GAS DETECTORS IN SHIPS

GAS DETECTORS IN SHIPS

A gas detector is important marine equipment used to detect leakage of hazardous gases on the ship and on offshore industries. Over time, gas detectors have changed and are helping mariners in avoiding possible mishaps.

Gas detectors are been used in many industries from the time people were aware of the harmful effect of gases in closed space and hazardous environments. In early periods of mining, much before sensors came to place, canaries(a bird) were used to detect gas leakages. In mines, canaries were taken down in cages and if they stopped singing, the miners would know the deficiency of gas. We’ve come a long way since the 19th and early 20th centuries. Now gas detection methods are much more precise – and much less harmful to animals.

Gas detectors use a sensor to measure the amount of gas in the air. The sensors are calibrated in such a way to measure and produce an electric current when a chemical reaction caused by a specific gas occurs. The sensor will monitor the current and alarm the user when the presence of gas approaches hazardous level. The earlier gas detector could only sense one gas at a time but now multiple gases can be measured – most commonly, oxygen (O2), flammable gases or vapours (LEL), hydrogen sulphide (H2S) and carbon monoxide (CO). These are the gases that a 4-gas detector monitors, the minimum requirements set out by SOLAS Regulation XI/1-7.

Gas detector configuration is based on the tank and vessel type. The three main considerations are usually:

1. Monitor for sufficient oxygen

2. Monitor for explosive gasses

3. Monitor for toxic gases based on the hygienic limits.

Oxygen and explosive gases are easily determined as necessary to monitor, but deciding which toxic gases to monitor depends on the tank and vessel type.

Most portable detectors use a pellistor/catalytic bead LEL sensor. These gas detectors function only when the air surrounding has at least 10% of oxygen so that it avoids the build-up of tar and unburned fuel. Theoretically, the sensor can last up to four years but it is very sensitive and can easily break if the monitor is knocked or dropped.

Most gas detectors have only a lifespan of 3 years and over that, they need to be replaced or serviced. This can be a costly process that will leave the detector out of action, so you also need extra instruments to make sure you’re covered while the repair work is being carried out. Other components like backlight screens and audio alerts will begin to develop faults too so it’s important to keep detectors well-maintained. KELISAIKE provide excellent service engineers to fix any issues with gas detectors while your ship is in the bay. 

Pellistor sensors

Pellistor sensors can be damaged after frequent detection of hazardous gases. They might get poisoned over the long run. Contaminated sensors may not be detected by gas levels and slowly become less responsive. Their performance depends on testing using calibration and bump-testing to make sure they detect the right amount of gas to help mariners to act under any emergency and to keep the ship safe.

Infrared sensors

Infrared sensors don’t need oxygen, they work in a completely inert gas atmosphere. This makes them ideal in confined spaces where oxygen availability is an issue. Infrared sensors don’t get damaged by hazardous gases accumulating around them over time. They’re also immune to sensor poisoning so there’s no need for calibration to ensure the gas detector is functioning correctly. A traditional pellistor sensor uses a heated aluminium coil. The coil takes too much power and drains the whole system. Gas detectors using infrared sensors are energy efficient. They are run on batteries that don’t drain too quickly.

You can contact the best marine equipment servicemen from KELISAIKE to service, repair and replace your ships gas detector.

sally@njklsk.cn