[ID] => 10098
[post_author] => 5714
[post_date] => 2018-09-17 09:38:31
[post_date_gmt] => 2018-09-17 08:38:31
[post_content] => Diesel engine runaway is a dangerous phenomenon where the running engine draws extra energy from low concentrations of any hydrocarbons in the surrounding air. This causes uncontrolled overspeed beyond the safe limits and an explosion or ignition of the external air-fuel mixture.
A fatal accident at ICI Wilton in the UK in 1969 led to increased general awareness of diesel engine runaway in the oil and gas industry. Based on an Esso Research patented original flow operated solution, Chalwyn created its automatic D valve in 1972 to overcome this problem. Esso Fawley refinery required installation of these safety valves for vehicles and machines working at the UK site.
Gasoline engines and diesel engines do not operate the same way. A gasoline engine is generally fed by a carburettor and butterfly valve where the volume of air-fuel mixture taken into the engine is controlled by the accelerator pedal, which subsequently controls engine speed.
A diesel engine’s speed, however, is controlled by the air-fuel mixture happening in the combustion chamber. Diesel engines use a ‘direct injection’ method with no need for butterfly valves to manage air flow. Since no air restriction is present in a diesel engine, it means that an unlimited air supply is possible.
Diesel engine runaway can be caused by several variables; however, one common cause is the engine drawing in external hydrocarbons that have leaked into the atmosphere.
Accident history has shown that diesel engines are a potential source of ignition in areas processing oil and gas. Airborne combustible hydrocarbons can blend with the air causing an additional supply of energy that is consumed by the running diesel engine. Since diesel engines control fuel and not air, the engine can no longer maintain speed control and at low concentrations the extra energy is sufficient for the engine to accelerate uncontrollably.
Turning off the ignition key or fuel supply will not stop this process and the engine will continue to accelerate beyond the red line and normal safe limits. Only fitting an emergency shut off valve in the engines air intake system will prevent the overspeed by stopping the engine at a pre-set limit
Incidences of damage from diesel runaway by consumption of the lubricating oil were seen and understood in earlier times, but these rarely resulted in loss of life. However, in the late 20th century, the accident investigations and improved safety standards led to requirements for automatic engine shutdown devices in several regions for offshore oil and gas operations. Unfortunately, the awareness and local regulations varied internationally, so engine-related accidents have since continued in both ‘upstream’ and ‘downstream’ petrochemical activities.
In Texas in 2003, two workers were killed and two more were injured when a vapour cloud from the cargo was drawn into the intakes of two idling vacuum trucks. In 2005 a US refinery explosion was ignited by a runaway diesel pickup; 15 people died and 170 were injured in the blast.
In 2010, an offshore rig explosion killed eleven people and created the largest accidental oil spill in history. A diesel engine runaway in the engine room is considered one of the main contributing factors.
Most tanker trucks carrying hazardous materials use diesel engines, making this already dangerous problem into an extremely dangerous one in the event of a flammable liquid or gas leak. Loading and unloading of flammable and combustible liquids is one of the most hazardous operations likely to be undertaken at any manufacturing or storage facility. Tankers transporting highly flammable liquids are a top concern; diesel engine runaway can cause explosions if not prevented.
In any instance, the drivers of these vehicles are likely to be innocent victims of an accident involving diesel engine runaway and it is the fleet operator’s duty to make sure all risks have been considered when working in hazardous areas and all safety precautions are in place.
With increased awareness has come regulatory reform. Transport Canada have taken a pro-active approach and passed a new law that requires automatic air intake shut-off devices to be fitted on all diesel engines. Compliance with this law took effect on 12 January 2018 and it is recommended that operators review safety policies and follow suit
[post_title] => Diesel runaway: Stick to the speed limit
[post_status] => publish
[comment_status] => open
[ping_status] => open
[post_name] => diesel-runaway-stick-to-the-speed-limit
[post_modified] => 2018-09-14 18:42:17
[post_modified_gmt] => 2018-09-14 17:42:17
[post_parent] => 0
[guid] => https://www.hcblive.com/?p=10098
[menu_order] => 0
[post_type] => post
[comment_count] => 0
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Diesel runaway: Stick to the speed limit
Diesel engine runaway can have fatal consequences for companies involving in manufacturing, handling or transporting hazardous materials