Draeger tubes and confined space entry: what the OSHA standard asks for and where a tube fits
OSHA’s permit-required confined space standard requires the atmosphere to be tested before entry with a calibrated direct-reading instrument, in the order oxygen, then flammable gases and vapors, then toxic air contaminants, and to be monitored as necessary while anyone is inside (29 CFR 1910.146(c)(5)(ii)(C) and (d)(5)). A Draeger tube gives one momentary reading for one gas and does not alarm, so it is not the continuous monitor the standard has in mind; the handbook itself says the explosion hazard is detected first, preferably with oxygen and carbon monoxide, with a multi-gas instrument such as the Dräger X-am, before tubes are used (p. 57). Where tubes fit is the toxic contaminant the monitor has no sensor for: the handbook describes sampling a sewer, shaft or tank from outside through an extension hose of 1 to 15 m (30 m on the X-act 5000) with the tube at the far end (section 2.7, p. 48).
Draeger accuro detector tube hand pumpBellows pump, 100 mL (± 5 %) per stroke, 1 to 50 strokes and higher, no power supply (handbook p. 31)Why not test a manhole with a tube alone? The standard names the instrument (calibrated, direct-reading) and the order (oxygen, flammables, toxics), and requires monitoring during entry. A tube reads one gas, once, after a set of strokes, with no alarm; a four-gas monitor reads oxygen, LEL, H2S and CO continuously and alarms. The handbook’s own measurement strategy for unknown atmospheres (section 2.9) puts the combustible, oxygen and CO measurement first, with a multi-gas warning device, because combustible substances were present in 60 to 65 % of the incidents Draeger evaluated; tubes then identify and quantify the specific toxic gases (p. 57). The two instruments answer different questions.
What 1910.146 requires and where each instrument fits
Where a Draeger tube is the right tool around a confined space
Within the limits above, the handbook describes the tube as a quick decision-making tool (p. 57):
- A toxic gas with no sensor on the monitor: the handbook lists tubes for several hundred substances; the gas pages here cover 98.
- A specific identification after a simultaneous test set or a monitor alarm: the handbook states that when a critical concentration is found, the actual concentration of that gas is then measured with the corresponding Dräger tube (p. 55).
- A drum, vent, pipe or tank sample before deciding what to bring in: one tube, one pump, a reading in seconds to minutes.
- Breathing-air checks on supplied-air systems: the Aerotest tubes (CO, CO2, water vapor, oil) are a separate, handbook-described application (section 2.8).
Questions people ask
Can a Draeger tube be used for confined space entry testing?
It can measure a specific toxic gas from outside through an extension hose, but OSHA requires a calibrated direct-reading instrument, the oxygen-flammable-toxic order and monitoring during entry; a tube gives one reading and does not alarm (1910.146(c)(5)(ii)(C), (d)(5)).
What order does OSHA require for testing?
Oxygen, then combustible gases and vapors, then toxic gases and vapors (1910.146 Appendix B; (d)(5)(iii)).
How do I sample a tank or sewer with a tube from outside?
With a Draeger extension hose: adapter end on the pump, the tube in the holder at the free end lowered into the space; 1 to 15 m, 30 m with the X-act 5000 (handbook p. 48).
What does the Draeger handbook say about unknown atmospheres?
Detect the explosion hazard first, preferably with oxygen and CO, using a multi-gas instrument, before using tubes; combustibles were present in 60 to 65 % of the incidents evaluated (p. 57).
Which tubes are for breathing air?
The Aerotest -P tubes for CO, CO2, water vapor and oil, used in the Aerotest units (handbook section 2.8); see the Grade D breathing air guide.
Related guides
Gas detection for confined space entryWhat to test and the orderDetector tubes vs electronic monitorsWhen each is usedWhich Draeger tube range covers the OSHA PEL or the IDLH? Reading the limits next to the rangesRange and exposure limitsThe Draeger accuro pump: how it works, the leak check, strokes and the kitsaccuro pumpStandards and ratings on this page are as published in the documents named and by the manufacturers named. The employer’s hazard assessment and written program decide what applies at a given workplace. Verify a rating on the product and its spec sheet before use.