Are the outlet valves with one in use and one as backup always open?
Thread Content
It is said that the outlet valve should be closed when a centrifugal pump starts up. I would like to ask: for those centrifugal pumps that are ready for use at any time, isn’t the outlet valve supposed to be open? Otherwise, when the backup pump is started, someone still needs to open the valve
The outlet valve of our backup pump must be closed! The inlet valve must be fully open! When starting the pump, keep the outlet valve fully open; this will result in very high current levels, which can lead to overload and pose a safety risk. From the perspective of protecting the equipment, the outlet valve of the backup pump should not be opened! If it’s a small pump, the impact might not be very significant.
The outlet valve of the self-starting pump must be open; otherwise, the interlock for automatic start-up will not function
So how can we ensure automatic startup of interlocking?
The answer is too simple; how did you do it
It contradicts the replies from the previous people
By looking at the pump’s performance curve, one can understand the principle. The outlet valve is closed to start the pump; the flow rate is 0, the current is at its minimum, and the motor will not be overloaded. The same principle applies to self-acting pumps as well; it simply requires a signal to start the pump, without the need for an on-site button. It has nothing to do with the type of outlet valve, and manual operation to open the valve is still possible ； There are also control valves; just add a sequential control system. Criticism and suggestions are welcome.
The outlet valve of the standby pump in our plant is required to be closed, while the inlet valve is required to be fully open.
It depends on what kind of centrifugal pump it is； Things that are quite important, like the oil circulation pump in the aircraft’s fuel station ； Those with relatively low pressure can ； Generally, the outlet of the standby centrifugal pump is kept completely closed
The inlets and outlets of our backup pump are both fully open; the small motor is fine, and motors of 45kw or higher are equipped with soft starters, so there’s no risk of overcurrent!