what is the function of shuttle valve in that cabinet and pressure switch.
during manula mode of operation can we operate extended discharge first and initial discharge later.

 

Can you be more precise about which cabinet you are talking about, CO2 cabinet or turbine compartment?

shuttle valve in the turbine comp is to close compartments in case of fire to avoid any fresh air (and mostly oxygen) to enter to kill more rapidly the fire, normally F&g panel and MARK 5 or 6 should also stops all fans which can introduce fresh air in the compartments.

Shuttle valve in the CO2 container? I need more info about this one I don't know.

Pressure switch (I suppose on the Co2 line) this is to tell F&G panel that the CO2 is discharging it will give some actions in the system itself (see your cause and effect diagram) and mostly will tell operator that bottles are empty.

NO you cannot discharge independently initial and extended lines and surely not the extended before the initial. on a "normal system" both initial (also called fast discharge) and extended (called Slow discharge) discharges trigger at the same time.

The principle being that the fast discharge is used to introduce as fast as possible the maximum of CO2 (a minimum of 30% within 30 seconds is a normal operating way) in the compartment to "kill" The fire, the slow discharge is to maintain this 30% CO2 for at least 30 Minutes after the initial discharge to be sure the fire is completely dead.

This is why it is not advisable to enter any compartment where CO2 discharge has occur at least before two hours and ONLY AFTER VENTING (once you are sure the fire is out)

 

Hi there,

We use a different system but the workings of a shuttle valve is such that it allows a outlet from two different inlets, but as long as there is more pressure on the one inlet the second inlet is blocked (normally balls and springs on the inlets).

So I suspect that it is used on the main CO2 line to the turbine from the initial and the reserve banks.
You should also have some solenoids to actually electrically do the activation of whatever bank is selected (if your system have this feature). If it is activating the initial bank first then the shuttle valve will block the inlet from the reserve bank.

It might also be possible that your system will activate both banks simultaneously (or the second bank only after a time delay) and the shuttle valve is then there to start the release of the initial bank first and as the initial bank's pressure drops the shuttle will start to move over (due to the still high pressure in the reserve bank)and begin releasing the reserve bank as well. If it does work like this and both banks are identical it will not matter which one you release first, the effect will be the same.

Our system is very complex in that it needs to see a confirmed release on the initial bank within 5 seconds otherwise it will release the reserve bank automatically. We also use electronic scales to measure the weight of the bottles with a alarm when the weight goes below a certain weight indicating the bottles are empty.

The pressure switch in our system is used to indicate the "confirmed release" to the CCR which will have the effect of closing the dampers, CO2 local alarm and lights and stopping the fans.