MEOclassIIexamnotes

A hydrostatic release unit allows a liferaft to launch automatically if there isn’t time for crew to launch it manually.  How it works: The strong white rope is secured to the deck or liferaft cradle and attached to the liferaft lashing with a sliphook.  If the ship sinks, the water pressure will (within 4 metres) activate the sharp knife which  cuts the white rope and the liferaft will float free.  As the ship sinks, theliferaft painter line will be stretched and the liferaft starts to inflate.   The Red Weak Link breaks and survivors can board the floating liferaft. • Breaking strength of white rope sling: min 15kN. • Breaking strength of red weak link: 2.2 +/- 0.4 kN

 Advantages  Lower frictional drag than traditional packing means improved pump efficiency A mechanical seal will not wear out a shaft, or sleeve, as fast as packing rings Near zero leakage is possible with mechanical seal; packing requires some leakage (usually visible) for proper lubrication Properly applied mechanical seals require less periodic maintenance than packing Specially designed mechanical seals can be applied to higher pressures and speeds than traditional packing.  Disadvantages   Less tolerant to shaft deflection and misalignment    Less tolerant to dirty or contaminated liquid; will require cyclone separator to clean the liquid  Require expensive seal piping to flush and quench   Mechanical seals are more expensive than packing rings

There is only coil ( capillary tube in refrigerator ) which maintains freezer temp. The refrigerator chamber is maintained using forced circulation method by a fan which uses this cold air to cool the other chamber. Or no fan is used and convectional currents gets set in due to temp difference between the freezer and refrigerator section .Thereby having two temp in refrigerator

1.Reduce max working pressure of boiler 2.Change the safety valve to larger size diameter  If you change the safety valve then need to increase corresponding waste pipe dia and also safety valve cut chest cut size need to be increased Option 2 is bit complicated so we go for option 3. 3.Reduce the firing rate by following   Change the nozzle Dp transmitter need to be recalliberated Steam cut in/ cut off will as per new max working pressure Set the safety valve for new max working pressure Accumulation pressure test to be done in presence of surveyor

In air compressor their is no diffential pressure means air is taken from outside through suction filter . While in refer compressors they take suction through the crankcase having suction pressure of vapour coming from the evaporator so they use diffential pressure switch

The Portion of the volute that extends closest to the Impeller is called cutwater. So the clearance between the Vane and Cutwater portion of casing at the discharge is known as cutwater clearance Some of the liquid passes the cutwater and stays inside the pump for another trip around the volute. However, most of the liquid passes the cutwater and decides to exit the pump through the discharge nozzle.

Thermal insulation must be fitted to refrigerated cargo tanks for the following reasons: • To minimise heat flow into cargo tanks, thus reducing boil-off. • To protect the tanker structure around the cargo tanks from the effects of low temperature.   Insulation materials for use on gas carriers should possess the following main characteristics: • Low thermal conductivity. • Ability to bear loads. • Ability to withstand mechanical damage. • Light weight. • Unaffected by cargo liquid or vapour.