ISA 92.04.01 PART I

This Standard addresses the details of construction,performance, and testing of portable, mobile, and stationaryelectrical instruments used to provide a warning of the presence ofoxygen-deficient or oxygen-enriched atmospheres.

NOTE — Human physiology responds to oxygenpressure, not oxygen concentration; however, they arephysiologically equivalent at one normal atmosphere. (See Clause 3,Normal atmosphere.) The normal atmosphere is composed approximatelyof 20.9 percent oxygen (21.2 kPa)(3.07 psia), 78.1 percent nitrogen(79.1 kPa)(11.5 psia), and 1 percent argon (1.01 kPa)(.146 psia) byvolume with small amounts of other gases. Reference: NationalInstitute for Occupational Safety and Health, (NIOSH), Pub. No.80-106.

This Standard applies to mains-connected instruments rated at250 V nominal or less, and to portable, mobile, and stationarybattery-powered instruments.

This Standard applies to instruments suitable for use in anambient temperature range of at least -10°C to 50°C (+14°F to+122°F ).

This Standard applies to instruments providing at least onerange that includes 15 to 20.9 (15.2 to 21.2 kPa)(2.20 to 3.07psia) or 20.9 to 25.0 (21.2 to 25.3 kPa)(3.07 to 3.63 psia) volumepercent oxygen at one normal atmosphere. Hereafter, the volumepercentage of oxygen at one normal atmosphere will be expressed as”percent oxygen.”

This Standard applies to instruments that provide at least oneoxygen-deficient alarm that cannot be adjusted below 18 percent(18.2 kPa)(2.64 psia) oxygen or at least one oxygenenrichment alarmthat cannot be adjusted above 25 percent (25.3 kPa)(3.67 psia)oxygen.

For instruments with multiple ranges, this Standard does notapply to any range that does not include normal atmospheric oxygenpressure (20.9 percent oxygen or 21.2 kPa[3.07 psia] at one normalatmosphere).

This Standard does not apply to oxygen-monitoring instruments ofthe laboratory or scientific type, which are used for analysis ormeasurement in process control and process-monitoring applicationsor instruments with full-scale oxygen concentrations less than 15percent (15.2 kPa)(2.20 psia) or greater than 30 percent (30.4kPa)(4.41 psia) oxygen.

NOTE — The user should specify instrumentationthat will provide a higher level of accuracy than the minimumtolerances of this Standard if required by the applicationrisk.

The user should be aware of the effects of altitude andbarometric pressure on both the instrument and the user. Theeffects are not intended to be evaluated by this performanceStandard.

Purpose

This Standard provides minimum performance requirements ofelectrical instruments for the determination of oxygen(O₂) content in air in order to enhance the safety ofpersonnel.

ISA-RP92.04.02, Part II, the companion recommended practice tothis Standard, establishes user criteria for the installation,operation, and maintenance of oxygen-monitoringinstrumentation.

Edition:

07

Published:

01/01/2007

ANSI:

ANSI Approved

Number of Pages:

38