Gas detectors for vessels is a device that detects the presence of gases in ships, often as part of a safety system. SOLAS regulations XI- 1/7 requires that vessels have at least one portable gas monitor on board for oxygen and flammable gas detection. This type of equipment is used to detect a gas leak and interface with a control system so a process can be automatically shut down.
Why is gas detection required?
Gas detection equipment measures a gas concentration against a calibration gas which acts as a reference point. Some gas detection monitors only can detect a single gas, some gas detectors can detect several toxic or combustible gases and even combinations within one device.
Marine applications often generate high humidity and dirty conditions. Detection is required from O2 monitoring in cargo room exhausts, to monitoring flammable and toxic gases within various void spaces, to pump room or cabins, fixed systems with sampling are all commonly used in marine settings.
Gas detection is required within the marine industry due to the high temperature surfaces housed in an engine room, as well as the short circuit in the electrical system. Both factors combine with smoking or other domestic sources of fire or a reaction in the cargo, leave ships extremely vulnerable to fires. Gas detection is therefore a vital piece of equipment in protecting the lives of those who work on these vessels. This is key as many seafarers lose their lives every year due to the toxic working environment, they work in. Therefore, detecting such hazards before they become fatal, is essential to contain the damage which can take the form a disaster, meaning gas detection is one of the most important pieces of equipment on a marine vessel.
What are the gas hazards?
There are several different gas hazards, dependant on the vessel type, such as FPSO (floating, production, storage, and offloading), tankers, ferries, submarines, general or cargo tanks.
FPSO and tankers house flammable gases and hydrogen sulphide. Therefore, there is a gas hazard risk of flammable gas leaks within the pump rooms. Gas hazards in confined spaces are another hazard, as there may be inerted tanks or voids, which therefore may be too much or too little oxygen in these confined space environments and where inerting gases are stored. There are also hydrocarbon oxygen risks during the purging of tanks (from %Volume to %LEL (Lower Explosive Limit)).
- Carbon monoxide (CO) and nitrous oxide (NOx) are housed on ferries as a result of the accumulation from vehicle exhausts, as both are poisonous gases, they are both gas hazards to be aware of.
- Submarines house hydrogen within battery rooms. Along with CO2 leaks from air conditioning systems.
- On general vessels, CO and NOx are present engine rooms. Along with hydrogen sulphide (H2S) and O2 being depleted in bilges, that arise from the on-board sewage treatment plant. Vessels that carry food produce, such as grain, will sometimes be at risk of H2S.
- Cargo Tanks house vapour emission control systems which are used to analyse waste vapour gas for oxygen gas content. The system includes a pressure transmitter to monitor the pressure on the waste vapour line.
Products installed on any marine vessel must comply with internationally recognized regulations. Therefore, the international standard that applies to a vessel depend upon where it is registered. It is essential that products sold for use on a vessel comply with the standards relevant to the country in which the ship is registered. For example, products fitted to a European-registered vessel undergoing a re-fit in Singapore must comply with the European MED (Marine Equipment Directive) directive.
There are several different standards that comply to different regions:
- EU (European Union) countries: MED (Marine Equipment Directive 96/98/EC).
- North America: US Coast Guard (USCG) regulations.
- Other countries: SOLAS (Safety of Life at Sea) regulations provide the minimum requirements, however individual countries will require compliance with the standards of their chosen marine insurance body (e.g., BV, DNV etc).
Why use detectors?
Gas detectors measure and specify the concentration of specific gases within the air via different technologies.
Gas meters are also used on-board ships to measure the hydrocarbon content, explosion hazard risk, and the oxygen analysers. Under the current guidelines cargo tanks or any enclosed space on-board the ship must be tested to ensure that the space is gas-free along with ample amount of oxygen for any required personnel to work there. These circumstances include; prior to starting any repair work or before loading as quality control.