confined space air quality testing equipment

A confined space air quality testing equipment holds a very important role in ensuring a safe entry.

As you may already knew that oxygen deficiency, flammable gases, and vapors, and toxic gases are present in a confined space (You can read the previous article about hazards in confined space for more hazards information).

Besides that, such testing equipment is also used for air monitoring during confined space work in progress.

Because of its importance, confined space air quality testing equipment becomes one of the mandatory equipment in the confined space entry equipment list.

Before showing you the top 3 air quality testing equipment, let’s see some common questions related to confined space gas testing.

What Gases Are Tested in Confined Space?

According to OSHA’s confined space standard 1910.146, the internal atmospheric must be tested before a worker enters a confined space.

The atmospheric testing includes oxygen, toxic gases, and flammable gases, vapors, or mist.

And the testing must use a calibrated direct-reading instrument.

confined space instrument

What is The Correct Order of Atmospheric Testing?

The above OSHA’s standard states that the correct order of atmospheric testing are oxygen, flammable gas, vapor or mist, and toxic gas and vapor.

The limit of oxygen, flammability, and toxicity that required confined space permit are shown by the following table.

ParameterPermit-Required Confined Space
Oxygen<19.5% or >23.5%
Flammability>10% lower flammable limit (LFL)
Toxicity>50% permissible exposure limit (PEL) or threshold limit value (TLV)

What Must be Continually Monitored During Work in A Confined Space?

We shall monitor all the above parameters – oxygen, flammability, and toxicity – during a confined space work in progress.

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This is to monitor any change that may happen inside it.

If the testing instrument alerts a change, immediately all workers shall move out from the confined space.

Remember that a change may happen due to any reason. Suppose unintended operation of block valve, exhaust blower trouble, pipe leakage, etc.

Best 3 Air Quality Testing Equipment

Okay, now it is time for me to show you the best 3 air quality testing equipment that I took from

Besides user reviews, I also chose the product based on its features.

Here are the review results:

ParameterHZXVOGEN Portable Gas DetectorMULTIGAS DetectorBW Technologies MCXL-XWHM-Y-NA GasAlertMicroClip
Analyzed gasesO2 (0-30%)
Ex (0-100% LEL)
H2S (0-100ppm)
CO (0-1000ppm)
O2 (%)
Ex (%)
H2S (ppm)
CO (ppm)
O2 (%)
Ex (%)
H2S (ppm)
CO (ppm)
Response time< 30 seconds< 30 secondsn.a
Battery4.2V rechargeable lithium, 1800mAhrechargeable lithium, 1500mAhrechargeable lithium
Battery life10 hours12 hours12 hours
Data loggingn.a500 alarm recordsn.a
AlarmIntelligent voice broadcast: sound, light, vibrationLED alarm, buzzer, vibrationLED, alarm
LCD displayYesYes, colored with graphYes
USB chargerYesYesYes
Weight, lb2.010.730.42
Dimension13.5×7.0x2.5 cm14.5×6.9×2.8 cm11.3×6.0x3.1 cm
High temp protectionYesNon.a
Easy to carryYesYesn.a
Connect to other gas detectorsn.aYesn.a
Customer rating (as of July 19, 2020)4.4 of 5.0,
18 reviews
4.8 of 5.0,
18 reviews
4.4 of 5.0,
28 reviews
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