Hello,

I need to provide CO2 fire suppression system with 34% concentration for turbine enclosure. Further, I need to provide both initial discharge and extended discharge for 30 min and concentration for both discharge will be 34%. Kindly clarify whether the qty of Co2 and no of co2 cylinders will be same for both initial discharge and extended discharge or different.

 

Dude,

You need to know the volume of the enclosure(s), the nozzle area and the pressure of the CO2 bottles--there are low-pressure C)2 systems and high-pressure CO2 systems.

Usually, in my experience, the number of cylinders (the high-pressure cylinders) for the initial discharge (to flood the compartment(s) with CO2 as quickly as possible) is about half the number of extended discharge CO2 cylinders, as the extended discharge system needs to maintain the concentration of CO2 for the required time (you say 30 minutes) after the initial discharge system is empty. There is also always some leakage through rusted enclosure metal, rusted door frames, non-working gravity-operated dampers, improperly latched CO2 operated dampers (depending on the construction of the machine), etc.

If you're trying to retro-fit an older machine, you should have access to the P&IDs for the Fire Protection System (and ALL the systems) and refer to them for assistance and possibly even recommended nozzle sizes, number of nozzles, etc.

CO2 system tests can be very rigorous. I worked at a site where CO2 was discharged eight times if I recall correctly trying to get the concentration in the turbine compartment to hold for the required time. Finally, I started pulling trench covers (the CO2 piping was in a concrete trench below grade) and another person found a section of the CO2 piping between the CO2 system and the turbine compartment that was frozen solid. That section of pipe was cut out and found to have an occlusion of zinc galvanization which had resulted in a very small passage (in a 1-inch pipe (nominal size) which was, effectively, a nozzle, and that caused a pressure drop and a temperature drop and the CO2 in the pipe froze solid at the occluded section. The CO2 concentration would build up to required and after about 10 minutes we noted there was no more flow out of the storage tank (a low-pressure system) and the concentration degraded pretty quickly. The CO2 storage tank had enough CO2 for 2-1/2 discharges, and we had to keep getting a tanker truck out to fill it up again. And the Fire Marshall made is test EVERY compartment EVERY time one compartment failed. (It was a union job in a very heavily unionized area, and a LOT of people, who had to leave the building every time the CO2 was discharge (the turbine was inside a larger building) got paid for sittin' on their arses and whinging about not having anything to do (but they took the money, because there was BIG overtime involved in getting the CO2 concentration test done, and they didn't have to do anything but be on site so when the test was deemed successful they could immediately return to their previously assigned tasks). There was ALL KINDS of fancy air- and CO2 monitoring equipment, and the leakage rate had to be less than a certain amount before the test could even start--and that took a few days to seal all the leaks to the Fire Marshall's satisfaction (but at least the workers could keep working on their normal tasks; large high-volume fans blew air into the enclosure and the pressure and flow was closely monitored to determine enclosure leakage).

Some sites only require what's called a "puff test." Large plastic bags are tied around each discharge nozzle, and a small amount of CO2 is discharged through each set of nozzles and the bags are checked to see if they burst (from the pressure of the CO2). And if all the bags were found ruptured, the CO2 system is declared operational. It all depends on the insurance company's and/or the appropriate fire agency's requirements--whichever requirements are more stringent dictates how the test is to be done and what the requirements for passing are.

But, we can't help you with your calculations. You haven't even touched the surface of the data (actionable data) that would be required for anyone to provide any assistance. And, again, you may--or may not--have to satisfy either an insurance company's requirements and/or a local fire agency's requirements (some very large industrial plants and refineries have their own fire department that sets requirements for the equipment).

Find the original P&IDs and use them as your starting point. Find out (if you don't already know for certain) what the requirements are and plan accordingly. Plan your work, and work your plan is the best way to get any task like this done. Understanding requirements is key and part of the planning. "A failure to plan is a plan to fail," is another very true statement.

And trying to do these kinds of tasks without providing any information (actionable data) is, well, not going to achieve the results you want. And, to be honest, without providing a LOT of information and data there's not a lot anyone can do to help you.

Best of luck!