Bas Flashcards

1
Q

Two pipe controllers receive and output how much psi

A

Receive 20 psi and output 0 - 20 psi

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2
Q

Two pipe controllers usually have what as part of their assembly

A

Temperature/humidity sensor

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3
Q

What are the 3 connections of a three pipe controller and their pressures

A

Supply of 20 psi, branch of 0 - 20 psi, and a sensor of 3 - 20 psi

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4
Q

Where are two pipe and three pipe controllers usually located.

A

Two pipe controllers usually on the wall
Three pipe usually in a secure cabinet

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5
Q

When selecting a pneumatic sensor what should you consider

A

The sensitivity and type of sensor for the appropriate medium

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6
Q

What are the 2 sections of pneumatically controlled devices?

A

The actuator and the final control devices

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7
Q

Electric to pneumatic solenoids have what ports

A

Pressure signal in and out and an exhaust

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8
Q

What are the 3 types of BAS system designs

A

1.Centralized supervisory
2. Centralized direct digital
3. Distributed direct digital

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9
Q

What’s variable frequency drive

A

Adjusts motor speeds through analog signal from the CPU

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10
Q

How else would you refer to the operator interface?

A

Head end/front end

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11
Q

What is used to adjust the throttling range of a two pipe controller?

A

Sensitivity slider

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12
Q

Pressure relief valve

A

Relieves pressure up to 120 psi

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13
Q

Blow down valve

A

Removes condensation from the receiver

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14
Q

Wet bulb temperature measures what type of heat and is related to what type of heat

A

Measures sensible heat as a result of latent heat changes

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15
Q

The higher the vapour pressure, the _ the rate of evaporation and the _ the rate of sublimation

A

Slower evap, slower sublimation

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16
Q

2 ways of expressing relative humidity

A
  1. Percentage of moisture in the air vs how much it can hold
  2. Percentage of water vapour vs water vapour pressure
17
Q

How’s humidity ratio expressed

A

Amount of moisture in any volume of air

18
Q

What’s the prefered RH at 68°F vs 80°F

A

60% at 68°F and 20% at 80°F

19
Q

How many grains are in 1lb of water

A

7000

20
Q

Specific volume vs specific density

A

SV: cuft/lb SD: lb/cuft

21
Q

What’s NTP and it’s conditions
(Temp, pressure, density, volume, specific heat)

A

68°F, 14.7psi, density: 0.075lb/ft3, volume: 13.33ft3/lb, specific heat: 0.24Btu/lb•°R

22
Q

Mass flow rate

A

Determines how much heat is flowing
lb/min

23
Q

MERV ratings

A

Basic resi = 1-4
Good resi/basic com = 5-9
Best resi/good com = 10-14
Hospital = 15-17
Clean rooms = 18-20

24
Q

Pitot tubes measure what pressures

A

Static and total pressure

25
Q

Anemometers 2 types

A
  1. Velometer
  2. Thermal and vane
26
Q

Barometers reads how much air flow

A

0 - 2000cfm

27
Q

How to start calculating airflow

A

• determine cfm (balometer) or
• measure velocity pressure (pitot tube) or
• measure velocity (anemometers)

28
Q

Velometer measures

A

Velocity

29
Q

How do you do duct traverse

A

For ⏹️: divide duct by 12-64, <6” apart rounded up
For ⭕: take readings in ➕ avoiding the center.

30
Q

What are the capacity ranges for portable air conditioners

A

6000 - 18 000 Btuh