Honeywell Pneumatics Exercise

Question 1

Name two ways of drying the air?

Answer 1

1. Refrigerated air dryers
2. desiccants

2. Dessicants

Question 2

What components are in the PRV/filter station?

Answer 2

1. filter
2. drain cock
3. PRV
4. tank
5. supply air gauges

Question 3

What type controller are the thermostats in a pneumatic system?

Answer 3

inherently modulating

Question 4

Typically, what is the main air pressure supply?

Answer 4

approximately 18psi

Question 5

What is the name of the line between the thermostat and the actuator?

Answer 5

branch

Question 6

What is the purpose of the bimetal in the thermostat?

Answer 6

as temp changes the strip will move allowing the flapper to release air or allow press to build up

Question 7

What are pneumatic relays used for?

Answer 7

to manipulate pneumatic control signal for sequence of operation

Question 8

What forces move the push rod open and closed?

Answer 8

open- air pressure

closed - spring

Question 9

What type of construction are the actuators?

Answer 9

rolling diaphragm

Question 10

Explain how a damper is considered normally open or normally closed?

Answer 10

if the actuator return spring drives the damper open or closed at 0psi

Question 11

What is another term used to describe normally open or normally closed?

Answer 11

fail position

Question 12

What position is the stem in a reverse acting valve when it is open?

Answer 12

stem is down

Question 13

What position is the stem in a direct acting valve when it is closed?

Answer 13

stem is down

Question 14

When a spring is added in a direct acting actuator, what position is the stem?

Answer 14

normally retracted stem

Question 15

When a spring is added in a reverse acting actuator what position is the stem?

Answer 15

normally extended stem

Question 16

What does the spring range determine?

Answer 16

start and stop of the valve stroke

Question 17

What is important to for the valve to close off 100%?

Answer 17

enough closing torque

Question 18

What does a valve positive positioner prevent?

Answer 18

eliminates disk float

Question 19

What can be added to use electricity to control the valve?

Answer 19

DDC controller

Question 20

What is better about a pneumatic actuator?

Answer 20

better torque

Question 21

What pressure is seen when the filter element needs to be replaced?

Answer 21

10psi

Question 22

What should be checked before calibrating a thermostat?

Answer 22

ensure you have enough main pressure, 18-20psi

Question 23

What does the bimetal respond to?

Answer 23

room temp

Question 24

What are the terminals labeled on a two pipe thermostat and what pipe on each terminal?

Answer 24

M - main

B- branch

Question 25

By bleeding of air, how does this affect the actuator?

Answer 25

causes the actuator to modulate

Question 26

Where is the resistor located in a one pipe thermostat?

Answer 26

internally inside the thermostat

Question 27

Where is the restrictor located in a single pipe installation?

Answer 27

in the main line before the thermostat

Question 28

What material is used for piping air lines?

Answer 28

old days copper modern plastic tube

Question 29

How does a low capacity thermostat thermostat effect the actuator?

Answer 29

same power but slower reaction time

Question 30

What is the throttling range?

Answer 30

is the change in degrees that will cause the valve/damper to go from full open to full close

Question 31

What is set point?

Answer 31

desired temp

Question 32

What is control point?

Answer 32

current room or space temp

Question 33

What its the difference between the set point and control point called?

Answer 33

offset

Question 34

If a thermostat has a throttling range of 4 degrees and the set point is 68 F. What position will the valve be in at 66F in cooling mode (chilled water)?

Answer 34

fully closed

Question 35

If a thermostat has a throttling range of 4 degrees and the set point is 68F. What position will the valve be in at 74F in cooling mode? (chilled water)

Answer 35

fully open

Question 36

If a thermostat has a throttling range of 3 degrees and the set point is 72F. What position will the valve be in at 74F in cooling mode? (hot water)

Answer 36

fully open

Question 37

What causes the room temperature to drop below the thermostat set point?

Answer 37

heat loss, if the heat loss is greater than the heat supplied

Question 38

How does proportional control compensate for high heat loss?

Answer 38

opens the valve more to allow more heat to enter the space

Question 39

What will a small throttling range cause?

Answer 39

the system to hunt causing under and overshoots

Question 40

Where is throttling range adjusted?

Answer 40

At the thermostat. True for DDC systems as well

Question 41

Why is it important to check the calibration of a thermostat?

Answer 41

To maintain the temp at the correct setting

Question 42

How do you calibrate your temperature measuring device?

Answer 42

Ice or boiling water

Question 43

What is the recommended main air pressure?

Answer 43

17-20psig

Question 44

What should you check for if the main air pressure is low?

Answer 44

leaks, kinks, air blockage, regulator set too low

Question 45

What should be done before you leave after calibrating a thermostat?

Answer 45

ensure actuator is responding then set T-stat to normal room setting

Question 46

What is a two temperature thermostat used for?

Answer 46

two temperature set points, day and night or heating and cooling

Question 47

How does the thermostat switch from day to night?

Answer 47

by changing main air pressure from high to low | set back

Question 48

What type of PRV is required and what other component is needed?

Answer 48

dual pressure PRV and electric pneumatic relay

Question 49

What components are used if using the alternate PRV method?

Answer 49

two PRV's, an E/P relay which diverts air from A to C high press or B to C low press

Question 50

How many bimetal strips and flappers are in this thermostat?

Answer 50

two of each and both must be calibrated

Question 51

When is it recommended to check the calibration of a thermostat?

Answer 51

yearly scheduled maintenance, maybe twice a year for heating and cooling

Question 52

Why is it important to check the calibration of a thermostat?

Answer 52

check if they are measuring the proper temperature, check for wear and tear, check valves

Question 53

What type of stat are combo coils used in?

Answer 53

heating and cooling

Question 54

Name 6 types of relays in a pneumatic system?

Answer 54

1. capacity relay 2. variable pressure switch 3. air flow relays & controllers 4. reversing relay 5. pneumatic to electric relay 6. sequencing/ratio relay

Question 55

Name 8 port designations

Answer 55

1. main 2. branch 3. input 4. n.o 5. common 6. n.c

Question 56

in a heat cool thermostat what does the thermostat do when switching between heating and cooling?

Answer 56

reverse acting for cooling and direct acting in heating

Question 57

What is an EP valve and what is it's function?

Answer 57

electric to pneumatic, used to divert air

Question 58

What voltages are used in a E/PT?

Answer 58

2-10 volts DC

Question 59

How does the PE relay work?

Answer 59

as the pressure in the bellows change it will move a lever causing a switch to open or close

Question 60

Name uses of a P/E?

Answer 60

turn on or off pumps, fan coils, day night control, electric heaters

Question 61

What does a selector relay do?

Answer 61

can allow the higher or lower of the two pressures to pass through

Question 62

How can a selector be used in a zoning system?

Answer 62

by selecting the highest signal to determine heating or cooling

Question 63

How many thermostats can be attached to a RP913A load analyzer?

Answer 63

up to 7 inputs

Question 64

What device should be added (checked on an analyzer?

Answer 64

an air filter, 1psi differential you must replace

Question 65

Explain the operation of a switching relay?

Answer 65

as pressure changes in the pilot port, air will move from common port to normally connected or disconnected port

Question 66

What is a capacity relay used for?

Answer 66

increase strength of an input signal

Question 67

Explain minimum position?

Answer 67

minimum a valve or damper will close without closing 100%

Question 68

Explain maximum position?

Answer 68

maximum a valve or damper will open without opening 100%

Question 69

What application would a minimum position be applied?

Answer 69

fresh air dampers so there is always a certain amount of fresh air entering the building

Question 70

What controller an be used in a VAV box to control air flow?

Answer 70

velocity controller

Question 71

When are summer/winter thermostats used?

Answer 71

when reverse acting for heating and direct acting for cooling

Question 72

When is the electric heat strip used and why?

Answer 72

only during summer to temper chilled air and not in winter because of high operating costs