The working principle for this station is the same for the fire protection jokey and Electric pumps which are connected in parallel if there's small pressure drop in the system due to leakage the pressure will be drop until it reaches the setting point of jokey pump so it will comes to service If the pressure dropped more due to sprinklers operation or hose cabinet the pressure will be reduced more until reaching the setting point of the electric pump it will come also to service to fulfill the demand of higher flow and so on. So by this configuration we keeping the larger PRV from continuous operation to protect it from cavitation for long life operation. Also this station may be working alternatively during maintenance works in one side branch keeping the other working delivering water to the system.
It means that at a time both PRVs work in auto mode and the pressure will maintain as per setting but flow varies as per demand. Kindly confirm, if may I wrong.
To me it is because large valves work well with large flows..but when flows become smaller (for instance at night) you need a smaller PRV to do correctly the job. If i remember well the way to choose the correct diameter of the PRV is directly linked with the flow and of course the PN.
Considering the downstream side if the demand for flow is small or decreased the pressure will increase till reaching the pressure setting of small prv which will be enough to fulfill the demand which is limited to 65 psi But if the demand becomes higher the downstream pressure will be dropped to the sitting point of the larger prv which is limited to 60 psi So it will be introduced to the service also Until the demand becomes lower again the downstream stream pressure will rise again and the larger prv will be out of service and the small prv is only in service
The working principle for this station is the same for the fire protection jokey and Electric pumps which are connected in parallel if there's small pressure drop in the system due to leakage the pressure will be drop until it reaches the setting point of jokey pump so it will comes to service
If the pressure dropped more due to sprinklers operation or hose cabinet the pressure will be reduced more until reaching the setting point of the electric pump it will come also to service to fulfill the demand of higher flow and so on.
So by this configuration we keeping the larger PRV from continuous operation to protect it from cavitation for long life operation.
Also this station may be working alternatively during maintenance works in one side branch keeping the other working delivering water to the system.
It means that at a time both PRVs work in auto mode and the pressure will maintain as per setting but flow varies as per demand. Kindly confirm, if may I wrong.
Its to protect larger from cavitation etc
To me it is because large valves work well with large flows..but when flows become smaller (for instance at night) you need a smaller PRV to do correctly the job. If i remember well the way to choose the correct diameter of the PRV is directly linked with the flow and of course the PN.
Considering the downstream side if the demand for flow is small or decreased the pressure will increase till reaching the pressure setting of small prv which will be enough to fulfill the demand which is limited to 65 psi
But if the demand becomes higher the downstream pressure will be dropped to the sitting point of the larger prv which is limited to 60 psi
So it will be introduced to the service also
Until the demand becomes lower again the downstream stream pressure will rise again and the larger prv will be out of service and the small prv is only in service