Step 4 of 5•5 minutes read
Portable Gas Sampling and Monitoring
SOLAS Chapter XI-1/7 makes it mandatory for all vessels to carry portable gas detectors. As a minimum, the portable gas detectors will need to be capable of testing for concentrations of oxygen, flammable gas, carbon monoxide, and hydrogen sulphide prior to entering enclosed spaces.
The proper procedure for testing the atmosphere and how to properly use the equipment provided is paramount and must be known by all personnel working with such instruments. Multi-gas instruments capable of measuring the following are most commonly found on board ships:
- Flammable Gases.
- Carbon Monoxide.
- Oxygen.
- Hydrogen Sulphide.
The crew must be aware that these instruments should be tested and calibrated at regular intervals as per the manufacturer’s instructions.
Personal Gas Monitors
Multi-gas instruments are also supplied in compact units fitted with an alarm function. These units are used as personal protective equipment (PPE) during tank entry, entry into an enclosed space or even on deck where the presence of gases might exist. These instruments continuously monitor the content of the atmosphere and provide an audible and visual alarm when unsafe concentrations of specific gases are detected. This ensures an adequate warning to the user of unsafe conditions.
Personal Gas Detector. Photo: Jörgen Språng
Testing the Atmosphere
Testing of the atmosphere as per the company’s safety management system (SMS) needs to be carried out when an enclosed space entry including an entry in a tank that carried cargoes containing H2S, and additional at frequent intervals on deck when the loading of cargoes containing hydrogen sulphide is underway. Prior to entry, a thorough test of the atmosphere inside the tank must be performed.
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The first test will be carried out by the competent officer as part of the pre-entry testing required by the permit to work.
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The atmosphere will then be monitored by the personal gas detectors provided to the crew members inside the enclosed space.
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Additional checks for the atmosphere inside the tank will be carried out as required, usually at frequent intervals.
No one should enter an enclosed space until the atmosphere in the space has been tested appropriately and found to be safe, and such testing is carried out with approved and calibrated instruments.
It is of paramount importance to ensure that testing of the atmosphere is carried out in various locations and at different levels inside the enclosed space in order to ensure that the space is truly safe for entry. This is done due to the different weights of the gases.
Note: In the case where the atmosphere is found unsafe, and the work is required to be done, proper personal protective equipment (PPE), including self-contained breathing apparatus, must be worn prior to entry.