Monday Test Flashcards
Pass
1
Q
How can ice be removed from a sight glass
A
with alcohol spray
2
Q
What must be done with badly corroded relief valves
A
replace them
3
Q
Where can you find the allowable test pressure on a system
A
Unit Data Plate
4
Q
Can Oxygen be used to check for leaks? If not why not?
A
No. Oxygen in the presence of oil under high pressure can be explosive
5
Q
What is the likely result of heating a recovery cylinder with an open flame
A
The refrigerant inside will decompose into a toxic material, venting of refrigerant into the atmosphere or the tank may explore
6
Q
What is the primary purpose of disposable cylinders?
A
For virgin refrigerants from the manufacturer
7
Q
To what internal pressure should a disposable cylinder be reduced to for disposal?
A
0 PSIG
8
Q
Should you ever use a disposable cylinder for refrigerant recovery
A
No
9
Q
To dispose of a cylinder you should be sure all refrigerant is recovered and the cylinder is no longer usable. What else?
A
Puncture the container before disposal
10
Q
For safety, refrigerant cylinders should not be rusted or damaged and always properly color coded. What additional step should also be taken with these cylinders?
A
Properly secured at all times
11
Q
What is the proper color code for recovery cylinders?
A
Grey with a yellow top
12
Q
What is the maximum percent by weight that a cylinder may be filled
A
80%
13
Q
What can happen if a cylinder is overfilled
A
Hydrostatic pressure could cause the cylinder to explode
14
Q
List 3 methods for measuring the fill level of a recovery cylinder?
A
Floats, thermistor type sensors, weighting scales
15
Q
How often must reusable cylinder be hydrostatically tested?
A
every 5 years
16
Q
Why must only refillable cylinders be used for transport
A
Federal code of regulations title 49
17
Q
The clean air act phases out CFC/HCFC production and prohibits venting. What else does it require
A
Standards to be set for recovery of all refrigerants prior to appliance service and disposal
18
Q
Falsifying or failing to keep required records, failing to reach required evacuation levels and knowinly releasing CFC or HCFC refrigerants are violations of the Clean Air Act. What activity with a substitute refrigerant is also a violation?
A
KNOWINGLY venting CFC and HCFC and their substances.
19
Q
Which refrigerants must be recovered prior to opening a system?
A
All refrigerants as of November 15 1995
20
Q
What releases of a CFC and HCFC are violations of the Clean Air Act?
A
Any KNOWINGLY vented refrigerants
21
Q
On what date did it become illegal to vent CFC and HCFC
A
July 1 1992
22
Q
Which appliances are covered by Section 608
A
Any device which contains and uses a class 1 or class 2 substances as a refrigerants and is used for household or commercial purposes.
23
Q
What is the primary reason the EPA requires a service aperture or process stuff on all appliances
A
For adding or removing refrigerant from the appliance
24
Q
The Montreal Protocol calls for the regulation of what chemicals
A
Ozone depleting compounds CFC HCFC and Halons
25
On what date was the importation and production of all CFC phased out?
In the US December 31 1995
26
Where will we get replacements?
Through recovery of existing refrigerants
27
What steps are called for by the Clean Air Act
Taxes on production and use, standards set for the recovery of refrigerants
28
What is prohibited by the Clean Air Act
Venting
29
Does Atmospheric Ozone help or hurt the work of the earths protective shield
It helps
30
What chemical in the statosphere tells us ozone depletion is occurring?
Chlorine-monoxide
31
How do we know the chlorine in the statosphere is coming from CFC?
the increase in chlorine and flourine matches the emmissions of CFC
32
How do we know CFC get to the statosphere
from high altitude air sampling measurements
33
What role does the ozone layer play in protecting the earth?
it blocks much of the harmful ultraviolet radiation UV-B
34
What are the effects from increase UV radiation
Skin cancer, cataracts, lowered human immunity
35
What are the effects of increased UV radiation on the environment?
timber growth is reduced, crop yields lowered, marine life and food chain are impaired.
36
What is the Montreal Protocol
A treaty that called for the reduction of production of CFCs
37
What is a ternary blend?
a blend of 3 different refrigerants
38
How should systems using blended refrigerants be charged?
in liquid for into the high side of the system
39
in there a drop in refrigerants for CFC-12
No
40
How do you leak check HFC134a system with a partial charge
recover the remaining refrigerant and pressurize with nitrogen add r22 so you can use a HCFC leak detector
41
What is the preferred oil to be used with HFC-134a
Ployolester
42
Can ester based oils be mixed with other oils
No
43
What lubricant is recommended for use with a ternary blend?
For HCFC Alkylbenze for HFC Ployolester or ester oil
44
Safety and butyl lined glves should be worn for what procedure
When operating recovery or recycling devices and when handling and refilling refrigerants cylinder
45
What is HFC
A fluorocarcon that contains no chlorine
46
Which refrigerants are HFC's
R134a. 404a, 407C, 410a
47
What is the ODP of HFC
Zero
48
Which refrigerant have high ODP
CFC
49
Which refrigerants have low ODP
HFCF and HFC
50
Does R500 have a CFC
Yes
51
What precautions should be taken when recovering refrigerant from a system with multiple service valves
Insure that liquid is not trapped between service valves
52
What is different about any leaks in systems charged with a blended refrigerant?
Because they are blended the ingredients will leak at different rates
53
What purpose is served by heating a system during evacuation
to speed up moisture removal
54
What is the result of over evacuating a system
no damage will be done
55
When measuring the vacuum of a system being evacuated the system must be isolated. What must be done to the vacuum pump?
Valve it off and turn it off
56
How much ozone can chlorine atom destroy
100,000
57
What refrigerants are CFCs
R11,12,113,114
58
What refrigerants are HCFC
R22 R123
59
What is a material safety data sheet
a sheet that states the safety ratings and precautions to be taken for use and handling of chemicals
60
What safety classification within the ASHRAE standard is most safe
A1
61
What is caused by inhaling of refrigerant vapors
heart irregularities or Asphyxia
62
What is the major cause of death involving refrigerants
Oxygen deprivation
63
What breathing problems can be caused by CFC12
Asphyxia
64
What is the preferred instrument for detecting small leaks
Electronic leak detector and Ultrasonic detector
65
When may a technician recover only 80% of the refrigerant in a small appliance?
In a system dependent recovery with a non operating compressor?
66
May a technician use a passive recovery machine for recovery from a domestic refrigerator?
Yes
67
What requirements are placed on recovery machines built after November 15 1993?
Must be able to recover 80% if compressor is inoperative or 90% if its working and must be EPA certified
68
When using a recovery machine made after November 15 1993 what percentage of the refrigerant must be recovered in a household refrigerator with and without an operational compressor
90%/80%
69
What must be affixed to a refrigerant cylinder prior to its shipment to a reclaimer?
DOT classification tag
70
What is the purpose of a DOT classification tag
its for transportation purposes
71
What is the EPA definition of a small appliance
charged at factory with 5lbs of refrigerant or less
72
Is it required to repair leaks in a small appliance?
No but recommended
73
What service aperture may be used on a small appliance
access tubes or process tubes
74
On what material are piercing valves used?
copper and aluminum lines
75
What should be done to a schrader valve after it is installed on a charged system?
capped off after any service procedure
76
Why should solder-less type piercing valves be removed after completion of repairs?
to prevent leaks
77
What are the critical maintenance checks done to a schrader valve
periodically checked for leaks and replaced if damaged
78
What do you do if oil is contaminated
tubing flushing
79
Why do large refrigerant leaks cause suffocation?
refrigerant will replace air in the confined space leading to possible oxygen starvation
80
How should you access the system and should you run the compressor when using a system dependent (passive) recovery on a refrigerator with an operable compressor
access the high side and run the compressor
81
What is the purpose of a compressor heater
to reduce the amount of refrigerant in the lubricating oil
82
What is the preffered method of leak checking a built up system prior to charging?
bubble solution
83
Who sets the regulations for recovery machines?
EPA
84
What is a self contained recovery machines
A recovery machine that has its own compressor to pump refrigerant out of the system
85
HCFC123a is a
low pressure refrigerant
86
CFC12
high pressure refrigerant
87
What are the typical ranges of pressure in a manifold
0-500 on high side and 0-350 low side and 0-30hg
88
According to ASHRAE Standards 15 what is the standard for refrigerant concentration for a machine room that must not be exceeded without activating an alarm and starting ventilation in the machine room
TLV TWA
89
List 4 safety procedures that should be followed when working with liquid low pressure refrigerant
Refrigerant sensor, avoid siphoning refrigerant by mouth, wear butyl lined gloves and safety glasses
90
what is the toxicity and flammability rating of HCFC-123 per ASHREA standard 34
B1
91
Device to prevent venting and loss in REFRG
Low loss fitting (Shut off valve)
92
What is the primary purpose of using hand valves or self sealing hoses hen using a gauge set
to prevent loss of refrigeration
93
Which refrigerants must be recovered according to 608 EPA
CFC, HCFC, HFC
94
The replacement refrigerant NOT DROP IN for CFC-12 in household refrigerators is
HFC-134a
95
When doing a non condensables check, a recovery cylinder should stabilize in temperature before any readings are taken why?
to find the correct pressure for that temperature on a T/P Chart
96
What is a system dependent recovery machine
One that relies on the compressor of the system being serviced or the pressure of the refrigerant to pump the refrigerant into the recovery drum
97
Describe a system dependant passive recovery process for small appliances
evacuate and cool recovery cylinder and connect to high and low side and use low pressure or a vacuum on tank
98
What 2 conditions require that you access both high and low side of the system for refrigerant recovery
when compressor is broken or you need to adjust required recovery levels
99
What is the initial charging method of a system when the charge is specified at 70lbs
charged in liquid state
100
Where is the accumulator located in a refrigeration system
on the suction line before the compressor
101
To prevent freezing of any moisture in a CFC-12 system vapor should first be charged to what level
33psig
102
What leak rates is permissible on industrial and process refrigeration
as of June 14 1993 a leak rate of 35% or more on equipment with 50lbs or charge or more must be repaired. Less than 35 is allowed
103
What leak rates is ok on equipment other than industrial or process equipment that contains more than 50lbs of refrigerant
Less than 15% a year
104
Why must water be circulated through a chiller during refrigeration recovery
To prevent freezeup of the water as pressure is reduced on the refrigerant
105
What is the lowest access valve on a low pressure chiller
The evaporator charging valve
106
Where is a centrifugal chiller rupture disk attached
at the evaporator
107
What is the typical pressure setting for a low pressure chiller rupture disk
15 PSIG
108
How is a chiller typically charged
Liquid through the evaporator charging valve
109
What minimum saturation temperature needs to be achieved before liquid is charged into a chiller
Above freezing typically 36f
110
To prevent freezing of water when charging a chiller, what pressure should be reached with vapor before using a liquid CFC-11
16.9 inches of Mercury
111
What could result from liquid refrigerant being charged into a chiller that is holding a 29.9 Inches of Mercury vacuum
Can cause system water to freeze
112
What function is served by a purge unit on a chiller
to reduce the effects of contamination and to purge non condensables.
113
What is the most likely cause of air leaks into a chiller refrigerated circuit
Gaskets and fittings
114
How is a purge unit connected on a low pressure chiller
the inlet of the purge unit is typically connected to the top of the condenser
115
Where is the suction of a purge unit connected
the inlet of the purge unit is typically connected to the top of the condenser
116
What is a high effeciency purge unit
it removes non-condensables that contain low percentages of refrigerant. This adds to the valve of the purge drum in refrigerant containment
117
Shaft seals on an open type compressor are susceptible to what failures
refrigerant leaks
118
What rise in a vacuum is permitted under ASHRAE 3-1990
after 12 hours no more than 2.5mm of Mercury
119
List two steps to reduce the run time of a purge unit on a chiller
regular leak checks and repair any leaks
120
Why should the water side of the evaporator and condenser be drained before recovering refrigerant from a chiller suspected of having a tube leak
to prevent moisture from being drawn into the refrigerant circuit
121
If a purge unit is operating excessively it usually will mean?
Leaks
122
What condition would cause continuous excessive moisture collection in the purge unit of a low pressure refrigeration system?
Leaks between the refrigerant circuit and the water circuit
123
Why would oil be warmed prior to removal from a low pressure chiller
to vaporize any liquid refrigerant that might be trapped in the oil
124
Is recovery of a refrigerant from a low pressure appliance typically started with liquid or vapor
Liquid removal
125
Purge unit work best when they are not needed. How can purge unit operating time be reduced
regular leak checks and repair on a regular schedule
126
Max pressure for leak checking a low pressure chiller
10PSIG on low pressure equipment that uses rupture disk
127
What is the preffered method of leak checking a chraged low pressure chiller?
by increasing the refrigerant pressure using an external heat source or running hot water through the chiller tubes not to exceed 10 PSIG
128
Where would you check for leaks between a chiller refrigerant tube and the water box
the chiller barrel can be emptied of all water and a leak check made at drain valve with water off. If tubes require leak check the check can be made with a hydrostatic tube test kit
129
What is a hydrostatic tube test kit used for
to check for leaks in a chiller tubes
130
What leaks rate is ok on industrial and process refrigeration
35% or more fix less than 35 is cool
131
Before using a recovery unit the tech should check service valve position and check the recovery unit oil level. What additional steps must be taken
All selenoid valves should be open
132
What can cause recovery equipment with a hermetic compressor to overheat when drawing a deep vacuum
no airflow over the compressor body or no suction gas flow over internal motors or both
133
What is the reason for not operating a hermetic compressor while in a deep vacuum
to prevent overheating
134
What is the reason for not starting a reciprocating compressor with its discharge service valve closed
prevent overheating
135
When can a "system dependent" recovery device be used
on small appliance as long as the recovery device meets EPA standards and the tech adheres to the servicing procedures specified for the recovery equipment. Cannot be used on a system with more than 15lbs refrigerant charge
136
What vacuum level must you reach when recovering from a system with 38 pounds of R502 using a recovery machine made in 1995
10 inches of Hg
137
In order to recover from a system with parallel compressors the individual compressors must be isolated why
it isolates the refrigerant that must be recovered from the rest of the system
138
Which refrigerants require an equipment monitor
all refrigerants
139
How should you pressurize an idle low pressure chiller to prevent air accumulation
Slightly above atmospheric pressure
140
Prior to making a major repair what vacuum level must you pull when using recovery equipment made in 1996 on a unit with 215lbs of CFC-12
15 inches of mercury
141
Under what circumstances may a tech recover the CFC refrigerant in an appliance to atmostpheric pressure only
leak or if it would contaminate the refrigerant
142
What is the water source for a condensing coil on a water cooled recovery machine
Municipal water tap
143
Where is the connection made for the water supply used on a water cooled recovery unit
local water supply
144
What should be the max pressure on the discharge of a recovery machine for low press systems
10psig since rupture disk bust at 15
145
What should be done with the water pumps during a recovery from a low pressure chiller
turn the water pump on
146
what recovery vacuum meet for appliance made in 1992
25Hg
147
To ship recovered refrigerant you must label the container and complete all necessary paperwork. What else
Send it in a DOT approved cylinder
148
What are piercings valves used for
to allow access to the sealed system for recovery
149
What does backseating a valve mean
allows flow through the main line while closing the access point
150
What will non condensables do to the pressure in refrigerant circuit
increase discharge pressure
151
Where is a receiver typically installed on a system
At the outlet of the condenser
152
Before enter an area of a large leak of refrigerant what apparatus must be worn
self contained breathing aparatus
153
What should be done if a large leak occurs and no breathing apparatus avail
ventilate and leave
