Is it necessary to choose a variable frequency motor for an 8~300L/h metering pump?
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Hello everyone, our company is making a dosing device with a minimum delivery flow of 8L/h and a maximum of 300L/h. It uses a 0~100% adjustable hydraulic diaphragm metering pump. It was originally equipped with a 0.55kw ordinary motor. Now the customer requires a variable frequency motor. I would like to ask if this is necessary. Well, it is necessary to choose a variable frequency motor for a general dosing device equipped with a centrifugal pump. The frequency of the motor is changed according to the real-time flow rate or pressure of the main pipe to achieve the purpose of changing the amount of dosing. But now with such a small motor and the pump flow rate is adjustable, why should we choose a variable frequency motor? Have you seen any examples of this? If you do not choose a variable frequency motor, is there any basis to convince customers?
You can communicate with the customer. It stands to reason that the flow rate changes too much and you need to consider adding an inverter. However, the flow rate of your pump is too small and the motor power is very low. The cost of adding an inverter is not proportional to the cost of saving energy. You can calculate the account for the customer. If the customer strongly requests it, you still have to respect the customer's opinion. After all, they are Party A!
2# I am wrong. 8~300 is not a changing flow rate, but the flow rate of all pumps. The smallest pump is 8.3, and the largest one is 300. Sorry.
The hydraulic diaphragm metering pump itself is a general mechanical equipment that can quantitatively transport various liquids with stepless adjustment in the range of 0 to 100% according to the requirements of the process flow, and the metering accuracy of the transported medium at the maximum stroke is ±1%. When the user proposes to use a variable frequency motor, it may be because he does not understand the performance of the hydraulic diaphragm metering pump. He must respect the customer, but he is also responsible for the customer.
The 8L metering pump seems to have no flow rate and needs an inverter. Well, for 300L, it is quite common to add an inverter. The metering pump adopts a two-dimensional adjustment method, with handwheel adjustment and frequency conversion control. Generally speaking, manual adjustment is coarse adjustment, and frequency adjustment is fine adjustment. After all, in this mechanical thing, the more mechanical pairs there are, the greater the error. When the customer requested frequency conversion adjustment, did they consider the aspects of automatic control and signal reception? If you adjust it once a day, it doesn't matter if you adjust it manually. If you adjust it 8 times an hour, then manual adjustment is a little bit. . . I think it will be difficult to convince customers not to use frequency conversion in terms of price. Let's convince him based on whether he needs automatic control, the time period for adjustment, or what they adjust the flow based on. However, some customers may think that you don’t have an inverter and that the PLC is not of high quality. A customer once asked me to quote this way. . . P.S.: Metering pump, manufacturer. Rizhao Dahua Fluid Control Co., Ltd. Shanghai Office www.rzdh.com 021-54992250
You can't convince a state-owned enterprise because it has money. Private enterprises do not need persuasion, they will settle the accounts.