PURIFIERS IMPORTANT POINTS IF DO IS TO BE PURIFIED IN A HFO PURIFIER, WHAT SIZE OF GRAVITY DISC WILL BE CHOSEN ? Over flow reasons HEAT EXCHANGERS WHAT PROVISION IS GIVEN FOR EXPANSION OF TUBES IN SHELL AND TUBE TYPE HX? Why purging vent is required? What happens if air is in? PLATE TYPE HEAT EXHANGER DIS ADV REFREGIRATION THERMOSTATIC EXPANSION VALVE REF USED ONBOARD NOW A DAYS ? HOW IS OIL DRAINED BACK TO THE COMPRESSOR FROM EVAPORATOR? Refer comp

- Running hot - Suction side frosting - Temp disch high – reasons ?

REFRIGERANT PROPERTIES REFER LUB OIL PROPERTIES AIR IN THE SYSTEM Ref temp over charge and under charge What s the use of injection valve In hermetic compressors GENERAL DIFFERENCE BETWEEN OIL SEAL AND MECH SEAL DIFFERENCE BETWEEN SAFTEY AND RELIEF VALVE WHAT IS RESONANCE ? i.e. why ship vibrates heavily at critical rpm ? WORKING OF SALINOMETER Work hardening Nitriding Annealing and normalising – diff ICCP COMPRESSORS SPECS WHY SRPING PLATE VALVES ARE PREFFERED DIFFERENCE „S BETWEEN REFER COMP AND AIR COMPRESSORS SAFTEY DEVICES

OXYGEN ANALYSER COMBUSTIBLE GAS METER OR EXPLOSIMETER TANK SCOPE

- DIFFERENCE B/W TANK SCOPE AND EXPLOSIMETER? PUMPS SUBMERSIBLE PUMPS (FRAMO) SEWAGE TREATMENT PLANT INCINERATORS FRESH WATER GENERATOR

- SPECS

GENERAL DIFFERENCE BETWEEN OIL SEAL AND MECH SEAL

OIL SEAL MECH SEAL

STERN TUBE LIP SEAL PUMP GLAND SEAL

Sealing Directly in contact with the shaft

Sealing not in direct contact , its in contact with mating surfaces

Garter spring provided to increase the snapping force on the shaft

Axial spring is provided held in tension by a grub screw

Probability of leaking is high Good integrity of sealing

Renewal is easy Difficult as the whole pump has to be dismantled

Cheap Costly

Less life compared to mech seal Better life provided there is no dust inclusions

WHAT IS RESONANCE ? i.e. why ship vibrates heavily at critical rpm ? When the frequency of the oscillation of m/e matches with the hull’s natural frequency of

vibration, then the vibration is amplified - this is called resonance WHAT ARE THE DIFFERENCE BETWEEN PIPE THREAD AND BOLT THREAD ?

- A straight thread is the thread you would find on a bolt and nut. - A tapered thread is the thread you would find on water/gas pipe connections. - A tapered thread is a sealing thread. - A straight thread is an axial load bearing thread.

CLEARANCES TAKEN AFTER GEAR PUMP OVERHAUL End Clearance

- Distance measured between rotor and pump cover face. Total end clearance is thedistance measured either side of the rotor and added together. Diametrical Clearance Distance measured around outside diameter of rotor and the inside diameter of body face.

HOW TO CARRY OUT DYE PENETERANT TEST? - The surface is cleaned and the low viscosity penetrant (dye) sprayed on. - After a set time the surface is again cleaned. A developer is then used which coats the

surface in a fine white chalky dust - The dye seeps out and stains the developer typically a red colour.

HERE IS ONE MORE NDT METHOD MAGNETIC CRACK DETECTION...

- A component is place between two poles of a magnet - The lines of magnetism concentrate around flaws. - Magnetic particles are then applied, in a light oil or dry sprayed, onto the surface where

theyindicate the lines of magnetism and any anomalies. LIMITATIONS

- Firstly it cannot be used on materials which cannot be magnetised such as austenitic steel and non-ferrous metals.

- Secondly it would not detect a crack which ran parallel to the lines of magnetism.

HOW KEYLESS PROPELLERS DONT SLIP, WHAT PRINCIPLE

- The concept is same like tightening ur main engine tie bolts. - The stern shaft is expanded hydraulically - and propeller is pushed in using hydraulic too.

The reason they don‟t slip is becoz :

- the force exerted by water on propeller is way less than the hydraulic pressure the propeller fitted in.

- tensile and compressive hoop stresses are created along the mating surface of the bush of propeller...hence the surface transmits the torque !!

HOW TO REMOVE A BROKEN STUD

- Stud extractor - Drilling and tapping - Welding a nut on it

THIS IS STUD EXTRACTOR ! NOW, YOU WOULD‟VE STUDIED WHAT S MUFF COUPLING ! – IF SURVEYOR ASKS YOU WHAT S THE ULTIMATE ADVANTAGE BENIFFITED OUT OF IT , WHAT WOULD YOU SAY?

- If muff coupling is not fitted, then imagine your coupling a normal bolted one ! - Now, in the dry dock, it s required to take out the prop shaft to check for trueness

If so, this is what has to be done

- Take out the prop first ! - Come inside e/r , remove the coupling bolts - Then CUT THE SIDE SHELL OF YOUR SHIP AND THEN TAKE IT

NOW, when muff couplings are used

- “U NEED’NT CUT THE SIDE SHELL ! ., - ONCE THE COUPLING IS REMOVED , THE SHAFT CAN BE DRAWN OUT VIA THE

STERN TUBE ITSELF ! WORKING OF SALINOMETER

- Pure water is an insulator - If salinity increases its starts conducting current - If current increases – salinity increases - This increase in current will provide enough power at 2 to activate alarm - And will also short the milli ammeter so that the high current will not spoil the meter

Temperature is directly proportional to conductivity

- Therefore if temp increases the mercury would shut the current proportional to the temp WORK HARDENING

- This is a natural process – due to prolonged working of metals, the inner crystalline sct automatically gets dislocated resulting in increasing hardness and reduced ductility

- Because of the dislocation of internal grain sct, stresses will be developed in the metal and would soon lead to failure

- Eg: Chain blocks, wire slings etc

NITRIDING

- This is just a process of increasing the hardness - A steel would be nitrided to have good strength, good fatigue resistance, good corrosion

properties , to withstand high temp , to withstand EROSION - That’s why mainly used – pump plungers , barrels etc

Working

- Steel is heated aroung 700’c - And introduced in an environment containing Ammonia (NH3) , - Thus induction of nitrogen on the steel surface is carried out - This is called Nitriding

Advantages

- No change in shape after this process - No machining required

NORMALIZING - This is used in eliminating internalstresses or residual stresses in materials - Materials which have undergone forging, or welding or fabrication would be internally

stressed, to relieve this normalising is done - The material is heated up to 900’c - And held in that temp for some time - Then let it cool in still air ( still air cooling enables faster cooling which slightly hardens

the material thus reducing the ductility) - This Increases the Strength and Decreases Ductility

(annealing = Decreases strength – increases ductility : to enabling machining of the product)

Normalising done on Bed plates , Crank shaft after forging etc (i.e. stresses are relieved ) ANNEALING

- This is done to enable machinability in a material

- The material is heated above its critical temp around 900’c - Held in that temp for a while - Cooled down very very slowly. This slow cooling of the material softens it increasing the

ductility and decreasing its strength - Once annealing is done, the material is good enough to be cold worked rather heating to

forging temp ICCP (ref samath sir’s notes) Electro chemical potential

- Mg 1.48 V - Zn 1.01 V - Al 0.75 V - Fe 0.61 V - Cu 0.36 V

Advantages of zn over ICCP

- No electric power - Initial cost low - No complexity - No calibration - No maintenance - No requirement of qualified personnel

Disadv

- Once in two years, should be renewed - Increases the hull resistance - Poor zinc anodes would lead to corrosion of hull

ICCP

- The naturally occurring galvanic corrosion is stopped by - Making the hull Cathode - Electrons are made to arrive at the hull, thus hull doesn’t loose its electrons - The electrons are fed via platinised titanium

Working

- The platinised titanium plates are fitted at strategic locations on the hull - It s completely insulated from the hull - A dc is provided to it - Two reference zinc anodes are also deployed - The rate of electron dissipation of zinc anodes are sensed and a feed back is sent to the

control unit - The control unit automatically regulates the current to the platinised anodes after

transformation(440 v to 24 V) and rectification ( ac to dc) The control equipment auto monitors the amount of current required based on

- Sea water temp - Salinity - Paint thickness of the hull - Ships speed

Typical anode current New ships: 10 to 40 mA / m2

Old ships : 100 mA/m2 to 150 mA/m2 (for bare steel surface)

ADVANTAGES

- DOESN’T DECREASE THE HULL RESISTANCE

- Dry dock interval can be increased - No need of frequent changing of

anodes

DIS ADVANTAGES

- Continuous monitoring is required - Electric supply required - By mistake if reverse connections are

given, corrosion is fatal - Increased current will destroy the

paints in the hull

Note: ON BALLAST TANKS IN TANKERS, ALUMINIUM ANODES will never be used , only zinc will be used , this is becoz if aluminium falls on steel surface, it creates SPARK !!!!

PURIFIERS DISC STACK

- The small chock’s are given to maintain spacing b/w other discs - Smaller the disc spacing, better is the purification - The bottom of those discs are highly polished, so that the sludge easily slips away

IF SAFTEY DATA SHEET DOESN’T GIVE PURIFICATION TEMP

- DO : 20 ‘c - MDO: 40’c - LO: 90’c - LO(high density): 95’c - HFO: 98’C

IF DO IS TO BE PURIFIED IN A HFO PURIFIER, WHAT SIZE OF GRAVITY DISC WILL BE CHOSEN?

- HIGH DENSITY – this will move the interference layer out - therefore smaller gravity disc - DANGER: OVERFLOW, LOSS OF OIL

- LOW DENSITY – Interference layer will move inwards towards disc stack - therefore increase the gravity disc size - DANGER: MIXING OF WATER IN CLEAN OIL OUTLET

HOW IS PURIFIER OVERFLOW SENSED?

- A pressure switch in the clean oil is present - As when the interference layer is broken and oil starts oozing out via the dirty water

outlet(or overflows) the pr in the clean oil outlet will be decreased - This pr difference is sensed and an alarm is raised - Eventually feed will also be shut

TOO MUCH OF FRICTION PADS/ CLUTCH SHOES- WHATS THE PROB?

- Less winding up time would result in increased wear rate on the worm wheel NOTE- DO NOT REPLACE INDIVIDUAL FRICTION PADS, CHANGE IT AS A SET PURIFIER MOTOR

- During winding up time, twice the current is consumed - Thus OVERLOAD trip is not implemented - But a thermistor is deployed- temp increase – trip motor

MOTOR SPEED, 3500 = BOWL SPEED, 11,500 Approximately BOWL SPEED IS 3 times the MOTOR SPEED WORM AND WORM WHEEL are separately available for 50 hz and 60 hz

- If 50 hz spares are fitted for 60 hz supply – DANGER ON OVER SPEED - WORM WHEEL DRIVES WORM, that’s one reason the tooth load is very high

LUB OIL VISCOSITY @ 40‟C ALPHA 220 = 220 Cst @ 40’c Just for more info

SAE 30 (M/E CC) = 108 Cst @ 40’c SAE 40 (AUX CC) = 142 Cst @ 40’c WHAT HAPPENS IF HIGH VISCOSITY(220 CST) LO IS USED INSTEAD OF LOW VISCOSITY(100 CST)?

- Would result in lack of lubrication - Coz cannot penetrate Eg - BELT DRIVEN: 100 CST / FRICTION CLUTCH DRIVEN = 220 CST

COLOUR OF LO DARK – HFO LEAK MILKY – WATER LEAK PURIFIER OVER FLOWING

- High through put

- Operating water tank empty

- Main seal ring improper

- Very high fuel oil temp

- Very low fuel oil temp

- Low rpm (friction pads worn out)

- Excessive vibration ( increased sludge accumulation, bowl nut not tightened properly etc)

- Pilot valve not closed

- Increased sludge in the bowl

- Improper gravity disc selection

- Sealing water failure

HOW DAMPING IS PROVIDED?

VERTICAL SHAFT HORIZONTAL SHAFT

UPPER END - Grooved ball bearing with six damping

springs to take up HEAVY RADIAL THRUST

LOWER END

- A double row angular bearing to take up vertical thrust and

- A Damping spring to dampen the vibrations is provided

- Ball bearings on the either side Support the shaft

HEAT EXHANGER

WHAT PROVISION IS GIVEN FOR EXPANSION OF TUBES IN SHELL AND TUBE TYPE HX? (pg 5 mc George aux)

- The fixed end tube plate is sandwiched b/w shell and water box with joining material - Synthetic o rings for sliding tube plate permits free expansion

Why purging vent is required? What happens if air is in?

- Air in the cooler system will encourage corrosion - And cause air locks decreasing cooler efficiency decreasing cooling area – lead to over

heating That s the reason, purging vents are provided. PLATE TYPE HEAT EXHANGER DIS ADV

- Titanium plates are used – initial high cost - Requirement of long gaskets - Bonding material of the gaskets decide the operating temp - Over tightening of the plates could result in large differential pr - Any leaks is directed to the atm and not on the stream - Cleaning is time consuming - Gaskets are delicate , hence cleaning should be carefully done - Narrow spacing b/w the plates can become easily clogged by sludge and oxide deposits

REFREGIRATION REF USED ONBOARD NOW A DAYS? REF three types

1. CFC 2. HCFC 3. HFC

1. CFC

- ODP/GWP = 1/4000 - Phased out – 1995 - R 11, 12, 113, 114, 500, 502

2. HCFC – GOING TO BE PHASED OUT BY 2020

- R 22 (0.05/1700) - R 123 (0.02/0.02) – Not going to be phased out by 2020, but 2030 going to phased out - R 124 - 401 A - 402 A - 403 A - 405 A

3.HFC

- NOT GOING TO BE PHASED OUT AS PER MONTREAL PROTOCOL - R 125

- R 134 A (0/1300) - 404 - 407 - 410 - 413 - 417 - 507

ODP: OZONE DEPLETION POTENTIAL The potential of a molecule of ref to deplete ozone layer Eg., HFC possess 0 potential where CFC posses 1 , and HCFC – 0.05 GWP – GLOBAL WARMING POTENTIAL

- Measured in terms of 100 years - How much potential the ref have on global warming - Co2 – 1 GWP - Total amount of heat trapped in ref/total amount of heat trapped in co2 for the same

mass THERMOSTATIC EXPANSION VALVE (pg – 352 mc George aux) Function

- Separates high pressure side to low pressure side - Ensure s no liquid stroke to the compressor - Ensure s superheated condition of refrigerant - Keep the evaporator fully active

Working (Ref savant sir diagram and pg 352,353 mg George aux)

- There are three pressures - P1 – actin on top of the bellow - P2 – from the equalising line - P3- spring pressure

- A starved condition in the evaporator would result in greater superheat in P1 - This would open the valve further letting more ref in - When does super heat occur? - only after the latent heat transaction has ended

(Just to understand – latent heat transaction meaning – point whr all the liquid ref has evaporated to gas)

- The actual pr at the outlet of evaporator - P2 - The greater pr on the P1 is a result of SATURATED TEMP + SUPER HEAT - This additional pr P1 overcomes P2,3 and ends up opening the valve.

Why equalising valve is required If there is high pr drop across the evaporator then equalising tubes are used

- This line is provided to reduce the pr drop across the evaporator - To avoid starvation of ref in the evaporator

HOW IS OIL DRAINED BACK TO THE COMPRESSOR FROM EVAPORATOR? (pg 347 mc George aux)

- Oil is manually drained from the evaporator - It reaches to thermostatic oil valve - The oil mixed with ref (since coming from the evaporator) is sent to rectifier unit - Rectifier unit – is nothing but a heat exchanger, the oil and ref mixture is heated up by the

hot liquid ref, thus the ref in the oil is vaporised since it is heated to super heat ensured by the thermostatic oil valve

- As when this oil and ref is sent back to the compressor, the oil is drained to cc and ref is sucked by compressor

Why this happens and where?

- When refrigerant has good miscibility (i.e. capability of mixing oil and forming mutual soln), then the oil will be carried over to evaporator and also shall be brought back!

- But if the refrigerant doesn’t have miscibility (eg co2), the system would have oil but not compressor, Thus in refrigeration system with co2 , the oil is periodically drained (manually) via oil rectifier circuit

Refer comp

- Running hot - Suction side frosting - Temp disch high – reasons?

COMPRESSOR RUNNING HOT

- Tev setting not proper(remaining almost closed) - Condenser improper cooling - Crank case lub oil heater not cut off - Air in the system

DISCH TEMP HIGH

- Air in the system - Condenser improper cooling - Tev setting improper - Over charge

SUCTION SIDE FROSTING

- Very low super heat - Tev setting not proper

- Sensing bulb not in contact with the coil - Evaporator heavily fouled / frozen - Fan not running - Excessive sub cooling ( i.e very low s.w temp) - Over charge

AIR IN THE SYSTEM

- Short cycling (icing at the expansion valve) - Discharge pr fluctuates - HP CUT OUT – coz of high disch pr - Bubbles at sight glass - Condenser hot - Refrigeration capacity reduces

REFRIGERANT PROPERTIES

- Non flammable - Non explosive - Non corrosive - High thermal conductivity - Low boiling point - Low freezing point - Low spec vol - High critical temp - High critical pr - Non toxic - Non reactive with oil - Environment friendly - Easy leak detection - Easily available

REGARDING REF LUB OIL There are three types

- Mineral oil - Alkyl benzene - Polyol Esters

or poly alkaline glycols Further info

Lub oil break down temp at exhaust valve s

- MINERAL OIL : 176’C - ALKYL BENZENE: 198 ‘C - POLYOL ETHYLENE : 294’C

REF LUB OIL PROPERTIES – DETAILS GOOD MISCIBILITY AND SOLUBILITY

- To ensure the oil gets back to the cc GOOD CHEMICAL STABILITY

- To ensure, the oil doesn’t react chemically with the ref nor with the materials in the system

HIGH THERMAL STABILITY

- To prevent coking of oil at Exhaust valves due to high temp High Flash point LOW WAX POINT / FLOCC POINT

- At low temp , the oil should form wax - Or else the wax would get cogged in the system

LOW POUR POINT

- Low pour point is required as to ensure, the oil doesn’t adhere itself on to the tubes of the systems but flows freely

GOOD DIELECTRIC PROPERTY

- In hermatic compressors the oil insulates the motor and the compressor body , that s one reason the lub oil is required to have good dielectric property

GOOD COMPATABILITY

- The oil should be compatible with any oil of the same viscosity GOOD VISCOSITY

- The oil should be able to produce good film at high cylinder temps - And should be able to lubricate at low temp as well

NO MOISTURE

- The oil should ensure no moisture content NO CONTAMINANTS

- There should not be any contaminants as well REF LUB OIL PROPERTIES

- Good miscibility and solubility - Chemical stability - High Thermal stability - Low wax point - Low pour point - Good dielectric property – As in hermetic compressors the oil is the insulating material

between the motor and the compressor body - Proper viscosity - No foaming - Good compatibility - High flash point - Oil free of moisture - No contaminants

REFER OVER CHARGE AND UNDER CHARGE OVER CHARGE

- HP CUT OUT - Compressor running hot - Condenser hot - Suction of compressor frosting

UNDER CHARGE

- Short cycling - Temp in the room not able to achieve

Use of injection valve in Hermetic compressor

COMPRESSORS SPECS

COMPRESSOR MOTOR

BORE (1

st/ 2

nd ) 140 / 115 mm

Stroke 100 mm Pressure 25 bar Capacity 125 m3/hr Power 26.8 KW Jacket cooling water 18 lts/min Heat exchange 21,900 Kcal/hr CC lub oil 11.5 lts Weight 420 kgs

Power 30 KW Rpm 1800 rpm 440 Volts 4 Poles Rating – continuous Weight 200 kg approx

AIR BOTTLE CAPACITY 16,600 Lts Working pressure 25 Bar Hydraulic pr tested 37.5 Bar Weight 5000 kg

AIR BOTTLE SAFTIES

- Relief valve - Fusible pulg - Pr gauge - Internal coating (coppal varnish) - Low pr alarm - Drain

WHY SPRING PLATE VALVES ARE PREFFERED (pg 105 devan aranha)

- Increased surface area which enable a large volume of gas exchange - With a very small lift - Hence very less resistance - Low inertia to overcome

DIFFERENCES BETWEEN REFER COMPRESSORS AND AIR COMPRESSORS

AIR REFER

- The compressor doesn’t decide the

capacity of other plant

- Just compresses normal air

- Has inter coolers

- If the end machinery has a problem , wouldn’t bother the compressor

- No heating coil

- Cc breather present

- Suction pr atm bar

- Here the compressor decides the

capacity of AC plant

- Compresses refrigerant to a pressure corresponding to saturation pr which has temp higher than the naturally available cooling resources (like air or water) - coz only then the ref will be condensable by the cooling medium

- Doesn’t require intercoolers

- If any machinery in the system has a problem, then compressor is also in trouble

- CC breather absent

- Pr is 3 bar

DIFFERENCE BETWEEN SAFTEY AND RELIEF VALVE

SAFTEY VALVE RELIEF VALVE

- Set at 3% of working pr - Can be opened manually - Due to popping action, no wire drawing

effect - Here opening is sudden when set

pressure is reached

- Set at 10% of working pressure - Manually cant be worked - No popping action, hence wire drawing

effect can be seen - Valve lift is proportional to pressure

COMPRESSOR SAFTIES

- Fusible plug - Relief valve - Bursting disc - High jacket water temp trip - Water no flow trip - Low lub oil pr trip - Motor overload trip

SAFTEY DEVICES OXYGEN ANALYSER (ref pg 459 Mc George aux )

- Oxygen is paramagnetic (i.e faraday found that oxygen gets attracted to magnetic field) - But the rest of the gasses eg. Nitrogen are Dia magnetic (i.e. they repel )

So this principle is used here Working

- A dumbbell filled with nitrogen is suspended between magnets - Now, this dumbbell would position it away from the mag field as Nitrogen is dia magnetic - This instrument is placed in a place whr oxygen content has to be measured - When sample contains o2 comes in contact with the dumbbell the amount of oxygen

content would increase the mag filed (aiding the magnets- coz, eg, if u magnetise a needle, the needle then itself becomes a magnet)

- Now since this oxygen has increased the magnetic field, the nitrogen sphere would move further away taking a position whr the field is the least

- Thus the amount of deflection is proportional to the amount of oxygen content - Its calibrated to zero position with pure nitrogen and a photo cell is also placed with a

light source - 21% of oxygen is calibrated in normal atmospheric conditions

- When the nitrogen dumbbell deflects due to presence of oxygen the change In voltage of

photocell is recorded and to compensate the change, the compensating current is sent back via feed back circuit

- Thus the compensating current also gives us the oxygen content - The compensating current passes to the device via a meter that is calibrated to give

exact readings Note

- There are other gasses that are diamagnetic too - Eg. Nitrogen di oxide , nitric oxide, Chlorine di oxide etc

COMBUSTIBLE GAS METERS / EXPLOSIMETER (ref pg 461 mc George ) (diagram ref samanth sir’s one) CONSTRUCTION

- A wheat stone bridge is electrically balanced - i.e. no current flows via the circuit - the combustion chamber is ceramic coated - the resistance is catalyst coated in the measuring cell - The sampling pipe is fitted with a flame arrester and a filter (ensure these are not

chocked during usage coz could give wrong readings)

setting up

- FOR ZERO SETTING: use atm air - FOR SPAN SETTING: use pentane gas

Working

- The battery for the device is checked and switched on

- All the resistances equally get heated up resulting in balanced bridge (i.e. no current flows through the circuit)

- Ensure - The device is properly purged - Then, its taken to the area to be measured - The gas is sucked in via aspirator - One filament in way of the aspirator is a heated filament

(remember – this measures only in the range of LFL (i.e.)0 to 100% of LFL) - The hydrocarbon gasses burn due to the heated filament and increases the temp in the

resistance - Increase in temp changes the resistance (i.e increases the resistance here)

- Because of change in resistance , an unbalance is occurred which leads to current flow

in the circut - The amount of current is measured and the value of HC gas is calibrated accordingly

Note: This can only measure in terms of LFL, if the atm is in HFL , this can be vividly seen by a jump of the reading from max to min as when the sample is sucked Used – in pump rooms etc WRONG READINGS – REASONS

- Filter chocked - Flame arrestor chocked - Not properly purged - Hole in sampling tube - Measuring cell cracked - Battery low voltage

DISADVANTAGE

- Cannot be used to measure HC content in Inert gas TANKSCOPE

- This is also a wheat stone bridge with R balanced - Platinum filaments are used - The difference between tankscope and explosimeter is that here - When sample is passed, the Hydro carbon absorbs the temp of platinum Resistor and

gives a value - No explosion takes place

DISADVANTAGES

- Less sensitivity

PUMPS SUBMERSIBLE CARGO PUMPS (Mc George aux pg 200) Oil pr input 170 bar Outlet pr – 3 bar Material : stainless steel pipes and casings to withstand corrosive effects of most chemicals Consists of 3 concentric pipes

- Inner two for 1. Inlet of Hydraulic oil (170 bar) – speed of this oil is controlled via a speed control valve 2. Outlet of Hydraulic oil ( 3 bar )

- Outer most pipe – Coffer dam ( used for purging ) - Via this valve , the air (preferably N2 )is purged and it acts a tell tale hole revealing if

cargo side gland or hydraulic oil gland has a leakage About this pump

- Every tank has individual pump Stripping operations

- Speed control valve is closed – becoz u r driving it with stripping pump - IG is provided after Deck discharge valve closed

Thus stripping is done

SEWAGE TREATMENT PLANT SEWAGE TREATMENT PLANT (Ref Mc George aux 110 )

- The exact amount of sewage and waste water flow generated onboard is difficult to

quantify - The European designers concluded to 70 ltrs/day and 140 lts/day – including bathing

water - The US authorities concluded 114 lts/day and 228 lts /day including bathing water

Aerobic bacteria

- These are bacteria’s that require oxygen to thrive - These feed on the stools and convert it to water and sludge - They produce Co2 as remains

Anaerobic Bacteria

- When oxygen content in the effluent is less - These bacteria s are formed - While they are equally capable of breaking down sludge., - The problem with these bacterias are while breaking down they produce H2S gas and

methane , and CO (which is very toxic and is flammable) Working of STP

- The stools with water first is discharged in a primary compartment whr the stools are

grinded - This then passes to the aeration chamber ( its continuously bubbled via a blower) - The aerobic bacteria is supported which turns the stools to water and sludge - Now, the sludge will settle down in the hopper tank , if its not pumped back, anaerobic

bacteria would be formed giving foul odours - its pumped back to the aeration tk - (over a period of time the aeration tk would be filled with sludge. – this is desludged at

intervals of about three months) - the desludging operation: pumping 75% of tank and refilling it with clean water

- The clear effluent discharged from settling tank must be disinfected to reduce the number of coliforms to an acceptable level

- Its then treated with Calcium or sodium hypochlorite The treated effluent is held in the tank for 60 mins And then pumped OVBD as per reg Some plants also have UV radiation ! BOD – BIO CHEMICAL OXYGEN DEMAND

- It’s the amount of oxygen required for the aerobic bacteria to break down organic material in waste water

- This determines the efficiency of the plant and strength of sewage - Lesser the BOD better is efficiency is

Raw sewage: 350 to 360 mg/ltr Tested:

- A sample is taken – 20 ml , and dissolved oxygen content is measured - and incubated in dark for 5 days - After 5 days, the dissolved oxygen content is measured - The difference in the oxygen content measure s the efficiency of the plant

Working for my understanding

- The sample contained some aerobic bacteria and some organic matter ! - Since this was taken in the chlorination compartment - The sample should have aerobic bacteria but not organic matter - So lesser the organic matter – better is the efficiency - Hence a sample is taken and oxygen content is measured - When its incubated for 5 days the remaining organic matter (if any) would be broken

down by the e coli bacteria - When it does it !., it consumes oxygen – hence proportionate to the amount of oxygen

consumed , the same amount does organic matter exists

- Hence LESSER THE OXYGEN CONSUMPTION , would mean, there were only less organic matters ! –

- Hence better the efficiency

(refer Marpol floder -> sewage annex 3 latest amdments.pdf)

IMO BEFORE IMO PRESENT

BOD (mg/ltr) TSS (mg/ltr) Residual chlorine content (mg/ltr) Coli form

Not more than 50 100

- 2% max

-

Not more than 25 35 Less than 0.5 125

INCINERATOR MY SHIP SPECS CAPACITY: 3,00,000 Kcal/Hr Waste oil: 37 kg/hr (with 20% of water) Solids: 25 Kg/hr Solid Hole lxb = 400 x 350 mm Burner Type: Rotary cup type Capacity: 37 kg/hr Motor: 0.4 KW 4 pole – 1 ampere Class F insulation

FRESH WATER GENERATOR SPECS CAPACITY 30 T/ Day MAX salinity 2 ppm Cooling sea water 35’c / 70,000 kg/hr Jacket cooling water 85’c/ 50,000 kg/hr