OXYGEN
O2
MW: 32.00
CAS: 7782-44-7
METHOD: 6601, Issue 2
6601
RTECS: EL9450000
EVALUATION: FULL
OSHA : 19.5% (v/v) minimum NIOSH: 19.5 to 25% (v/v) @ 760 mm Hg ACGIH: no standard
Issue 1: 15 May 1985 Issue 2: 15 August 1994
PROPERTIES: gas; d 1.331 g/L @ 20 °C; partial pressure 21.23 kPa (159.22 mm Hg, 20.9% v/v) @ sea level
SYNONYMS: None.
SAMPLING SAMPLER:
PORTABLE MONITOR
DIRECT-READING
MEASUREMENT OXYGEN
TECHNIQUE:
ELECTROCHEMICAL SENSOR
ANALYTE:
oxygen
FLOW RATE: samples by diffusion; no pump needed RESPONSE TIME:
VOL-MIN: -MAX:
1L none
SHIPMENT:
routine shipment of instrumentation
CALIBRATION:
fresh air or compressed calibration standards
SAMPLE STABILITY:
bag samples stable 4 h
RANGE:
0 to 25% (v/v) O 2 in N 2 (linear response)
fresh air or compressed synthetic air from cylinders
SENSITIVITY:
BLANKS:
PRECISION (Sr):
5 to 25 sec for step change from 21% (v/v) O 2 to 19.5% (v/v) O 2 [1] gas
tank
0.1% (v/v) O 2 0.096 [1]
ACCURACY RANGE STUDIED:
15 to 21% (v/v) O 2 in air [1]
BIAS:
none [1]
ˆ ): 0.096 [1] OVERALL PRECISION (S rT ACCURACY:
± 19%
APPLICABILITY: The working range is 0 to 25% (v/v) O 2. For some monitors, the working range is 0 to 100%. This method may be used in work atmospheres to determine available O 2 levels and is particularly useful for determining safe entry conditions into confined work spaces. Many units are small enough to be worn on the person and may be used to obtain personal breat hing zone samples.
INTERFERENCES: Levels of up to five times the TLV of many common industrial chemicals did not adversely affect the studied sensors [1]. Pressure and temperature changes do affect the sensors. Most units are equipped with temperature-compensati ng circuitry, but some take up to 1 h to equilibrate. Several models include pressure-compensating circuitry.
OTHER METHODS: None studied by NIOSH. This method was written as a result of evaluation of 18 commercially available oxygen monitors [2].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
