After starting the pump, the outlet valve is very small, but the current is high – why?
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Every time the fire pump is started, the current reaches almost its rated value as soon as the outlet valve is opened to around 5. The pipes are empty yet the current remains so high; it’s hard to understand. Isn’t it true that the larger the outlet, the greater the power and the higher the current?
Close the outlet valve, start the pump, then slowly open the valve
Maybe the motor is too small, so it only runs at 5.
There could be several reasons for the situation you described. One is a design issue: if the diameter of the outlet pipe of your fire pump is too large, and the flow rate through the pipe at the rated pressure exceeds the pump’s rated flow rate by too much, it may prevent the outlet valve of the fire pump from opening fully. Another possibility is that the motor designed for the pump is not suitable – its power is insufficient to meet the pump’s flow requirements； Secondly, there may be a problem with the pump or motor itself; if the rotating parts of the pump or motor are stuck or out of alignment, it could cause the motor to operate under excessive flow conditions ； Third, there is a problem with the valve; the indicated opening degree does not match the actual opening degree, leading to incorrect readings ； Fourth, there is a problem with the operation; if the outlet valve can be fully opened after the fire pump is running normally, and the issue you mentioned occurs only when starting the pump, then it indicates that the above three factors can be ruled out. In that case, it is sufficient to open the outlet valve slowly each time the pump is started.
You think it’s very likely that the traffic has already exceeded the limit! No flow meter, no outlet pressure gauge! How do you judge?
Close the outlet valve, start the pump, then slowly open the valve
Is a butterfly valve used at the outlet of the fire pump? If it is a butterfly valve, this is possible; with it set at 5% open, and since there is no backpressure downstream, it is normal for the flow rate to be high. At this point, the valve should be opened gradually; once the pipeline is filled with water, it can then be opened fully.
The outlet valve should be closed; start the pump, and then open the valve after the pump has started
Yeah, it’s this process; it’s just that if the outlet valve is opened too wide, it will trip