Deck 12: System Evacuation

Question 1

Quite often, technicians rely on their gauge manifolds to determine if a sufficient vacuum has been achieved. This __________ acceptable field practice.

A) is
B) is not

Answer 1

B

Question 2

The proper oil level in a vacuum pump should be:

A) above the top of the sight glass
B) below the bottom of the sight glass
C) in the middle of the sight glass
D) at the bottom of the sight glass

Answer 2

C

Question 3

When evacuating a system, the technician should __________ operate the compressor while the system is in a deep vacuum.

A) always
B) occasionally
C) never

Answer 3

C

Question 4

According to the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE), the minimum vacuum level in a system should be __________ microns.

A) 1,000
B) 2,000
C) 3,000
D) 5,000

Question 5

A perfect 30"Hg vacuum is, in reality, unobtainable. So when reference is made to a 30"Hg vacuum, we are actually referring to a vacuum of __________.

A) 25.4"Hg
B) 28.9"Hg
C) 29.29"Hg
D) 29.92"Hg

Question 6

At a gauge pressure of 28.9"Hg, the equivalent reading on a micron gauge is about __________ microns.

A) 24, 500
B) 25, 400
C) 42, 500
D) 54, 200

Question 7

During the evacuation process, __________of the system should be connected to the vacuum pump.

A) the high-pressure side
B) the low-pressure side
C) both the high- and low-pressure sides

Question 8

Vacuum pumps are intended to be used on systems that are at or below atmospheric pressure. The technician should avoid using them on systems that are at pressures over __________ psig.

A) 0
B) 196
C) 243
D) 270

Question 9

The presence of acid in the system can damage the __________ and lead to the premature __________ of the system. Acid can also eat away at the interior surfaces of the __________.

Question 10

Some manufacturers recommend draining the oil from the vacuum pump after each use to prevent pump __________.

A) contamination
B) corrosion
C) drainage
D) leakage

Question 11

The technician should never block the vacuum pump exhaust port because blocking this port can cause the __________ in the pump to reach unsafe levels.

A) ballast
B) gas
C) oil
D) pressure

Question 12

When the system is being evacuated and a vacuum is being pulled on the system, the readings on the gauge manifold will register values __________ 0 psig.

A) above
B) below
C) equivalent to

Question 13

In a vacuum of 29.92"Hg, the micron gauge will read approximately __________ microns.

A) 15
B) 25
C) 35
D) 52

Question 14

For most residential systems, a ____ cfm vacuum pump is adequate.

A) 3
B) 4
C) 5
D) 6

Question 15

How often should the vacuum pump oil be changed?

A) every 3 months of operation
B) every other time it is used
C) before each use
D) every 8 hours of operation

Question 16

If moisture is not removed from the system prior to startup, system damage can result, including such problems as __________ and __________.

Question 17

Freezing moisture in the system can lead to a multitude of problems. List four of these problems.

Question 18

Industry and Federal guidelines require that the vacuum level in an evacuated air conditioning system be measured in __________.

A) inches of mercury
B) cfm
C) microns
D) psig

Question 19

__________ will not change from a vapor to a liquid within the normal pressure ranges commonly found inside air conditioning and refrigeration systems.

A) Combustible gases
B) Condensable gases
C) Noncondensable gases
D) Noncondensate gases

Question 20

Noncondensable gases have a negative effect on system performance because, if not removed, they will migrate to the condenser coil. This leads to a number of problems. List six such problems.

Question 21

To speed the evacuation process, __________ can be added to the system. This will help boil off any liquid moisture into __________, which is much easier for the pump to remove. If this method is used, __________ should be heated to prevent moisture from vaporizing in one part of the system and condensing back to a liquid in another.

Question 22

When evacuating a system, the technician should use __________ or __________ hoses as synthetic hoses are __________ (they allow gases to penetrate)

Question 23

A __________ is made up of two rotary pumps where the outlet of one pump is the inlet of the second.

Question 24

List 10 features commonly found on vacuum pumps.

Question 25

The Schrader valves commonly found on system service valves create a restriction even when they are in the open position. __________ can be used to remove the Schrader pins for evacuation and to replace the pins after the proper vacuum has been achieved.

Question 26

Deep vacuum is the term used to describe a vacuum range between __________ and _________.