What causes a crankcase explosion?
Under normal circumstances, the air in the crankcase will contain droplets formed by lubricating oil splashing from the bearings and impinging on moving surfaces. If a hot spot develops and the oil mist reaches a certain concentration, it will be ignited and a primary explosion will occur.
What is crankcase explosion in marine diesel engine?
What is crankcase explosion? It is an explosion that occurs in the crankcase because of the mixture of oil mist and air in the ratio that is within the range of flammability. In addition there must be a source of high temperature energy sufficient to initiate combustion. This source is called hot spot.
How do you prevent a crankcase explosion on a ship?
There should be adequate cooling of the engine. Proper purification and analysis of lube oil. Lube oil filter to be changed over & cleaned as per schedule. Ensure proper cylinder lubrication by checking the condition of piston, piston rings and liner through scavenge ports.
What causes crankcase explosion diesel?
Crankcase explosions are also the result of high operating temperatures of the engine. The main cause of crankcase explosions are the development of hot spots at various places in the crankcase. Due to the reciprocating motion of the piston the lubricating oil in the crankcase is splashed in the air.
In which of the following engine crankcase explosion occurs?
Crankcase explosion in I.C. engines usually occurs as First a mild explosion followed by a bi explosion. Crankcase explosions are also the result of high operating temperatures of the engine. The main cause of crankcase explosions are the development of hot spots at various places in the crankcase.
What is primary and secondary crankcase explosion?
Secondary explosion The primary explosion produces a shock wave which propagates inside the crankcase with increasing speed and distance traveled. This shock wave has a breaking effect which further reduces the size of oil droplets, producing more fuel for ignition.
How do you put out a crankcase fire?
For Major Fire
- Stop the engine immediately.
- Engage the turning gear and start turning the engine to prevent the seizure of significant components.
- Attempt to extinguish the fire with the fixed fire fighting system or the.
In which of the following engines crankcase explosion occurs?
What should I check during crankcase inspection?
The inspection of crankcase should be done periodically to check the following:
- Connecting rod play in the crank pin.
- Lube oil condition.
- Flow of lube oil.
- External condition of crank pin and main bearings.
- Locking arrangement of main bearing bolts and connecting rod bolts.
What is hot spot in marine engine?
Hot spot is nothing but the heat source produced as a result of rubbing between two metal surfaces or friction between two metals parts such as piston rod and gland, cross head guides, chain and gear drive etc. The hot spot is generally caused by improper maintenance and insufficient or less clearance.
What do you mean by secondary explosion of an engine crankcase?
This new air and new supply of fuel produced after first explosion comes in contact with hot spot, causing another explosion, which is extremely severe as the amount of fuel is high now. This explosion is known as secondary explosion and it causes very severe damage to engine plating.
What are crankcase safety devices?
Crankcase Safety Devices. There are various safety devices such as the crankcase exhaust fan, relief valve, bearing temperature sensor, breather pipe, oil mist detector, lube oil temperature sensor, and alarm. Together they play an active role in the safety and protection of the main engine from the crankcase explosion …
What is crankcase explosion on ships?
However, it’s not just the fuel tanks that are probable source of fire and explosions but even the machinery that uses fuels. In this article we will learn about one such explosion, which is supposed to be known as the most disastrous explosion and one which takes place in the ship’s main engine. It is called the crankcase explosion.
What does a crankcase warning notice mean?
This warning notice is to specify that whenever overheating is suspected in the crankcase, the crankcase doors or sight holes are not to be opened until a reasonable time has elapsed after stopping the engine, sufficient to permit adequate cooling within the crankcase. Crankcase Access and Lighting
What are the safety features provided on the crankcase?
In a main engine crankcase also there are safety features provided to detect the causes of explosion. There are two main features provided on the crankcase to prevent crankcase explosion. They are as follows: 1. Oil Mist Detector
What is the crankcase relief of a small engine?
The internal combustion engine of cylinder diameter of 200 mm or a crankcase volume of 0.6 m3 and above shall be provide with crankcase relief valve of a suitable type with sufficient relief area. In small engine, cylinder diameter not more than 300mm, crankcase door of which are usually very strong. It may have relief valve or valves at its end.