfer Coefficient Or Heat Transfer Rate Between The Burned And Unburned Mixture. The Turbulence Of The Mixture Can Be Increased At The End Of Compression By Suitable Design Of The Combustion Chamber (Geometry Of Cylinder Head And Piston Crown). Insufficient Turbulence Provides Low Flame Velocity And Incomplete Combustion And Reduces The Power Output. But Excessive Turbulence Is Also Not Desirable As It Increases The Combustion Rapidly And Leads To Detonation. Excessive Turbulence Causes To Cool The Flame Generated And Flame Propagation Is Reduced. Moderate Turbulence Is Always Desirable As It Accelerates The Chemical Reaction, Reduces Ignition Lag, Increases Flame Propagation And Even Allows Weak Mixture To Burn Efficiently. 

Other Factors: Among The Other Factors, The Factors Which Increase The Flame Speed Are Supercharging Of The Engine, Spark Timing And Residual Gases Left In The Engine At The End Of Exhaust Stroke. The Air Humidity Also Affects The Flame Velocity.

All About 3D Printing

Characteristics of Materials

EXPLANATION OF HVAC

HVAC stands for Heating Ventilation and Air-Conditioning , is commonly associated with heating and cooling industry. is a system or machine that performs three major functions by its three separate ducts i.e heating, cooling and ventilation of air, generally used in residential commercial or Industrial buildings.

It is really worthwhile to learn this technology specially for the candidates and working professionals who belongs to Mechanical Engineering background, because the working process and designing parts are included in their course curriculum like Thermodynamics, Fluid Mechanics, Heat and Mass Transfer, Refrigeration and air conditioning, Machine Design, CAD, etc. I must say the learning of HCAC would be more beneficial for working experience to boost up their career, while for fresher I think it could be learn in combination with CAD/CAM/Catia for getting a good platform to start their professional life.

Knowledge of these subjects are a essential for a HVAC engineer:

1. Thermodynamics
2. Fluid Mechanics
3. Heat & Mass Transfer
4. Refrigeration and Air Conditioning
5. Transport Phenomena (additional)
6. Computational Fluid Dynamics (additional)
7. Power Plant Engineering (additional)

Scope of HVAC;

1. HVAC Design Engineer
2. HCAC Maintenance Engineer
3. HVAC Shift Engineer
4. HVAC Supervisor
5. HVAC Site Engineer etc

CRDi ENGINE

Common rail direct fuel injection is a direct fuel injection system for  diesel engines.

In diesel engines, it features a high-pressure (over 1,000 bar or 100 MPa or 15,000 psi) fuel rail feeding individual solenoid valves as opposed to a low-pressure fuel pump feeding unit injectors (or pump nozzles). Third-generation common rail diesels now feature piezoelectric injectors for increased precision, with fuel pressures up to 3,000 bar (300 MPa; 44,000 psi).

In Common Rail Direct Injection, commencement of combustion takes place directly into the main combustion chamber located in a cavity on the top of the piston crown. Today, CRDi technology is being widely used to overcome some of the deficiencies of conventional Diesel engines which were sluggish, noisy and poor in performance when implemented especially in passenger vehicles.

Working of CRDi –

1. Pressure generation takes place in the high-pressure pump. The pump compresses the fuel at the pressures at about 1,000 bar or about 15,000 psi.
2. It then supplies the fuel via a high-pressure pipe to the inlet of the rail. From there, the fuel is distributed to the individual injectors, which inject it into the cylinder’s combustion chamber.

CRDI engine contains a small tube called Common rail where the injectors are connected and contains fuel at a constant high pressure of 1,350 bars. The CRDI engine small amount of fuel into the engine before the actual charge and another one afterwords.The high pressure in common rail ensures that when it injected the fuel atomizes to a very high degree and mixes evenly with the air, thereby it making very clean exhaust gas. The engine timing of fuel injected is controlled by ECU depending upon the variables such as engine speed, load, engine temperature etc.. The injectors have very precise dose of diesel into each cylinder and ECU makes sure the fuel injected at optimum moment. "This ensures lower emissions, and allows better fuel economy.

Components of CRDi System –
1. High Pressure Fuel Pump
 2. Common Fuel Rail 
3. Injectors 
4. Engine Control Unit

Advantages of CRDi:

1. Pressurized fuel is always present in the fuel line

2. Multiple injections are easily possible

3. Requisite amount and atomized fuel can be supplied, this reduces emissions.

MULTIPLE CHOICE QUESTIONS ON BOILERS

MULTIPLE CHOICE QUESTIONS ON BOILERS :-

The following are the fire tube boilers except

1. Cochran
2. Lancashire
3. Locomotive
4. Babcock and Wilcox

(Ans:d)

The following are the water tube boilers except

1. Stirling
2. Lancashire
3. Yarrow
4. Babcock and Wilcox

(Ans:b)

Which of the following is a low pressure boiler?

1. Babcock and Wilcox
2. Velox
3. Lamont
4. Cochran

(Ans:d)

In fire tube boilers, pressure is limited to

1. 16 bar
2. 32 bar
3. 48 bar
4. 64 bar

(Ans:a)

The following is an accessory of a boiler.

1. Pressure gauge
2. Safety valve
3. Fusible plug
4. Superheater

(Ans:d)

The following is a boiler mounting.

1. Feed pump
2. Water level gauge
3. Economizer
4. Superheater

(Ans:b)

The impurities are removed from boiler with the help of

1. Safety valve
2. Blow off cock
3. Stop valve
4. Fusible plug

(Ans:b)

The boiler consists of horizontal fire tubes is

1. Cochran
2. Cornish
3. Babcock and Wilcox
4. Stirling

(Ans:a)

The boiler commonly used in sugar mills is

1. Cochran
2. Cornish
3. Lancashire
4. Stirling

(Ans:c)

Which of the following is a bent tube boiler?

1. Cochran
2. Cornish
3. Lancashire
4. Stirling

(Ans:d)

The boiler works on a forced circulation is

1. Cochran
2. Lamont
3. Lancashire
4. Stirling

(Ans:b)

The following boiler makes use of pressurized combustion

1. Velox
2. Benson
3. Loeffler
4. Lamont

(Ans:a)

Which of the following is used to heat the feed water by using waste heat of flue gases?

1. Air preheater
2. Superheater
3. Economizer
4. Steam separator

(Ans:c)

__________ is generally placed after the economizer

1. Air preheater
2. Superheater
3. Evaporator
4. None of the above

(Ans:a)