UL 920401:2017

$78.65

Performance Requirements for Instruments Used to Detect Oxygen-Deficient/Oxygen-Enriched Atmospheres

Published By	Publication Date	Number of Pages
UL	2017-11-03	43

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Category: UL

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Description

1 Scope

1.1 This Standard addresses the details of construction, performance, and testing of portable, mobile,and stationary electrical instruments used to provide a warning of the presence of oxygen-deficient oroxygen-enriched atmospheres.

NOTE — Human physiology responds to oxygen pressure, not oxygen concentration; however,they are physiologically equivalent at one normal atmosphere. (See Clause 3, Normalatmosphere.) The normal atmosphere is composed approximately of 20.9 percent oxygen (21.2kPa)(3.07 psia), 78.1 percent nitrogen (79.1 kPa)(11.5 psia), and 1 percent argon (1.01 kPa)(.146psia) by volume with small amounts of other gases. Reference: National Institute for OccupationalSafety and Health, (NIOSH), Pub. No. 80-106.

1.2 This Standard applies to mains-connected instruments rated at 250 V nominal or less, and toportable, mobile, and stationary battery-powered instruments.

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

1.4 This Standard applies to instruments providing at least one range that includes 15 to 20.9 (15.2 to21.2 kPa)(2.20 to 3.07 psia) or 20.9 to 25.0 (21.2 to 25.3 kPa)(3.07 to 3.63 psia) volume percent oxygenat one normal atmosphere. Hereafter, the volume percentage of oxygen at one normal atmosphere will beexpressed as "percent oxygen."

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

1.6 For instruments with multiple ranges, this Standard does not apply to any range that does not includenormal atmospheric oxygen pressure (20.9 percent oxygen or 21.2 kPa[3.07 psia] at one normalatmosphere).

1.7 This Standard does not apply to oxygen-monitoring instruments of the laboratory or scientific type,which are used for analysis or measurement in process control and process-monitoring applications orinstruments with full-scale oxygen concentrations less than 15 percent (15.2 kPa)(2.20 psia) or greaterthan 30 percent (30.4 kPa)(4.41 psia) oxygen.

NOTE — The user should specify instrumentation that will provide a higher level of accuracy thanthe minimum tolerances of this Standard if required by the application risk.

1.8 The user should be aware of the effects of altitude and barometric pressure on both the instrumentand the user. The effects are not intended to be evaluated by this performance Standard.

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