ICGSMA Bulletin - Indian Coast Guard
ICGSMA Bulletin - Indian Coast Guard ICGSMA Bulletin - Indian Coast Guard
ICGSMA BULLETIN (JAN - MAR 13) existing sea water pump fitted on Main DA is gear driven and has a capacity of 90 LPM. The existing fitted pump has a rubber impeller to boost sea water pressure. However the sea water pump fitted on Harbour DA is a gear driven pump with a capacity of 125 LPM and has metallic impeller to generate the pressure on sea water. The gear profiles of main and a harbour DA sea water pump is identical. The sea chest suction point for main DA’s are located offset towards starboard side from the centre line of the ship and has a suction head of approximately 10 mtrs & 06 mtrs for port & stbd DA respectively. The sea chest suction for Harbour DA is located offset towards port side from the centre line of the ship and has a suction head of approximately 05 mtrs. MAIN DA SEA WATER PUMP discharge side of the pump and extent of the damage to the rubber impeller propagates, as the cooling water does not reach up to rubber impeller of the pump. Emergency cooling on these DA’s is only possible after removing of entire pump assembly along with the drive gear and blanking of gear drive port hole with corresponding oval shaped flange whereas the sea water pump fitted on Harbor DA can withstand the oscillations of the ship well above the normal range and even during sea state 3-4. The emergency cooling on this DA is also possible in case of failure of sea water pump without removal of the pump and causing damage to the pump impeller and other parts view this pump is provided with metallic impeller and also Shaft Casing Impeller Drive Gear REPORT ON REPEATED DEFECT ON MAIN DA SW PUMP It has been observed that, During sea state 3-4 when the ship is rolling, the sea water pumps of Main DA are not taking suction and fresh water temp of these DA’s abruptly shoots up due to non availability of cooling water and subsequently leading to tripping of main DA’s while at sea. Running of these DA’s with emergency cooling is also not possible as this line is connected to the have higher capacity than the sea water pumps fitted on main DA’s. Many a times the ship’s staff has faced difficulties to run main DA’s at sea state 3 and higher due to failure of their sea water pumps. In such situation option available is to shift the ships load on Harbour DA with limitation on load due to less capacity compared to Main DA. The ship’s staff has confirmed this phenomenon in all the ship of FPV class. An insight to trouble shooters 14
ICGSMA BULLETIN (JAN - MAR 13) SUGGESTION The ship has projected this difficulty to the PAC firm M/s Powerica and also suggested for feasibility of fitment of Harbour DA sea water pump on main DA as the gear profile for both the DA sea water pumps is identical. The reps of PAC firm has confirmed the fitment of Harbour DA sea water pump on main DA’s with minor modification on routing of the suction & discharge lines of the pump. Recommendation of this modification is requested to be assessed with expertise and may be implemented in all the ship of this class. BELLOW TYPE THERMOSTAT It has thin brass bellows fitted to the frame at the bottom and to a valve at the top. It is filled with Ether, Alcohol or Acetone. This liquid vaporizes at their respective boiling point. THERMOSTAT INTRODUCTION JK Selvan, U/Nvk (ME) ICGS Rajkamal The functions of the thermostat are as follows:- (a) Thermostat is a device which prevents the engine from getting overcooled when running under normal condition. (b) When the engine is started from cold, it remains closed so that pump circulates coolant(water) through cylinder jacket only. (c) When engine reaches optimum operating temperature the thermostat starts functioning. (d) When the coolant water reaches above the operating temperature thermostat opens allowing hot water to flow through the cooler and get cooled. TYPES OF THERMOSTATS The different types of thermostats are:- (a) Bellow type thermostat (b) Wax element type thermostat At lower temperature the poppet valve remains seated as bellows remain contracted. Water is prevented from flowing through the cooler. As the water gets hotter, the liquid evaporates and the vapour exerts pressure inside the bellows the valve gets open. A giggle pin allows flow of air from bellows while charging it with ether or alcohol. WAX ELEMENT TYPE TERMHOSTAT The wax is surrounded by a rubber sleeve. A movable thrust pin has its conical end dipped in the wax and its upper end screwed in the body. The valve is fitted to the upper end of the container which is surrounded by hot water. As the temperature of the water rises, the wax melts and forces the pin out of the wax container. The valve alongwith the container moves down against spring pressure. The spring pushes the container back to its original position as the wax cools down. An insight to trouble shooters 15
- Page 1 and 2: QUARTERLY MARCH 2013 VOL -3 ISSUE-1
- Page 3 and 4: ICGSMA BULLETIN (JAN - MAR 13) Cont
- Page 5 and 6: ICGSMA BULLETIN (JAN - MAR 13) (PCT
- Page 7 and 8: ICGSMA BULLETIN (JAN - MAR 13) A su
- Page 9 and 10: ICGSMA BULLETIN (JAN - MAR 13) ANAL
- Page 11 and 12: ICGSMA BULLETIN (JAN - MAR 13) BEFO
- Page 13 and 14: ICGSMA BULLETIN (JAN - MAR 13) like
- Page 15: ICGSMA BULLETIN (JAN - MAR 13) * Us
- Page 19 and 20: ICGSMA BULLETIN (JAN - MAR 13) KNOW
- Page 21 and 22: ICGSMA BULLETIN (JAN - MAR 13) An i
- Page 23 and 24: ICGSMA BULLETIN (JAN - MAR 13) An i
- Page 25: ICGSMA BULLETIN (JAN - MAR 13) Dear
<strong>ICGSMA</strong> BULLETIN (JAN - MAR 13)<br />
existing sea water pump fitted on Main DA is gear<br />
driven and has a capacity of 90 LPM. The existing<br />
fitted pump has a rubber impeller to boost sea<br />
water pressure. However the sea water pump<br />
fitted on Harbour DA is a gear driven pump with a<br />
capacity of 125 LPM and has metallic impeller to<br />
generate the pressure on sea water. The gear<br />
profiles of main and a harbour DA sea water pump<br />
is identical. The sea chest suction point for main<br />
DA’s are located offset towards starboard side<br />
from the centre line of the ship and has a suction<br />
head of approximately 10 mtrs & 06 mtrs for port<br />
& stbd DA respectively. The sea chest suction for<br />
Harbour DA is located offset towards port side<br />
from the centre line of the ship and has a suction<br />
head of approximately 05 mtrs.<br />
MAIN DA SEA WATER PUMP<br />
discharge side of the pump and extent of the<br />
damage to the rubber impeller propagates, as the<br />
cooling water does not reach up to rubber impeller<br />
of the pump.<br />
Emergency cooling on these DA’s is only<br />
possible after removing of entire pump assembly<br />
along with the drive gear and blanking of gear drive<br />
port hole with corresponding oval shaped flange<br />
whereas the sea water pump fitted on Harbor DA<br />
can withstand the oscillations of the ship well<br />
above the normal range and even during sea state<br />
3-4. The emergency cooling on this DA is also<br />
possible in case of failure of sea water pump<br />
without removal of the pump and causing damage<br />
to the pump impeller and other parts view this<br />
pump is provided with metallic impeller and also<br />
Shaft<br />
Casing<br />
Impeller<br />
Drive Gear<br />
REPORT ON REPEATED DEFECT ON MAIN DA SW<br />
PUMP<br />
It has been observed that, During sea state<br />
3-4 when the ship is rolling, the sea water pumps<br />
of Main DA are not taking suction and fresh water<br />
temp of these DA’s abruptly shoots up due to non<br />
availability of cooling water and subsequently<br />
leading to tripping of main DA’s while at sea.<br />
Running of these DA’s with emergency cooling is<br />
also not possible as this line is connected to the<br />
have higher capacity than the sea water pumps<br />
fitted on main DA’s.<br />
Many a times the ship’s staff has faced<br />
difficulties to run main DA’s at sea state 3 and<br />
higher due to failure of their sea water pumps. In<br />
such situation option available is to shift the ships<br />
load on Harbour DA with limitation on load due to<br />
less capacity compared to Main DA. The ship’s staff<br />
has confirmed this phenomenon in all the ship of<br />
FPV class.<br />
An insight to trouble shooters 14
Change language