Application Note

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Application Note

Fundamental IAQ/HVAC

measurements with the

Fluke 975 AirMeter

™

F r o m t h e F l u k e D i g i t a l L i b r a r y @ w w w . f l u k e . c o m / l i b r a r y

The 975 gathers ten fundamental

IAQ parameters: Temperature, Humid-

ity, Dew Point Temperature, Wet Bulb

Temperature, Carbon Dioxide, Carbon

Monoxide, Air Velocity, Air Volume,

and Percentage of Outdoor Air (calcu-

lated from temperature or CO

). This

application note reviews those param-

eters and the associated functions on

the 975. For more detailed informa-

tion, see other app notes from the

Fluke HVAC/IAQ library.

Temperature and Humidity

Fundamentals

Temperature and humidity are

the foundation of IAQ. We rely

on HVAC equipment to maintain

acceptable temperature, humidity

and ventilation levels for occupant

health and comfort, and, now more

than ever, to help regulate building

health.

The relationship between HVAC

equipment, occupied space require-

ments, building materials, weather

conditions and pressure differen-

tials is an ever-changing dynamic

process. We expect the HVAC

equipment to maintain 68° F to 70°

F at 30% relative humidity in the

winter and 74° F to 76° F at 40%

to 60% relative humidity in the

summer.

How easily this is achieved

depends on many factors includ-

ing geographical location, HVAC

equipment selection and operating

criteria and building design. Tem-

perature control and ventilation

are the primary concern in dry cli-

mates, while humid climates battle

humidity related issues.

In every climate, indoor conditions

must be maintained to inhibit or

prevent the proliferation or colo-

nization of dust mites, bacteria,

viruses, fungus and mold spores,

and other bioaerosols. Forty to

forty-five percent relative humidity

is becoming the recognized ideal

indoor condition for human com-

fort, structural and materials integ-

rity, and discouraging microbial

proliferation.

How the 975 measures it

After the Fluke 975 AirMeter

™

test tool completes its startup

test, the main screen simultane-

ously displays dry bulb tempera-

ture (°F or °C), relative humidity

(%RH), CO ppm (parts per mil-

lion), and CO

ppm. Soft keys*

toggle between relative humidity

(%RH), wet bulb temperature

(WBT), or dew point temperature

(DPT). When the “MIN MAX” but-

ton is pressed, the meter will

record the minimum, maximum,

and average of all available

readings.

*“Soft keys” are meter buttons whose

functions vary with each change in

meter screen display

Measuring air velocity in a duct.

Summary of content (4 pages)

PAGE 1
Fundamental IAQ/HVAC measurements with the Fluke 975 AirMeter™ The 975 gathers ten fundamental IAQ parameters: Temperature, Humidity, Dew Point Temperature, Wet Bulb Temperature, Carbon Dioxide, Carbon Monoxide, Air Velocity, Air Volume, and Percentage of Outdoor Air (calculated from temperature or CO2). This application note reviews those parameters and the associated functions on the 975. For more detailed information, see other app notes from the Fluke HVAC/IAQ library.
PAGE 2
Carbon Monoxide Fundamentals Carbon Monoxide (CO) is a product of the incomplete oxidation of carbon during combustion and is undesirable at any levels in an occupied space. Carbon monoxide is colorless, tasteless and odorless. The longer the exposure and the higher the concentration, the more CO is retained by the blood, leaving less and less room for oxygen. At lower levels of exposure, CO causes flu-like symptoms such as headaches, dizziness, disorientation, nausea and fatigue.
PAGE 3
How the 975 measures it The Fluke 975 measures CO2 automatically and also uses it to calculate the percentage of outside air. Select “% OUTSIDE AIR” and you’ll be prompted for “CO2” or “Temp” calculations. Next enter the return air value, the mixed air value, and then the outside air value. The greater the differential between indoor and outdoor temperature or CO2 values, the greater the accuracy achieved.
PAGE 4
When the velocity function is selected, the screen display prompts the user to press a soft key for either “Volume Flow Rate” or “Air Velocity”. If “Air Velocity” is selected, the AirMeter screen displays a dynamic live velocity reading at standard conditions (69.98° F and 29.93 in Hg). A soft key enables the user to toggle between “Standard” readings and “Actual” readings, which are compensated for pressure and temperature.