Objectives

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Objectives

• Summarize Electric Power Measurement
• Learn about CO and CO2 measurement and
  instrumentation
• Discuss next week field measurements

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Portable (Field) power meter and data logger
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Single phase two wire
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Single phase three wire
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Three phase four wire
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Electric power meters
Large variety

power meter with data logger
Inexpensive power meter
Power meter with power supply
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Overview of CO2 and CO

• Why make these measurements in the field?
• Some background information
• Types of devices for each (overview)
• Pros and cons of devices (including accuracy)

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CO2 - Standards Guidelines

• OSHA 5,000 ppm (8-hr average)
• ASHRAE (62-1999) Cindoor Coutdoor lt 700 ppm
• U.S. Navy (subs) 6,000 10,000 ppm
• Observations in medical literature (Clark, 1996)
• 1,200 ppm _at_ 15 min (fatigue, lack of
  concentration, short. breath)
• 1,200 ppm long-term (calcium deposition in
  tissues)
• gt 2,500 ppm symptoms of oxygen deprivation in
  children
• gt 60,000 ppm (6) possible narcosis / death
  (within minutes)

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Carbon Dioxide (CO2)

• Metabolic generation rate
• Ventilation requirements
• ASHRAE Standard 62.1

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Metabolic Generation Rate

• ASTM D6245
• Also ASHRAE Fundamentals Ch. 8 (2005)

AD 1.8 for adult, 0.8 - 1.4 for kids
RQ 0.83 when M 1 met RQ 1 when M 5 met
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ASHRAE Standard 62.1-2007
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CO2 Measurement Techniques

• Non-dispersive infrared (NDIR) most common
• Electrochemical (reduce CO2 / generate current)
• Photoacoustic (CO2 absorbs / T up to P pulse)
• Potentiometric (CO2 to solution changes pH)
• Gas chromatography w/ MS or TCD
• High sensitivity
• High cost

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Non-dispersive infrared (NDIR)

• Measures the infrared light absorbed by carbon
  dioxide as it passes through a flow-through IR
  absorption cell
• Possible interference from other ionic species
• - Interferences from other IR-absorbing gases
  are minimized by use of a highly
  wavelength-specific detector
• Issues
• ..

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CO2 NDIR Detection

• See ASHRAE PDS IV
• Absorption of IR light (CO2 peak absorb _at_ 4.3 µm)
• IR light source passed through narrow band filter
• Higher CO2 greater IR absorption
• Interferences H2O, CO, CH4 (absorp 4 7 µm)
• Accuracy 50 to 100 ppm up to 10,000 ppm
• Hold calibration a long time ???
• Cost expensive for HVAC industry , affordable
  for Field work

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Electrochemical

• CO2 diffuses into the sensor through a porous
  membrane to the working electrode where it is
  case electrochemical reaction. This reaction
  results in an electric current that passes
  through the external circuit. the counter
  electrode is a reduction.
• Advantages/disadvantages
• Can be very inexpensive
• Drifting,.

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Carbon Monoxide (CO)

• Major sources
• Cigarette smoke
• Incomplete bringing in HVAC and Cooking systems
• Car exhaust
• .
• Standards
• 9 ppm (8-hour average) - NAAQS
• 35 ppm (1-hour average) NAAQS
• 50 ppm STEL/TWA OSHA
• 400 ppm (15 minutes) - ACGIH
• 1,500 ppm (30 min) IDLH (OSHA)

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Example Cooking Natural Gas
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Measurement of Carbon Monoxide

• Electrochemical (common for hand held or home)
• Two electrodes
• Oxidize CO to CO2 current generated
• Biomimetic (gel cell)
• Synthetic hemoglobin darkens in presence of CO
• Semiconductor (wires of tin dioxide / ceramic
  base)
• CO reduces resistance
• High CO
• Non-Dispersive Infrared Detection (NDIR)
• Used for emissions testing
• Absorption band

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Instruments for CO andCO2 that you will use

• HOBO U12 (datalogger)
• Telaire 7001 CO2 analyzer (NDIR)
• HOBO CO Analyzer (electrochemical)
• Specs
• http//onsetcomp.com/products/sensors/tel-7001
• http//onsetcomp.com/products/data-loggers/h11-001
  

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Lab exercises - next week

• PRC on Tuesday
• preparation
• Field
• Wednesday or Thursday

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