rmo 2018

Convert -34 degrees Celsius to Fahrenheit?

(-34×1.8)=-61.2+32=-29°F

Convert the vacuum pressure of 28"hg to absolute pressure(PSIA)?

(30-hg(28))÷2= 1 PSIA

Covert 87 degrees Fahrenheit to Celsius?

(87-32)=55÷1.8=30.5°C

Fahrenheit to Celsius?

(F-32)÷1.8

Convert a barometric pressure of 28"Hg to absolute pressure(PSIA)?

.491×28"Hg= 13.75 PSIA

What pressure Doesn't express a perfect vacuum?

0 psig

What are the known gauge sizes?

1-1/2" to 10"

If a compound gauge has a reading of 10 inches of mercury (hg) what is an equal pressure?

10 pounds absolute

Convert 10 psig into PSIA?

10psig + 14.7= 24.7 PSIA

Convert 115 degrees Celsius to Fahrenheit?

115×1.8=207+32=239°F

1 LB of Ice?

144 BTU'S

A barometer has a pressure reading of 29.40"hg. If The pressure increased to 34.4"hg what will be the pressure in absolute value?

17 psig

If the outside has dropped by 10°C the temperature drop in °F will be?

18

If you add 1 BTU to 1 lb of water it will increase by 1°F, If you add 10 BTUS to 10lbs of water it will increase by?

1°F (SPECIFIC HEAT)

What would be the heat transfer rate of a 30 ton refrigeration system?

200×30=360000 BTUs/min

Convert 26 PSIA into psig?

26 PSIA - 14.7(15)= 11 psig

2000 LBS of Ice?

288,000 BTU'S

One Ton of refrigeration is equal to?

288,000 BTUs/24hr 12,000 BTUs/60min 200 BTUs/60secs

What Is not equivalent to atmospheric pressure?

29.9 inches of vacuum

In Addition to monitoring operating pressures what else does the gauge manifold do?

Adds or removes refrigerant

What Color will red litmus paper show if ammonia is present?

Blue (ABR)

Dye Detection?

Bromothymol Blue turns yellow if CO2 Is present (CBY) Nessler's Solution turns yellow if Ammonia is present (AyNes) Red Litmus paper turns blue is ammonia is present (ABR)

The Relationship that is observed when a gas its maintained at a constant pressure while the volume of the gas varies in direct proportion with the change in the absolute temperature of the gas?

CHARLES LAW

What Is r-744?

CO2

What Refrigerant sublimates?

CO2

Which refrigerants operation pressure exceeds 1000 psig?

CO2 (r-744)

3 Methods of heat transfer?

CONDUCTION CONVECTION RADIATION

What Is r-744?

Co2 Discharge Pressure @86°F = 1031 psig Critical Temperature = 87.8°F Detected By Soapy water Bromothymol Blue

Which Form of heat transfer requires physical contact?

Conduction

288,000 btu/24-hr?

Cooling capacity in 24hrs/per day

12,000 btu/hr?

Cooling capacity in 60mins/per hour

200 btu/min?

Cooling capacity in 60secs/per minute

Celsius to Fahrenheit?

C×1.8(+32)

The Total pressure of a combined mixture of gasses is the sum of the pressure of each of the constituent gases?

DALTON'S LAW

What Effect on moving to a higher elevation have on barometric pressure readings?

DECREASED PRESSURE

What Color will a halide torches flame show if a strong leak is detected?

Dark blue

What Is Ashrae 34?

Designation And safety classification of refrigerant

What Is atmospheric pressure?

Force That is exerted by the gases and vapor that make up our atmosphere

What Is r-11?

Freon 11 non toxic/flammable colorless and odorless Detected By halide torch

What Is r-12

Freon 12 Boiling Point= -21.4°F lbs/mins/tons = 3.9 Non Toxic/flammable Colorless/Odorless Detected by halide torch

What is r-22?

Freon 22 Bolling Point = -41.4°F Color Is green Non Toxic/flammable colorless and odorless

New York city code refrigerants classifications?

Group 1 Non Toxic/Non Flammable Co2, r-11,r-12,r-21,r-22 Group 2 Toxic Ammonia, Sulphur Dioxide,Dichloroethylene, Methyl Chloride,Ethyl Chloride, Methyl Flormate Group 3 Flammable (Explosive) Propane, Butane, Isobutene, Ethane, Ethylene

latent heat of vaporization?

Heat ADDED to change the state of a substance without change in temperature EXAMPLE WATER TO STEAM

Superheat?

Heat ADDED to steam or refrigerant to raise temperature above its boiling point

Latent heat of condensation?

Heat that is REMOVED to change the state of a substance without a change in temperature EXAMPLE STEAM TO WATER

Sensible heat?

Heat that's associated with a CHANGE in temperature

Latent heat?

Heat that's associated with a change in state

latent heat of fusion?

Heat that's needed to change the state of the substance without changing the temperature example ice to water/water to ice

Conduction?

Heat transfer through direct contact EX If One end of the metal bar is heated the other end soon warms up

Radiation?

Heat transfer through space by shining Just like light is radiated EX The Suns rays radiate heat and warm us

Convection?

Heat transfer through the air EX Air blowing over q Product and back to Cooling coil Transfers heat from the product Via CONVECTION

Ashrae Refrigeration Code?

High flammability/low toxicity= A3 High flammability/high toxicity= B3 Low Flammability/low toxicity= A2 Low flammability/High Toxicity= B2 No Flammability/low toxicity= A1 No Flammability/High toxicity= B1

The Unit of vacuum on a compound gauge is?

Inches Of Mercury

Halide Torch?

Instrument That detects Freon leaks by color Pale blue/No Leak Green/Small Leak Dark Blue/Big Leak Yellow/Restriction In line

What is a gauge manifold?

Instrument used by service mechanics and operating engineers to determine both the high and low side pressures in a refrigeration system

Which of the following best describes the specific heat of water?

It is high at low temperatures and low at high temperatures

How Would you detect leaks in CO2?

Keep The plant in operation and coat the fittings with soapy water

What is needed to change the state of a substance?

Latent Heat (hidden heat)

Which process must be preformed in order to change water which is at a temperature of 32°F into ice at 32°F?

Latent heat of fusion

What Refrigerant is r-40?

Methyl Chloride

What Is r-40?

Methyl Chloride Cannot Be used with aluminum zinc and magnesium

Qualities desired in a good refrigerant?

No Effect of metal No Effect of oil non toxic and poisoness Non Flammable cheap and easy to find leaks etc

Refrigerant Stored in a machinery room?

No more then 20% of the normal refrigerant charged No More then 300lbs of refrigerant Only In Interstate commerce commission approved storage containers

What trait best describes r-22?

Odorless/Colorless

Convert barometric pressure to psia?

PSIA = "Hg × .491

Convert vacuum pressure to PSIA?

PSIA = (30 - "Hg/vac) ÷ 2

Convert Psig to Psia?

PSIA = psig + 14.7 EX 10psig + 14.7= 24.7 PSIA

What Is considered absolute values in units of pressure?

PSIA and "Hg (barometric)

What are the units of pressure?

PSIG "pounds per square inch gauge"(Above atmospheric pressure) 0 PSIG Hg "inches of mercury" vacuum gauge (below atmospheric pressure) (0 "Hg/vac) PSIA "Pounds per square inch absolute" perfect vaccum AND atmospheric pressure (14.7 PSIA) Barometric pressure Hg/absolute (29.92 "Hg/abs)

How Would you determine that a thermometer was indicating correct temperature?

Place it in an open container of boiling water

What Are the units of pressure on a compound gauge?

Pounds per square inch above atmospheric pressure and inches of vacuum below atmospheric pressure

Convert PSIA to psig?

Psig = PSIA - 14.7 EX 24.7PSIA - 14.7= 10

chapter 3

REFRIGERANTS

What is refrigeration?

Refrigeration is the removal of heat from an object or mass

What are the three states of matter?

Solid liquid and gas

If 1 pound of water is at a temperature of 32°F how many BTUs must be removed in order to create a block of ice at 17°F?

Specific heat of ice=.5 32-17=15°F 15×7.5=151.5 BTUs also 144+7.5=151.5

When latent heat is added or removed from a substance which of the following remains constant?

Temperature

Specific heat can be defined as?

The Quantity of heat needed to raise 1 lb of substance to 1°F

What is the specific heat of a substance?

The number of BTUs required to raise one pound of water to 1°F

Dalton's Law?

The total pressure of a mixture of gases is the sum of the individual pressures

Charles Law?

There Is a direct relationship between the pressure temperature and volume of a vapor or gas

What instrument is used to measure sensible heat?

Thermometer

What type of gauge should be used when a systems operating pressure will not exceed atmospheric pressure?

Vacuum Gauge

What is r-718?

Water

Which Refrigerant is r-718?

Water

Sublimation?

When a substance changes from a solid to a vapor without Passing the liquid State EX co2 DRY ICE

What Color will Nessler's solution turn if ammonia leaked into the brine solution?

Yellow (AYNESS)

Bromothymol blue is used to detect carbon dioxide leaks which color shows the presence of CO2?

Yellow (CBY)

pressure

pressure

What expresses the greater value of pressure?

5 psig

5lbs of water is at a temperature of 50°F how many BTUs must be removed in order to freeze the entire quantity?

50°F-32°F= 18°F specific heat +18°F=18 btUS 144 + 18 BTU'S= 162 BTUS 162×5=81O BTUS

One psi is equal to?

6,890 pascal or 6.890 kpa

Convert 1 psi into kpa?

6.894 (kpa)

The Metric unit for barometric pressure expressed in millimeters of mercury is "mmHg" what is the atmospheric pressure 29.92hg in mmHg?

760 mmhg

One of the disadvantages of using carbon dioxide is its low critical temperature. what is it?

87°F

How many BTUs must be added to vaporize the entire quantity of water?

970 BTUs

What Is r-717?

Ammonia Boiling Point= -28°F lbs/min/tons = .5 Detected with Nessler's solution/Red litmus paper cannot be used with Copper metal or brass

What Can be said for the operating pressures between ammonia and r-12?

Ammonia Is higher

The refrigeration process is made possible by?

The boiling of Refrigerant