Page:NIOSH Manual of Analytical Methods - 6604.pdf/1

 CARBON MONOXIDE

CO MW: 28.00 RTECS: FG3500000 METHOD: 6604, Issue 1

6604

CAS: 630-08-0

EVALUATION: FULL

OSHA : 50 ppm NIOSH: 35 ppm; C 200 ppm ACGIH: 25 ppm (1 ppm = 1.14 mg/m3)

PROPERTIES:

Issue 1: 15 May 1996

gas; BP -192 C; MP -207 C; vapor density (air=1) 0.967; flammable (explosive) limits in air 12.5 to 74.2%

SYNONYMS: monoxide; carbon oxide; carbonic oxide; flue gas

SAMPLING SAMPLER:

PORTABLE DIRECT-READING CO MONITOR

VOL-MIN: -MAX:

instrument dependent none

SHIPMENT:

routine shipment of instrumentation

SAMPLE STABILITY:

MEASUREMENT TECHNIQUE:

ELECTROCHEMICAL SENSOR

ANALYTE:

carbon monoxide (CO)

CALIBRATION: - ZERO: -SPAN:

at least 7 days @ 25 C [1] (aluminized air bags) RANGE:

BLANKS:

fresh air or compressed CO-free air from cylinder ACCURACY

RANGE STUDIED:

0 to 200 ppm

BIAS:

- 1.7% [2]

OVERALL PRECISION ( ACCURACY:

CO-free air standard cylinders of span gas in the desired range

rT

):

0 to 200 ppm

ESTIMATED LOD:1 ppm PRECISION ( r):

0.035 @ 20 ppm 0.012 @ 50 ppm 0.008 @ 100 ppm [2]

0.022 [2] ± 6.0%

APPLICABILITY: Portable, direct-reading carbon monoxide monitors are applicable to any work environment for personal or area monitoring.

INTERFERENCES: Several gaseous pollutants (e.g., NO2, SO2 ) may cause an interference at levels over 5 ppm. If these or other pollutants are known or suspected to be present, use a monitor with a chemical interference scrubber over the sensor. Unknown pollutants may require further experimentation to determine their effect on the sensor. As tested, SO2 (5 ppm), CO2 (5000 ppm), methylene chloride (500 ppm), diesel fuel (6 µL/L, about 0.3 ppm benzene), and gasoline vapor (1 µL/L, about 1 ppm benzene) had no impact on most monitor readings [2]. Some monitors are equipped with a chemical interference scrubber while others offer this as an option.

OTHER METHODS: Bag samples may be collected in aluminized bags (2-L or larger) and analyzed later by placing the calibration cap over the sensor and pumping the sample across the sensor at a nominal rate of 0.250 L/min with a personal sampling pump.

NIOSH Manual of Analytical Methods(NMAM), Fourth Edition, 5/15/96