Confined Space Entry Gas Detectors Selection Guide

Portable confined space entry gas detectors are most commonly used in industrial sectors. They're required to carry out pre-entry tests into confined spaces and to continue monitoring for hazardous gases during works. Ultimately, these gas detectors are designed to keep people safe at work.

We've composed a guide which discusses the most important factors that you need to consider when buying a confined space entry gas detector.

1. Gas Sensors

Your choice of gas detector required for your confined space testing rests on the choice of sensor. Some instruments can only accommodate a certain technology type of sensor. For example, you may need to add an infrared sensor for the detection of carbon dioxide. Therefore, sensor selection should reflect the known and potential atmospheric hazards within the application.

Most confined space gas detectors employ an oxygen sensor, a catalytic sensor for flammable/combustible gases and one or two electrochemical sensors for detecting specific toxic gases.

NOTE: if you are unsure of what gas hazards are potentially present, refer to an MSDS. Alternatively, a1-cbiss can help conduct a hazard assessment before you purchase those new instruments.

2. Alarms

Once target gas limit values are reached or exceeded, the alarm will alert the user. Alarms can be in the form of visual, audible or vibration.

Alarms should be in excess of 90dB and highly visible to attract the attention of the worker.

Some gas detectors are designed with intuitional alarms that tell the worker exactly what to do in the event of an alarm.

Wireless communications enable access to real-time instrument readings and alarm status (including Man-Down alarm) from any location. As a result, this can help facilitate faster, data-driven decision-making to save lives and protect assets.

3. Sampling Method

In confined space testing there are two primary means of exposing the sensor to the gases present;

•  A sample draw uses a pump to draw a sample back into the instrument for analysis. Drawing a sample protects the user by eliminating any need to enter the space or by providing pre-entry checks if the space has to be entered.

•  a1-cbiss recommend buying an “attachable” pump for a confined space detector. This permits users to remove the pump and operate the instrument in diffusion mode when a sample pump is not required. As a result, this technique is not only more cost-effective but it can enhance battery lifetime too.

•  Most recommended gas detector sensors operate by diffusion. They rely on the inherent movement of the air to direct a sample to them.
Diffusion detectors can stand up to the challenge of toxic gases. If you need to be free of moving parts and pumps, diffused pumps are the perfect fast response solution for confined spaces.

4. Approvals

Your detector is designed to detect explosive gases, therefore it is essential that it is ATEX approved.

You must ensure your detector displays the ATEX logo which proves it's been designed to be intrinsically safe.

Intrinsically safe detectors are required to keep electrical energy at a minimum. In doing so, the detector can guarantee that there won’t be enough power to cause a spark.

Consideration must be given to the application where the gas detector is to be used. For example, in the marine industry, a confined space detector must be used in accordance with the amendments to SOLAS regulation XI-1/7 contained in IMO Resolution MSC.380 (94):

5. Data logging

There are two types of data storage: datalogging and event logging. Event logging will only show alarm events. Gas detectors that have event logging will only have capability for a certain number of events.

Datalogging allows data to be recorded at given intervals over a period of time.

The capability to provide documentation of proper use can significantly reduce liability exposure, and in the long run save much more than the cost of including datalogging in the instrument at the time of purchase.

Aside from keeping records, using your gas detector for datalogging will allow you to recognise any potential dangerous trends. Based on long-term exposure and detector usage, data-driven decisions can be made.

6. How It's Worn

In normal operation, most confined space instruments are worn on the belt or a helmet. They are used with a shoulder strap or chest harness, or held by hand.

Tip: All gas detectors should be positioned within 30cm of the wearer’s mouth for effective personal safety.

7. Accessories

Be sure to verify which accessories are included in the purchase price for the instrument.

If the gas detection instrument includes a rechargeable battery, does the price include a battery charger? Do the accessories include a sample draw kit or automatic pump. Concussion proof boot? Clips or straps? Calibration cup?

Be sure to factor in the extra cost of accessories when considering your purchase!

In summary, these gas detectors are designed to keep people safe at work. Follow the points in this guide and you're on your way to finding the most suitable confined space gas detector.

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