Heat exchangers are devices that

transfer heat from one fluid to another

There are many types of heat exchangers. The three most common types used in the Coast Guard are:

Shell and tube, Fin and tube, Plate type.

Before conducting a thorough cleaning of a heat exchanger you should

conduct a preliminary inspection.

Clean the tube sheet and the inside of the shell using

 fresh water and either a stiff nonmetallic brush or a plastic scraper.

High-Pressure water jet is generally the best method for cleaning

tubes, as it removes all soft fouling

Plate type heat exchangers are made up of

parallel metal plates separated by gaskets.

Plate type heat exchangers:

When removing the plates to clean them

The primary goal of inspecting a plate type heat exchanger

is to detect leaks

Removing soft fouling in tubes can be done using

high pressure water jet brushes air or water gun degreasing solution knotted rope or phenolic disk scraping tool.

Back flushing is only required for

seawater –cooled plate type heat exchangers.

When is Back flushing for seawater –cooled plate type heat exchangers done when

It is not done according to maintenance schedule it is done when the pressure drop through the unit increases by 10 psi (as compared to a clean unit.

What are the two types of auxiliary boilers

fire tube boilers & water tube boilers.

The advantage of fire tube boilers

are simple to operate  less maintenance and inexpensive to build……disadvantages of this are long warm up time and weight of unit compared to the amount of steam produced.

The advantage of water tube boilers are

less warm up time ratio of size and weight to steam produced…….the disadvantages are requires more maintenance  and there expensive to build.

Sensible heat is

·        is heat applied to room temperature water the temperature of the water rises. This is called sensible heat……sensible heat causes a change in temperature.

 Latent heat is when the water saturation temperature reaches what temperature

( in this case 212 degrees F) the temp stops rising even though heat is still being applied. At this point the water is changing from a liquid to a gas.

Saturation temperature is

the temperature at which water boils.

On a Way-Wolff boiler the fuel oil filter is used to

remove fine particulate matter from the fuel before entering the pump

On the fuel nozzle for the boiler the nozzle will have a set of numbers stamped on the body of each one…

what are the numbers for

The first set tells how much fuel passes through it in Galons per hour (gph) and The second set is the angel of spray.

Providing steam for propulation is not the purpose of an

auxiliary boiler.

The purpose of the distillate cooler is to

lower the temperature of the distillate as the feed water is heated.

Operation of the feed temperature regulator automatically controls

 the feed rate.

Operation of the feed temperature regulator automatically controls the feed rate. What is the operational range?

What is automatically tripped by a salinity cell to divert the flow of water to the bilge to prevent contamination of the potable or reserve feed water systems

Three way solenoid-operated trip valves.

While starting the flash type evaporator:

Step 10 is to

prepare chemical feed treatment system for the correct mode of operation. 3 parts per million (ppm)

If the water level appears over halfway in the sight glasses that are mounted on the front of the flash type evap unit; this situation could be caused by a

restricted flow of the feed water between flash chambers or by…. Faulty operational of the brine overboard pump through the over throttling of brine over board discharge valve.

When the steam feed water heater shell pressure decreases from approximately 11 inches hg to 0 you should

perform a cleaning procedure

Distillate is being diverted to waste via three-way solenoid trip valve when the chloride content of the distillate leaving the distillate cooler is

Below .25 grains per gallon.

The oil content detector (OCD) on an OWS uses an

optical system based on the principles of light scattering

The green light illuminates when

water is being discharged from the system.

Prior to trouble shooting an OWS, ensure that all safety requirements are adhered to regarding

personnel, equipment, and environmental safety.

Rapid cycling between operations and oil discharge could

air leak in the system defective probe amplifier relay or defective oil sensing probe.

The three types of coalescing media that improve the efficiency of oil removal are

metal plates replaceable filters and brush assemblies.

One disadvantage of hydraulics is

is the initial instillation expense and component replacement costs are high.

Hydraulic pressure working on the cap end area forces

the piston rod to extend.

Hydraulic pressure working on the cap end area forces the piston rod to extend. The second is the net area.

That is the hydraulic pressure working on the net area forces the piston rod to retract.

Before working on a hydraulic system is sure you completely depressurize

the section of the system you will be working on.

Saturation values for some (2190TEP) fluids have been measured as

130 to 250 ppm at 60 degrees C (140 degrees F) Evaporating trace amounts of water are removed from the fluid heating the fluid reservoir to 140 degrees F

Non positive displacement pumps are not used in

hydraulic systems. Positive displacement includes gear vane and piston.

The two types of filters and strainers are

Full flow and Proportional flow filters.

PASCAL’s law…states

 pressure that is applied to a confined liquid is transmitted undiminished in all directions and acts with equal force on equal area.

Two types of A/C motors include

the induction motor and synchronous.

An AC motor is particularly well suited

constant speed applications.

Wound-rotor in wound-rotor designs, the permanent magnets used in

the squirrel-cage motor are replaced by a rotor having windings.

Virtually all electric motors use

magnetic field rotation to spin their rotors

Squirrel cage motors the rotor consists of permeable metal containing

embedded strips of magnetic material

A synchronous AC motor is not widely used as the induction type motor because of

having a more complex and expensive rotor design.

Absolute switches are used where pressures are to be measured independently of the

natural fluctuation in atmospheric pressure.

The knife switch is rarely used and is most easily demonstrates

the functioning of a switch.

Torque is information not found on

the nameplate data label

A limit switch is an electromechanical device that requires physical contact between the

targets objects and switch activator to make the contacts change state.

A/C motors and switches:

 Two types of A/C motors include

the induction motor and synchronous.

A/C motors and switches:

Wound-rotor in wound-rotor designs, the permanent magnets used in the squirrel-cage motor are replaced 

by a rotor having windings.

A/C motors and switches:

 Virtually all electric motors use magnetic field rotation to

spin their rotors

A/C motors and switches:

Limit switches are electromechanical devices that require 

physical contact between a target object and switch activator to make the contacts change state.

Hydraulic systems:

What are the use of  disadvanatages that hydraulics poses

Initial installation expense and component replacement cost are high, operate at high pressures, fluid can be flammable.

Hydraulic systems:

 Calculate the piston area when force and pressure are known, the formula used is

Area = Force /Pressure

OWS:

 The green light illuminates when

OWS:

 Prior to trouble shooting an OWS, ensure that all safety requirements are adhered to regarding

personnel, equipment, and environmental safety

Flash Type evaporation:

What are automatically tripped by a salinity cell to divert the flow of water to the bilge to prevent contamination of the potable or reserve feed water systems 

three way solenoid-operated trip valves.

Flash Type evaporation:

 For cleaning procedures of a flash type evaporator slowly mix apporxmitly 25 lbs of acid powder in the mixing tank.

How long should you circulate the acid soultion for?

You should circulate it for approxmitly one hour.

AUX Boilers:

What are the two types of auxiliary boilers 

fire tube boilers & water tube boilers

AUX Boilers:

 What are the advantages of water tube boilers

less warm-up time & Ratio of size and weight to steam produced.

AUX Boilers:

The disadvantages of water tube boilers are 

they require more maintenance & are expensive to build

AUX Boilers:

 Latent heat is when

the water reaches the saturation temperature ( in this case 212 degrees F) the temp stops rising even though heat is still being applied. At this point the water is changing from a liquid to a gas.

 Heat exchangers:

Heat exchangers are devices that 

transfer heat from one fluid to another

Heat exchangers:

There are many types of heat exchangers. The three most common types used in the Coast Guard are

Shell and tube, Fin and tube, Plate type.

Heat exchangers:

Before conducting a thorough cleaning of a heat exchanger you should 

conduct a preliminary inspection.

Heat exchangers:

 Clean the tube sheet and the inside of the shell using

fresh water and either a stiff nonmetallic brush or a plastic scraper.

 Heat exchangers:

 High-Pressure water jet: this is generally the best method for cleaning

tubes, as it removes all soft fouling

 Heat exchangers:

 A float switch event is when the

condensate tank water level is low.

Flash Type evaporation:

The color indicator in the acid powder denotes the following colors,

Dark Green, YELLOW, Light Green, Green

What do the colors mean

Dark Green = dry powder form

YELLOW = disolved and heated

Light green = acid is 85% consumed, very weak

Green = acid is 95% exhausted

When maintaining a heat exchanger, you must adhere to which of the following safety procedures?

A. Clean the plates with a fiber brush and clean water. (Clean the plate while attached to the frame if possible.)

B. Always wear rubber or plastic gloves, goggles or plastic face shield, rubber or plastic apron, and boots when using trisodium phosphate

C. Check for leaks using hydrostatic testing

D. Wipe the gasket areas dry on both sides of the plate and check to make sure that there is no debris in the gasket area

When cleaning the tube sheet and inside shell of a heat exchanger, use a stiff _____ brush or plastic scraper.

A. metallic

B. nonmetallic

C. wire

D. rotary-powered

When cleaning a plate-type heat exchanger, you should use caution when handling the plates because _____.

A. fingerprints will cause a chemical reaction with the trisodium phosphate

B. always use steel wool or a steel brush to ensure proper cleaning

C. the edges can be very sharp and may cause injury

D. coat the plates with light machine oil before reassembly

Which type of damage will usually result from current flow between dissimilar metals?

A. Mechanical damage

B. Erosion

C. Corrosion

D. Stress corrosion

What percentage of tubes becoming plugged in a tube type heat exchanger will cause the exchanger to function improperly?

A. 5%

B. 10%

C. 15%

D. 20%

Which of the following is NOT a purpose of an auxiliary boiler?

A. To provide heat for shipboard heating systems

B. To provide heat for the evaporators

C. To produce steam for the galley

D. To provide steam for propulsion

Two types of auxiliary boilers in use in the Coast Guard are _____.

A. watertube and tiretube

B. evaporative plate and steamtube

C. firetube and steamtube

D. saturation and condensate

The temperature at which water boils is called the boiling point or the _____.

A. flashpoint

B. upper explosive limit

C. condensation temperature

D. saturation temperature

What is the liquid called that results from saturated steam giving up its heat?

A. Saturate

B. Condensate

C. Distillate

D. Dew point

What component controls the start-up and shutdown sequences of an auxiliary boiler?

A. Burner unit

B. Ignition transformer

C. Flame safeguard control (FSC)

D. Tri-cock

Which of the following conditions is NOT generally a hazard associated with auxiliary boilers?

A. High pressures.

B. High temperatures

C. Hazards associated with fuel

D. Diffuser swirl

D. Diffuser swirl

How often should the auxiliary boiler feedwater supply system be tested?

A. Daily

B. Weekly

C. Monthly

D. Quarterly

The alkalinity test has been replaced by direct measurement of _____ on Johnson boilers.

A. chloride level

B. pH

C. feedwater temperature

D. titration

The Riley-Beaird flash type evaporator has _____ stages.

A. two

B. four

C. six

D. eight

The feedwater for the distilling plant is supplied from the sea and enters the system through a _____ sea chest.

A. pressure

B. vacuum

C. manual

D. suction

D. suction

The water level appears over halfway in the sight glasses that are mounted on the front of a flash type evaporator unit. This situation could be caused by a restricted flow of the feedwater between flash chambers or by _____.

A. faulty operation of the brine overboard pump through the overthrottling of the brine overboard discharge valve

B. faulty operation of the distillate pump discharge valve

C. faulty operation of the feedwater temperature regulator

D. an improperly installed distillate line

The temperature pilot to the feedwater temperature regulator should maintain a temperature of _____ degrees Fahrenheit.

A. 155 to 160

B. 165 to 170

C. 170 to 175

D. 175 to 180

When the steam feedwater heater shell pressure decreases from approximately 11 inches Hg (vacuum) to 0 psig, you should _____.

A. check the brine discharge for signs of overheating

B. perform a cleaning procedure

C. open the sea chest valve fully

D. increase the pressure throughout the system

What are the two basic types of OWS?

A. Coalescing and pressure

B. Vacuum and gravity pressure

C. Vacuum gravity and pressure

D. Replaceable and nonreplaceable

The natural ability of two dissimilar liquids to separate (e.g., the oil and water found in bilges or ballast tanks) is called the principle of _____.

A. coalescing

B. digressing

C. scattering

D. cohabitation

Which of the following is NOT a coalescing media that would improve the efficiency of oil removal?

A. Metal plates

B. Replaceable filters

C. Brush assemblies

D. Emulsified polycarbonate

D. Emulsified polycarbonate

What component of an OWS employs an optical system based on the principles of light scattering?

A. Solenoid valve

B. Oil content detector

C. HELI-SEP separator

D. Defective oil sensing probe

The "clean water inlet" and "clean water outlet" found in an OWS are what type of valve?

A. Self-seating foot valve

B. Remote sensing flood valve

C. Solenoid valve

D. Vacuum valve

Which statement BEST describes Pascal’s law?

A. Pressure that is applied to a confined liquid is transmitted in all directions and loses force when acting upon surfaces with greater area

B. Force that is applied to liquid is magnified in power in all directions and acts with a greater force on areas that are at right angles

C. Weight that is applied to a column of liquid modifies the motion of the liquid when the force is confined to surfaces that are at right angles to the weight

D. Pressure that is applied to a confined liquid is transmitted undiminished in all directions and acts with equal force on equal areas

D. Pressure that is applied to a confined liquid is transmitted undiminished in all directions and acts with equal force on equal areas

26. Which of the following is NOT a safety precaution/guideline that should be considered PRIOR to starting work on a hydraulic system?

A. Secure and tag out all systems before working on them IAW Equipment Tag-Out Procedures, COMDTINST 9077.1 (series)

B. Completely depressurize the section of the system being worked on, and if possible, remove hydraulic fluid to an approved storage container. To verify that a system is depressurized, check gauges installed in the system. If gauges are not present, slowly crack open fittings and check for pressure

C. DO NOT wear loose fitting clothing. These items can become caught in moving machinery

D. NEVER move a control valve in any direction as it will cause pressure to build up when the system is disconnecteded

D. NEVER move a control valve in any direction as it will cause pressure to build up when the system is disconnecteded

Which of the following is NOT a safety precaution that should be taken WHILE WORKING ON a hydraulic system?

A. Completely depressurize the section of the system being worked on, and if possible, remove hydraulic fluid to an approved storage container. To verify that a system is depressurized, check gauges installed in the system. If gauges are not present, slowly crack open fittings and check for pressure

B. NEVER work on a running system, except for minor pressure adjustments (e.g., setting the pressure relief valve)

C. Cover joints with flange shielding to prevent leaking fluid from spraying onto heat sources, electrical and electronic equipment, and personnel

D. Always follow proper casualty control procedures when correcting hydraulic leaks. NEVER attempt to repair leaks on operating machinery. If system cannot be secured immediately, report the leak and take precautions to prevent fire

Which situation may be a cause of a malfunctioning hydraulic system?

A. Presence of air in the system

B. Improper voltage supplied to the automatic spooler pressure regulator

C. Hydraulic fluid with a water content of 50 ppm

D. Use of a positive displacement pump in the system

A hydraulic system is found to have a fault that is described as "over-riding work load." How should you correct the this problem?

A. Lubricate the spooler valve

B. Adjust, repair, or replace the counterbalance valve

C. Replace cooler control valve

D. Change filters

Two types of filters commonly used in hydraulic systems are _____.

A. partial flow and full flow

B. full flow and proportional flow

C. proportional flow and restricted flow

D. bypass flow and full flow

Two types of strainers commonly used in hydraulic systems are _____.

A. paper and plastic

B. wire mesh and side disk

C. edge disk and fiber mesh

D. wire mesh and edge disk

D. wire mesh and edge disk

The PRIMARY indication that a filter element is clogged and needs renewing is _____.

A. a sudden drop in accumulator pressure

B. no pressure when pump stops running (when there was normal pressure when pump was running)

C. a pressure differential that exceeds a specific value

D. an external fluid leak

What are the two types of AC motors?

A. Induction and synchronous

B. Single-phase and poly-phase

C. Wound-rotor and squirrel cage

D. Single-phase and wound-rotor

Which type of AC motor is MOST widely used today?

A. Poly-phase wound-rotor

B. Single-phase induction

C. Poly-phase induction

D. Single-phase squirrel cage

What NEMA code is the MOST commonly found on the nameplate for AC induction motors?

A. "D"

B. "C"

C. "B"

D. "A"

Which of the following is NOT normally identified on a motor’s name plate?

A. Volts

B. Torque

C. Amps

D. Hertz

Which motor nameplate term identifies the rated full-load speed of a motor?

A. Horsepower

B. Hertz

C. Amps

D. Revolutions per minute

D. Revolutions per minute

Which directive contains a list of the electrical safety precautions pertaining to working on AC motors?

A. NEM, Chapter 302

B. COMDTINST M9000.1 (series)

C. NEM, Chapter 300

D. NSTM, Chapter 300

D. NSTM, Chapter 300