Please, experts, take a look and tell me if this teaching method in the school is appropriate
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Take water transportation by a centrifugal pump as an example. The master said that in a company, after the pump is started and the outlet valve is opened, it is necessary to set it to a certain pressure. But our training manuals require students to open the outlet valve and adjust it to a certain flow rate. Do everyone think it’s fine as it is, or should schools be more aligned with the realities of businesses? Thank you!
Flow rate is generally visible only in the control room, while pressure is indicated by on-site gauges; control is shifted from flow rate to pressure based on experience.
Pressure gauges are inexpensive and are generally available for export. Flow meters are expensive and not available everywhere.
In a company, there is traffic and pressure; can such pressure be automatically controlled?
Generally, there are many local pressure gauges but few flow meters
Both factors should be taken into consideration. First of all, sufficient pressure is needed to generate enough drive force; in actual production, the manual valve at the pump outlet is usually left fully open, with the outlet control valve used to regulate the flow rate. Therefore, as long as there is sufficient pressure, that’s sufficient – flow rate regulation is the responsibility of the operator on site
The pressure is adjusted using the minimum backflow setting; if the opening degree of the minimum backflow valve is too large, it will result in insufficient pumping capacity. The minimum backflow valve is kept slightly open while the outlet valve is fully open, with the remaining parameters being adjusted by self-regulating valves in the control room
The pressure of a centrifugal pump remains constant as long as the medium does not change. So after starting the pump, it’s sufficient as long as the outlet pressure remains stable; it cannot be adjusted. The flow rate is adjusted by the operator, but still within a certain range. If it is too large, it will indeed reduce the outlet pressure but cause the motor to overload and trip.
The outlet pressure should be controlled in order to adjust the valve. The head of the pump is determined based on the designed pipeline resistance and the height to which the fluid needs to be pumped. If the pressure indicated by the outlet pressure gauge is too high, it means that the valve is open too little, and the pump certainly cannot achieve the designed flow rate. Too low pressure indicates excessive flow, causing the pump motor to operate under overload. The motor is prone to burning out
Adjusting pressure is simple and feasible, but flow rate is difficult to control. Experience comes from the master, while textbooks are purely theoretical. Many things are truly understood through practice.