2 replies to this topic

[RKottam]

Hi All,

Hi,
I want to design vaccum breakers/Air releave valves at high elevation points of the offshore platform fire water system. I would like to know is there any guide lines to design these breakers to avoid column seperation. I am looking for the following details.
1.how many number of breakers are required?
2. how can we design the location of the one breaker to the other
3. What are the critical parameters to be taken into account to design these breakers.
I really appreciate your reply.

Thanks

Regards,
RK

[Art Montemayor]

I moved this thread from the Simulation Forum since it obviously was there in error.  This is a vacuum or pressure RELIEF topic that belongs here.

 

Additionally, please define what you mean by "breakers" and "air release valves" and where they are located within your system.  A P&ID or detailed flow diagram should be submitted to aid in fully understanding your query.

[RKottam]

Hi, Thank you for your reply.

I will try to explain my question little bit more detail.

 

In fire water system of the offshore platform, during fire and gas release scenario, deluge valve receives a signal to open, and opens because it is actuated by instrument air or some other means. At the same time, the fire pump

receives a signal to start. However, it takes time for the fire pump to prime the caisson and,

during that time, it is not possible to maintain the pressure in the ringmain. Hence, vacuum

pressures would develop in the higher parts of the system, which could lead to cavity formation.

 

 

Installing vacuum breaker valves or air release valves at the high points in

the system is one way of controlling pressure surges that arise from cavity separation.

Working principle of the vaccum breaers is,  before the fire pump has primed, it allows air to enter the system quickly, so that the pressure at the higher levels of the ringmain remain close to atmospheric pressure. When the

pump has primed the system, the air release valve (which is a much smaller valve), allows the

air to exit relatively slowly.

 

 

 

Now my question is, how to design these vaccum breakers/air release valves.

How many of them are required, what should be their size, what is the location of the one breaker to the other etc.

 

Thank you.