Some Engineering terms

pH: The hydrogen ion concentration of a solution expressed in a manner which gives a scale value of 7 for pure water, value above 7 are alkaline & less than 7 are acidic.

pH value range from 0 to 14, pH value governs the degree of corrosion. 

Ogee ring: ''Ogee'' ring is a thicker plate which isolates the shell from the furnace.

Tell tale hole:

Orifice plate: A thin circular plate with an axial hole. It is fitted into a pipe line in order to enable a differential pressure measurement across it. This differential pressure is then used to measure the liquid flow rate through the pipe. 

Entropy: An aspect of a substance, which will increase or decrease, as the substance receives or rejects heat. 

Enthalpy: A thermodynamic property of a fluid which is equal to the internal energy plus the product of pressure and volume at constant pressure.

Enthalpy = Internal energy + Work done 

latent heat: Heat added or removed from the body to change the state without changing the temperature. 

Humidity: A measure of the amount of water vapour in a given volume of gas.

Relative humidity: It is the ratio of % of water vapours in air to the % of water vapours in saturated air at the same temp.

R.H = % of water vapours in air / % of water vapours in saturated air 

Specific Humidity: It is the ratio of the mass of water vapour to the mass of dry air in a given volume of mixture.

Sp. H = Mass of water vapour / Mass of dry air  

Halon: A halogeneted hydrocarbon gas which is used as a fire extinguishing agent. Two examples are Halon 1301 (BTM) and Halon 1211 (BCF). 

Psychometric chart: This chart show the relation between temperature & relative humidity. 

Mono pump: It is a single screw pump. It consists of corrosion resisting rotor and a stator of natural or synthetic rubber. It has small capacity & smooth flow. 

Pitch: If the propeller is assumed to work an unyielding fluid, then one revolution of  that shaft, then propeller will move forward a distance which is known as pitch. 

Drooping clearance: The clearance between the stern tube & tailshaft is called drooping clearance.

Measure by - poker gauge 

Lignum Vitae: A hard wood which is used as a lining for stern bearing. It lubricated by S.W but subject to some swelling. 

Follow up system: The angle amount of the rudder turns is dependent upon the amount of steering wheel. 

Non Follow up system: The rudder will move as long as the control is held in an actuating position & will stop when it is moved back to off position. 

Jumping clearance: The clearance is provided for the free up & down movement of the rudder. 

Buffer spring: The buffer spring in the hunting gear, linkages is provided to take up any excess movement beyond the maximum stroke of the pump. 

Telemotor: Telemotor system is used for sending signal from the steering wheel to the actuating system that controls the rudder. 

Poly Electrolyte: It is the synthetic organic polymer of high mole water weight which is used in boiler & FWG to prevent scale formation. 

FWG P. E. Dosing rate - (2-8 ppm) 

Demister: Demister is a mesh type layer of knitted molten metal which is used to improve the purity of distilled water. 

Octane Number: Octane Number measures the knock rating of the fuel combustion in the engine. 

Cetane Number: Cetane Number indicates the ignition quality of the fuel.

The higher Cetane Number causes for shorter ignition delay. 

Calorific value: It is the amount of heat produced by complete combustion of one unit mass of fuel. 

Pairing Disc: Pairing disc is a stationary impeller mounted in a chamber at the neck of the bowl.

Its function is to convert the rotating energy into pressure head. It is one kind of centripetal pump. 

Puncture valve: It is a device to positively stop the engine, irrespective of the rack position.