Wind turbines (or wind towers as they’re sometimes called) harvest wind energy to generate electricity. Due to the number of moving parts, engineers must perform maintenance work which includes repair, inspection and maintenance of equipment within the several potentially hazardous compartments of the towers.
The hazardous compartments that engineers perform maintenance in can be classified as confined spaces; the basement electrical room, telecom vault, the hub, nose cone, and turbine.
When working in confined spaces, Oxygen depletion is always a concern. Toxic fumes can arise from heat or electrical sparks igniting solvent-based resins or other volatile organic compounds (VOCs) used to lubricate turbines, blades, and electrical apparatus. Engineers who need to crawl into the narrow channel to inspect and repair the blades or fibreglass skin can be subjected to off-gassing from battery acids or VOCs. The decomposition of dead animals (birds or rodents) in a confined space may displace enough Oxygen from the environment to cause an unsafe Oxygen level.
An intelligent engineer following best practices will perform confined space entry techniques using a pumped gas detector with either a sampling probe or sample hose to determine safe levels of breathing prior to entry. The engineer should continue to wear a portable gas monitor throughout maintenance work to alert them to any dangers that may arise.
Due to the limited space within the wind turbine, a portable gas detector is the most suitable form of gas detection in terms of usability and cost. The portability of a gas detector allows the engineer to perform gas detection at various points within the wind turbine. Wind farm sites are often remote or offshore so mains supply electricity may not be possible. Therefore a battery powered gas detector must be used. A fixed gas detection system means that it would require sensors positioned at numerous points but due to the small compartments, a fixed gas sensor installation may not be possible.
A portable four-gas detector (also known as a confined space detector) is the instrument of choice for wind tower engineers because it can warn of the multiple gas threats posed by confined space entry. It will detect toxic gases in parts per million (ppm) levels and combustible gases at the lower explosive limit (LEL). A standard four-gas detector will include sensors for monitoring Oxygen (O2), combustible gases, Carbon Monoxide (CO), and Hydrogen Sulphide (H2S).
H2S is heavier than air and can accumulate in the basement and other areas underneath the turbine. One of the dangers of being exposed to H2S can result in olfactory fatigue. The characteristic “rotten egg like” odour can be detected by smell at lower levels but only for a short duration. This results in a normal but temporary inability to pick up a particular smell after being exposed to it for a long time, leaving the engineer unaware of the potential dangers. At higher levels, the gas can cause dizziness leading to unconsciousness.
Methane, the primary component of natural gases, is a combustible gas, often found in confined spaces. Produced by leaks in pipelines, Methane, along with Propane and other combustible gases, must be monitored with a combustible gas sensor that gives an alert at the LEL. A standard four-gas portable detector is equipped with a combustible gas sensor.
Carbon Monoxide, a by-product of the incomplete combustion of hydrocarbon compounds, can be found where any gas-powered equipment is used.
Oxygen levels must be determined prior to entry of a confined space. Oxygen can be consumed by oxidation from rusting equipment, bacteria growth, displacement by another gas, or rotting vegetation. Oxygen sensors are included in a standard four-gas detector.
Many portable gas detectors are designed for simple ease of use and to provide an alarm. Alarms vary; audibly (a loud siren), visually (flashing lights), or tactilely (through vibration). Engineers will be able to quickly react to emergency alarms. Superior gas detector models may offer additional details, including large, backlit displays and oversized, heavy-duty buttons. These features help the user operate and view gas readings in misty, wet or dark conditions. Verify whether the unit logs standard data, as well as event and calibration data that can be uploaded onto a computer software program in case the data must be retrieved. Check the battery power too and how it can be re-charged. Portable gas detectors may only hold a battery charge for 8-12 hours (over a working shift) so will need to be re-charged. For maintenance engineers that are field based, in-vehicle chargers are handy so that the gas detector can be re-charged whilst driving between jobs.
a1-cbiss recommend the following portable gas detectors:
The PS200 from GMI is our best selling four-gas detector.
The PS200 has a rugged and quality feel to it and more so once a protective, rubberised and coloured boot has been fitted. The PS200 is IP67 rating meaning that it’s dust-tight and waterproof to 1 metre. The PS200 features an optional internal pump which can be easily switched on to carry out pre-confined space entry testing.
A lithium-ion battery provides run time of up to 80 hours* when using the low power LEL sensor (however, this needs to bought as an extra). Re-charging the battery only take 4 hours and you can expect an 80% charge within 2 hours of recharging which is a major benefit when the gas detector is in frequent use.
The PS200 gas detector comes with data logging as a standard feature. With a memory capacity up to about a year, the PS200 can record everything. Including when it goes into alarm, through the session log feature.
Do you work maintain wind turbines and need a confined space detector? Contact a1-cbiss to arrange a site survey or talk to our technical specialists for help with your gas detection needs