Page:NIOSH Manual of Analytical Methods - 6601.pdf/1

 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