Hydraulic Operation of Emergency Systems

Hydraulic Operation of Emergency Systems

Maintaining continuous power supply on board is one of the most important tasks during navigation. However, unavoidable accidents sometimes occur and the power supply of the ship may be interrupted due to mechanical failure, technical failure, etc.

In this case, emergency equipment such as lifeboats and navigation lights must be in normal working condition so that they can be used in emergency situations. As we all know, ships are built in accordance with the regulations of the International Convention for the Safety of Life at Sea (SOLAS) and the International Maritime Organization (IMO), and all necessary regulations established by SOLAS and IMO must be followed during the construction of ships.

In the event of a power failure, an automatic backup power supply must be provided. Batteries and emergency generators provide this backup power supply to power important equipment. Since batteries cannot supply power for a long time, emergency generators are used first.

Understanding the emergency power supply system

According to SOLAS regulations, emergency power supply equipment must resume operation within 45 seconds after a power failure. During a power outage, the emergency generator is usually driven by a small electric motor. The power for this motor comes from the batteries charged by the emergency switchboard. If the equipment or emergency generator cannot be started for any reason, an alternative method or manual starting must be provided.

According to the International Convention for the Safety of Life at Sea ( SOLAS ) regulations, the alternate starting method must be able to provide three additional starts within 30 minutes.

Hydraulic starting is the most common method for starting emergency generators. In addition to hydraulic starting, other methods include:

1) Compressed air .

2) Inertia starter.

3) Manual starting.

Composition and working principle

The hydraulic starting system uses hydraulic and pneumatic principles to first store energy and then provide or release energy to start the engine.

Top 10 Best Mining Ships in the World

What Are The Common Types of Valves on Ships?

Dredgers Ships: Types & Their Uses in Offshore Operations

Complete Guide to Marine Engineering

The main components of this system include:

1) Oil supply tank and hand pump

The oil supply tank provides hydraulic oil, and the hand pump pumps the hydraulic oil to the accumulator to help start the engine.

2) Hydraulic accumulator

This is the most important component of the system because it is the heart of the system and the energy is stored here. It consists of a cylinder with a sliding leak-proof piston inside. Above the piston, the cylinder is pre-filled with nitrogen at a pressure of about 200 bar. The oil pressure acts on the piston and the required oil pressure is stored in the accumulator.

3) Pressure gauge

Pressure gauge is used to measure the pressure in the accumulator .

Hydraulic operation of the emergency generator

4) Relay valve lever

Operating this lever releases the energy stored in the accumulator to the starting device.

5) Starting the device and engine dog

The starting device is connected to the free end of the engine through a bracket, while the engine dog is connected to the engine crankshaft through a suitable adapter. The starting device consists of two opposing cylinders and a rack and pinion system. One end of this system has teeth that drive the dog with opposing teeth.

Two helical grooves are formed in the circumference of the gear and are held in place by a spring ball in the drive housing, which helps to lock and unlock the gear by axial movement. The helical tooth profile of the gear and rack allows positive locking.

How to operate the hydraulic starter?

1) Check that all fuel valves, cooling water valves, etc. of the generator are open.

2) Check the oil level in the supply tank. Top up if necessary. Note that if the oil level in the pressure gauge is low and the accumulator pressure is within the manufacturer's recommended range, do not top up the tank oil because the oil will flow back to the starter after starting.

3) Check the accumulator pressure. Increase the pressure if necessary. Adjust the accumulator pressure according to the manufacturer's recommendations.

4) Operate the relay valve stem. The relay valve stem operates in two stages. Turn the relay valve 45 degrees; in this position, you will feel resistance. In this stage, oil is slowly pumped into the actuator, causing it to rotate slowly, engaging the claws. When the claws are engaged, fully engage the control lever. This will release the pressure in the actuator and start the engine.

Avoid sudden vibration of the relay lever to prevent damage to the gear and clutch system.

5) When the engine begins to rotate, release the control lever, which will return the control lever to the normal position. After the engine starts, the oil used to drive the engine will return to the supply tank.

6) Check the accumulator pressure. This pressure should be sufficient to support two more starts.

7) Increase the pressure again for the next start.