P-Alkalinity and T-Alkalinity

P-Alkalinity:
Phenolphthalein is less alkaline than hydroxides or carbonates, and when it is
added to a sample containing hydroxides and or carbonates it will first neutralize the
hydroxides forming salts, it will turn pink in color. The acid used after this coloration will first neutralize the hydroxides forming salts, it will then react with the carbonate molecules
present forming bicarbonate molecules. Bicarbonate molecules are less alkaline than
phenolphthalein, hence, the pink coloration disappears once all the hydroxides and
carbonates have been dealt with by the acid. One bicarbonate molecule is formed from two
carbonate molecules, hence in the test the quantity of acid used is a measure of the
alkalinity due to the hydroxides (caustic) present and half the carbonates.

T-Alkalinity:
Methyl-orange indicator is less alkaline than phenolphthalein and bicarbonates.
It can be used initially in place of phenolphthalein or in continuation after the alkalinity to
phenolphthalein test. If no yellow coloration results when the methyl-orange is added to the
alkalinity to phenolphthalein sample no bicarbonates are present. Hence no carbonates are
present. Therefore, the alkalinity as determined in the alkalinity to phenolphthalein test has
been due to hydroxides alone.

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Differences between MC/MC-C and ME/ME-C engines

The electrohydraulic control mechanisms of the ME engine replace the following components of the conventional MC engine: Chain drive for camshaft Camshaft with fuel cams, exhaust cams and indicator cams Fuel pump actuating gear, including roller guides and reversing mechanism Conventional fuel pressure booster and VIT system Exhaust valve actuating gear and roller guides Engine driven starting air distributor Electronic governor with actuator Regulating shaft Engine side control console Mechanical cylinder lubricators. The Engine Control System of the ME engine comprises: Control units Hydraulic power supply unit Hydraulic cylinder units, including: Electronically controlled fuel injection, and Electronically controlled exhaust valve activation Electronically controlled starting air valves Electronically controlled auxiliary blowers Integrated electronic governor functions Tacho system Electronically controlled Alpha lubricators

Why is a man hole door elliptical in shape?

Any opening in a pressure vessel is kept to a minimum and for a man entry an elliptical hole is lesser in size than the corresponding circular hole. More over it is prime concern to have a smoothed generous radius at the corners to eliminate stress concentration. Hence other geometrical shapes like rectangle and square are ruled out. To compensate for the loss of material in the shell due to opening, a doubler ring has to be provided around the opening. The thickness of the ring depends on the axis length along the dirrection in which the stresses are maximum and the thickness of the shell. It is important to align the minor axis along the length of the vessel, as the stress in this direction is maximum. Longitudinal stress: Pd/2t where P= pressure inside the vessel, d= diameter of the arc, t= thickness of the shell plating Circumferential stress: Pd/4t More over a considerable material and weight saving is achieved as minor is along the direction of maximum stress.

Shell Expansion Plan

It is a two dimensional drawing of a three dimensional surface of the ship’s hull form. This plan is very useful for the following information:It is used for marking the location of a hull Damage on this plan by identifying the strake number , letter and frame number so that the exact location of the damage and also suggested repairs are marked in a localised copy. The shell expansion can be used for finding areas of painting surfaces such as topside, boot topping and bottom areas by applying Simpsons rules directly. In the shell expansion the vertical scale used is different from the horizontal scale and a suitable adjustment has to be made when calculating areas. This becomes useful in solving disputes concerning areas of preparation and painting. It gives information on the thickness of the original strake which is indicated by the number in the circle shown in the strake. The quality of steel used is also shown by letters A,B,D E and AH, BH,DH, EH.

MEOclassIIexamnotes

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