co2 fixed fire fighting system for engine room

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sivagurunathan
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co2 fixed fire fighting system for engine room

Postby sivagurunathan » Thu Jan 23, 2014 8:45 pm

in the fixed co2 fire fighting system the pipeline sections need to pressure tested periodically for 190 bar till the main discharge valve; 80 bar after discharge valve till entry into engine room; 6 bar at lines inside engineroom. these pressure test is usually done at drydocks. my doubt is what is the medium used to do pressure test is it water or any other medium (for 190 and 80 bar). and which is the point of injection ....is there any dedicated point given to do pre testing of 190 and 80 bar or is it done by disconnecting safety valve given in the manifold and using that opening as point of injection. while doing 190 bar pressure testing the co2 bottles are connected to manifold or it should be disconnected? kindly share the experience....
Last edited by sivagurunathan on Fri Jan 24, 2014 4:37 am, edited 1 time in total.

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JK
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Re: co2 fixed fire fighting system for engine room

Postby JK » Fri Jan 24, 2014 4:20 am

I don't know if you are planning on doing this, but you yourself or the shipyard does not do this work.
For Regulatory/Class you must have a recognized fire system contractor such as Don Bretons to do the testing and give a certificate that will meet regulations.

sivagurunathan
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Re: co2 fixed fire fighting system for engine room

Postby sivagurunathan » Fri Jan 24, 2014 4:39 am

sir this question was asked during my oral examination. since i have not been to drydock iam looking for a practical answer.

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Big Pete
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Re: co2 fixed fire fighting system for engine room

Postby Big Pete » Fri Jan 24, 2014 7:01 am

YOU NEVER, EVER, CARRY OUT A PRESSURE TEST USING AIR OR ANY OTHER GAS.
If the system bursts under the pressure Test the gas will expand, accelerating the broken pieces of metal outwards, exactly the same as a bomb, and just as lethal.

Pressure tests are always carried out Hydraulically, this usually means water, because that is cheap, safe and readily available, but if it would cause corrosion or other problems, another INERT liquid could be used, NOT OIL or any other flammable/harmful liquid for obvious reasons! (incidentally, the Royal Navy doesn't use Oil in its Hydraulic systems, but a mixture of Glycerine and water to reduce the fire risk)

I have never seen a pressure test carried out on a CO2 system, in 42 years at Sea. I imagine it would only be done by the installer while the ship was being built. More likely the materials and method of connecting the pipework would be approved and the actual installation visually inspected after completion of the installation, possibly also an Hydraulic test on the high Pressure manifold might be witnessed in the makers workshop before installation. Standard Pipes and Pipe fittings are all rated for pressure, so long as they are correctly assembled there should be no need to pressure test them. The Subsequent surveys are based on a visual examination of the pipework, and only if the Surveyor was unhappy with the visual inspection would he request a pressure test. Welding should be carried by someone qualified to weld the materials for use at the pressures involved. Remember that the Rules for designing, building and testing pressure vessels are different to those for pipes under pressure. (If I remember correctly the difference between a pipe and a pressure vessel is determined by the ratio of length to diameter)

Because the different sections have to be pressure tested to different pressures, the system would have to be dismantled with each section blanked off from the lower and Higher pressures, then tested and finally it would all have to be re-assembled afterwards. There would be no way to pressure test the completed joints between the different pressure zones after re-assembly, so there wouldn't appear to be much point in doing it

International Rules such as SOLAS now requires all work on Safety and Fire Fighting equipment to be carried out by "Competent People" this is normally interpreted as being the Maker's own Service Engineers or some other Specialist Contractor.

Leaks tests can be carried out using air pressure at less than the working pressure of the system, and spraying soapy water on any areas that might leak.

I am sure Jolly Jack or some other Surveyor will add some more detail to this.

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JollyJack
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Re: co2 fixed fire fighting system for engine room

Postby JollyJack » Fri Jan 24, 2014 9:27 am

from Fire Detection and Extinguishing Equipment Regulations (C.R.C., c. 1422) which are here:

http://laws-lois.justice.gc.ca/eng/regu ... html#h-108

SCHEDULE III
FIXED INSTALLATIONS FOR SMOTHERING BY FOAM, GAS, STEAM OR WATER

Smothering Gas

3. (13) On completion of the piping installation and before the gas cylinders are connected, pressure tests using CO2 or another such inert gas shall be carried out as follows:

(a) the piping from the cylinders to the stop valves in the distribution manifold shall be subjected to a pressure test of 6 895 kPa which shall demonstrate that, with no additional gas being introduced, the leakage of the system is such as not to permit a pressure drop of more than 1 000 kPa per minute for a two-minute period;

(b) the discharge pipes from the distribution manifold to the spaces to be served shall be subjected to a pressure test of 4 137 kPa which shall demonstrate that, with no additional gas being introduced, the leakage of the system is such as not to permit a pressure drop of more than 1 000 kPa per minute for a two-minute period and for the purpose of this test, the discharge piping shall be blanked off within the space protected at the first joint ahead of the nozzles; and

(c) in the case of small independent systems serving such spaces as lamp rooms, paint lockers and similar spaces, the installations may be tested by blowing out the piping with compressed air at a pressure of at least 689 kPa.
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JK
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Re: co2 fixed fire fighting system for engine room

Postby JK » Sat Jan 25, 2014 4:09 am

Thanks Big Pete. I fixed my post so not to take away from reality.


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