2nd Class Fireman
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What is Potential Energy?
What is Kinetic Energy?
- Potential Energy is energy pocessed by reason of position or deformation
- Kinetic Energy is energy pocessed by reason of motion.
What is the 1st law of Thermodynamics?
What is the 2nd law of Thermodynamics?
- 1st: Energy cannot be created or destroyed, only converted from one form to another
- 2nd: No machine can both continuously and completely transform heat into mechanical energy, no machine is 100% efficient.
Name 3 ways that heat is transferred
What is a British Thermal Unit?
The heat required to raise the temp. of one pound of water one degree F.
Convert 22 Deg. C to Fahrenheit
22C = 71.6F
How many BTU's are required to raise 1 lb of water from 50F to 210F
How many BTU's are required to raise the temperature of 500 gallons of water from 70F to 160F
- 1 gallon of water weighs 8.33 lbs
- 500x8.33=4165 lbs
- 160 - 70= 90
- 90 x 4165= 374850 BTU's
How much does 2,000 gallons of water weigh
2,000 x 8.33=16,660 lbs
The pressure gauge reads 130 psi, What is the ablolute pressure?
130 + 14.7=144.7psia
What is Latent Heat of Fusion?
The heat required to change 1.0 lb of a solid into a liquid at the same temperature
What is the Latent Heat of Evaporation?
The heat required to change 1.0 lb of liquid into a pound of gas at the same temperature.
How many BTU's are in one pound of steam at 212 deg F
- 180(water from 32 to 212)+ 970.3 latent heat
- Total=1150.3 BTU's
What is sensible heat?
What is Latent heat?
- Sensible heat is heat added to a substance that causes a change in temp. that can be measured.
- Latent Heat is heat added to a substance that causes a change of state without a change in temp.
What is the critical pressure of steam?
What is the critical temperature of steam?
705.4 deg F
What happens to the boiling point of water as the pressure increases?
The boiling point of water (saturation temp.) increases.
A boiler is equipped with one safety valve. Where will it beset to blow?
At or below the M.A.W.P. (max allowable working pressure)
What happens to the Enthalpy of Evaporation as the presssure increases?
The Enthalpy of Evaporation decreases.
What are the three states of matter?
Solid, liquid, and gas
What is the definition of specific heat?
The heat required to raise the temperature of one pound of any substance one degree F.
A boiler is equipped with 3 safety valves, where can they be set?
One at or below the MAWP, one could be set 3% above the MAWP, and the third would be within 10% of the highest set safety valve.
Where is the superheater safety valve set?
The superheater safety valve is the lowest set safety valve to assure flow thru the superheater to prevent overheating.
Name 3 methods used to determine the minumum safety valve relieving capacity.
- Table PG-70 (Code constants)
- Code formula(w=c X h X .75 divided by 1100)
- Accumulation test
Why does a safety valve pop open?
Because of the huddling chamber, an increased area of the disk is subjected to high pressure steam quickly overcoming spring tension.
What type of valve is permitted between the boiler and the safety valve?
No valves are permitted
How are soot blowers classified?
Stationary or retractable.
What precautions should be taken prior to soot blowing?
- Increase air flow
- Drain steam lines to soot blowers
- Blow soot from the furnace outward
How are opacity excursions handled during soot blowing?
Stop blowing soot, and proceed slowly to avoid further excursions.
If you fail a written exam, when can you apply again?
What is the purpose of a steam trap?
To remove air (non-condensable gases) and water from steam lines without the loss of steam.
Name 3 types of steam traps.
- Inverted bucket trap
- F+T trap
- Thermostatic trap
Describe the operation of any steam trap.
The inverted bucket will rise or fall depending on conditions at the steam trap. Live steam will impart buoyancy to the bucket, causing it to rise and closing the valve to the trap discharge. Condensate will cause the bucket to fall or sink opening the valve to the discharge. The cycle repeats.
How would you know a steam trap was not working?
- Steam process not working
- Trap not cycling
- low or no temp. differential across the trap
- high condensate returns
If you fail a written exam, how soon can you apply again?
Where is a non-return valve located?
As close to the boiler as possible.
Explain how you find the true water level.
Blow down water column and gauge glass.
How often must air tanks be inspected?
Tanks above 50 psi should be inspected every 2 yrs
How often should high pressure boilers be blown down?
Once a day, or based on water analysis.
Can you stop a safety valve from chattering by taking up on the adjusting nut?
Adjustments on safety valves can only be made by the manufacturer or his authorized representative.
Combustion is a chemical process in which a combustible unites with oxygen producing heat and often light
What is perfect combustion?
Burning fuel completely while using the theoretical amount of air required. (Not possible)
What is complete combustion?
What is incomplete combustion?
- Burning the fuel completely using the minumum amount of excess air. (desirable)
- Not burning all the fuel. (not good)
What is spontaneous combustion?
A type of combustion that occurs without an external ignition source.
What 3 conditions are necessary for complete combustion
What are the combustibles in fuel?
Carbon, Hydrogen, and Sulphur
What is primary air?
What is secondary air?
Air supplied to the burner with the fuel that controls the rate of combustion and amount of fuel that can be burned.
Air supplied to the combustion process that controls combustion efficiency (how completely fuel is burned)
What is excess air?
The amount of air supplied to the combustion process that is greater than the theoretical amount required.
What is viscosity?
The internal resistance of fuel oil to flow.
What is Flash Point?
The temperature that an oil will ignite with a pop but will not continue to burn.
What is Fire Point?
The temperature that an oil will ignite and continue to burn.
What is Pour Point?
The lowest temperataure at which an oil will still flow.
Name 3 ways to atomize #6 oil.
- Rotary cup burners (mechanical burner)
- Pressure Atomizing Burner (use high press.)
- Steam/Air Atomizing Burner (use steam/air pressure)
Give 5 reasons a boiler burning #6 oil would smoke.
- Moisture in oil
- Inpurities in oil
- Not completely atomized
- Too much air
- Not enough air
Name the components of a #6 fuel oil system.
- Storage tanks
- Oil pumps
- Oil strainers
- Oil heaters
- Oil pressure gauges
- Thermometers to monitor fuel temp.
- Oil burner
Name the 4 types of draft found in power plants.
How is draft measured?
By using a manometer which measures in inches or tenths of an inches of a vertical water column.
What is draft?
The difference in pressure between two points that cause air or gas to flow.
What is the greatest heat loss in a boiler?
Heat loss thru the stack
How many BTU's in a gallon of #6 oil?
How many gallons in a barrel of fuel oil?
42 US gallons
What is the specific gravity of fuel oil?
less than 1.0
What do you do if the flame is lost while burning #6 oil?
- Secure the fuel (close fuel valves)
- Purge the furnace, and attempt to relite.
- Troubleshoot the cause
What is opacity violation?
- Smoke density from stack exceeding state and federal regulations(Ringleman Chart)
- (opacity greater than 20% for more than 6 minutes in any one hour, or greater than 40% at any time)
What is the proper procedure for relieving the watch?
Walk thru the boiler room and check the water level in all operating boilers, check auxiliary equipment ,read the log book and talk with relief.
Explain the difference between saturated steam and super heated steam.
- Saturated steam is steam at a temperature corresponding to it's pressure.
- Super heated steam is steam at a temperature that is higher than the temperature corresponding to it's pressure.
Explain how you would replace a broken gauge glass.
Isolate the gauge glass and open the gauge glass drain. Remove any broken glass by blowing out the gauge glass connections. Get a new glass and put new gaskets and the nuts on the glass. Put the gauge glass in place and lift the glass off the bottom connection while you hand tighten the nuts. Temper the glass by cracking the steam connection. Close the drain and place the gauge glass in service. Tighten the nuts with a wrench if needed.
How often should the safety valves be tested?
Safety valves should be hand lifted at 75% of working pressure during every start-up of a boiler.
What precautions should you take before entering an off-line boiler?
Make sure all sources of energy are isolated and locked and tagged out. Test the environment for sufficient oxygen levels and never enter a confinded space without an outside person.
Name 3 ways the heating value of fuel is determined.
- Bomb calorimeter
- Ultimate analysis, used with DULONGS FORMULA
- Proximate analysis
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