chapter 11 Flashcards
(30 cards)
The thermostat equipped with a coil-shaped bimetal element operating a mercury bulb switch has an operating range of between:
Select one:
A.
5°C and 28°C (41°F and 82°F)
B.
12°C and 30°C (54°F and 86°F)
C.
0°C and 20°C (32°F and 68°F)
D.
20°C and 42°C (68°F and 108°F)
E.
10°C and 32°C (50°F and 90°F)
E.
10°C and 32°C (50°F and 90°F)
When dealing with electrical controls transformer refers to:
Select one:
A.
A device consisting of a solenoid coil, which operates load carrying contacts when the coil is energized
B.
A term that refers to the normal electric supply voltage
C.
A term that refers to wiring or other electrical devices using 30 volts or less
D.
The electric switch configuration of a relay
E.
A device used to change AC voltage from one value to another
E.
A device used to change AC voltage from one value to another
One of the most important controls in a heating system is the:
Select one:
A.
Humidistat
B.
Operating control
C.
Pressurestat
D.
Aquastat
E.
Thermostat
E.
Thermostat
A three-way valve is a:
Select one:
A.
Single-seated valve
B.
Ball-seated valve
C.
Triple-seated valve
D.
Gate-seated valve
E.
Double-seated valve
E.
Double-seated valve
The sensing element of the _____ is liquid filled and the switch is actuated by the expansion and contraction of the liquid when there is a temperature change of the controlled medium.
Select one:
A.
Pressurestat
B.
Bimetal thermostat
C.
Humidistat
D.
Immersion thermostat or Aquastat
E.
Remote bulb thermostat
D.
Immersion thermostat or Aquastat
Using electricity for control purposes has the following advantages except:
Select one:
A.
The wiring is usually simple and easy to install.
B.
Single controller/actuator combinations are possible
C.
It is readily available.
D.
The signals received from sensing elements can be used to produce more than one electro-mechanical output.
E.
A source of compressed air is required
E.
A source of compressed air is required
When dealing with electrical controls low voltage refers to:
Select one:
A.
A term that refers to wiring or other electrical devices using 30 volts or less
B.
A term that refers to the normal electric supply voltage
C.
A device used to change AC voltage from one value to another
D.
The electric switch configuration of a relay
E.
A device consisting of a solenoid coil, which operates load carrying contacts when the coil is energized
A.
A term that refers to wiring or other electrical devices using 30 volts or less
In a typical electric control system in a warm air heating system the thermostat is referred to as the:
Select one:
A.
Controlled variable
B.
Final control element
C.
Set point
D.
Controller
E.
Manipulated variable
D.
Controller
The sensing element of a bimetal thermostat consists of a:
Select one:
A.
Bulb/capillary tube/bellows combination containing a volatile liquid
B.
Strip made up of two thin layers of different metals which expand at widely different rates
C.
Hygroscopic element
D.
Bourdon tube
E.
Diaphragm with sensing pressure on one side and a reference pressure on the other
B.
Strip made up of two thin layers of different metals which expand at widely different rates
When dealing with controls an actuator is a device:
Select one:
A.
That connects an actuator to a damper or control valve
B.
Used to control the flow of air in a duct or through a wall louvre
C.
Used to change AC voltage from one value to another
D.
Used to position dampers and control valves
E.
Used to control the flow of fluid or gas such as water, air, or steam
D.
Used to position dampers and control valves
Electrical contacts that complete circuits when a relay is energized are referred to as _____ contacts.
Select one:
A.
Normally closed (NC)
B.
Naturally Closed (NC)
C.
Normally open (NO)
D.
Not open (NO)
E.
Naturally open (NO)
C.
Normally open (NO)
The motor operator used with a motor-operated valve consists of a:
Select one:
A.
Reversible driving motor and reduction gears mounted in a sealed casing and completely submerged in oil
B.
Reversible driving motor and reduction gears mounted in a sealed casing and completely submerged in water
C.
Direct driving motor and reduction gears mounted in a sealed casing and completely submerged in water
D.
Reversible driving motor and reduction gears mounted in an open casing and completely submerged in oil
E.
Direct driving motor and reduction gears mounted in a sealed casing and completely submerged in oil
A.
Reversible driving motor and reduction gears mounted in a sealed casing and completely submerged in oil
Three-way valves can be used in hydronic heating systems for _____ service.
Select one:
A.
Agitating
B.
Pressure
C.
Diverting
D.
Coagulating
E.
Volume
C.
Diverting
Three-way valves can be used in hydronic heating systems for _____ service.
Select one:
A.
Coagulating
B.
Volume
C.
Agitating
D.
Pressure
E.
Mixing
E.
Mixing
Electrical contacts that complete electric circuits when a relay is de-energized are referred to as _____ contacts.
Select one:
A.
Naturally open (NO)
B.
Normally closed (NC)
C.
Naturally Closed (NC)
D.
Not open (NO)
E.
Normally open (NO)
B.
Normally closed (NC)
A capacitor type control motor has the rotor and gear train sealed in a housing partially filled with:
Select one:
A.
Oil
B.
Nitrogen
C.
Glycol
D.
Water
E.
Grease
A.
Oil
When dealing with controls a control valve is a device:
Select one:
A.
That connects an actuator to a damper or control valve
B.
Used to control the flow of fluid or gas such as water, air, or steam
C.
Used to position dampers and control valves
D.
Used to control the flow of air in a duct or through a wall louvre
E.
Used to change AC voltage from one value to another
B.
Used to control the flow of fluid or gas such as water, air, or steam
Electrical control systems usually employ a normal line voltage of:
Select one:
A.
12 or 24 volts DC
B.
12 or 24 volts AC
C.
120 or 240 volts AC
D.
240 or 600 volts AC
E.
120 or 240 volts DC
C.
120 or 240 volts AC
When dealing with controls a controller is a device:
Select one:
A.
Used to control the flow of fluid or gas such as water, air, or steam
B.
Which reacts to pressure, temperature, or humidity to provide two position, floating, or proportioning control of an actuator or relay
C.
Used to position dampers and control valves
D.
That connects an actuator to a damper or control valve
E.
Used to change AC voltage from one value to another
B.
Which reacts to pressure, temperature, or humidity to provide two position, floating, or proportioning control of an actuator or relay
Electrical control systems may use a low voltage of:
Select one:
A.
12 or 24 volts DC
B.
120 or 240 volts DC
C.
240 or 600 volts DC
D.
12 or 24 volts AC
E.
122 or 240 volts AC
D.
12 or 24 volts AC
The thermostat equipped with a coil-shaped bimetal element operating a mercury bulb switch is quite sensitive, having a temperature differential of less than:
Select one:
A.
1°C (1.8°F)
B.
2°C (3.6°F)
C.
5°C (9°F)
D.
10°C (18°F)
E.
3°C (5.4°F)
A.
1°C (1.8°F)
The duct thermostat is used to sense the air temperatures in:
Select one:
A.
Freezers
B.
Ducts and plenums
C.
Rooms
D.
Boilers
E.
Coolers
B.
Ducts and plenums
When dealing with controls a damper is a device:
Select one:
A.
Used to control the flow of fluid or gas such as water, air, or steam
B.
That connects an actuator to a damper or control valve
C.
Used to position dampers and control valves
D.
Used to change AC voltage from one value to another
E.
Used to control the flow of air in a duct or through a wall louvre
E.
Used to control the flow of air in a duct or through a wall louvre
The electric modulating thermostat uses a _____ to produce a varying output signal.
Select one:
A.
Sensing bulb
B.
Bimetal strip
C.
Variable potentiometer
D.
Bourdon tube
E.
Bellows
C.
Variable potentiometer
