Steady-state accuracy and regulation ratio of the metering pump

A metering pump has three levels of precision: steady-state precision, which refers to the condition where the pump remains stationary; flow fluctuations within the pump itself; and the average delivery flow rate, which is what is commonly referred to as the flow rate. This is because the instantaneous flow rate of a metering pump varies, which is why this distinction is made. Repeatability accuracy: Set it to one scale, move it away, then bring it back to test the reproducibility of the flow rate. Linear accuracy: Check how linear the flow rate is at 10%, 25%, 50%, 75%, and 100% scales; adjust it up sequentially and then bring it back. 2. Regarding the regulation ratio, the standards do not specify its value; what is the general requirement? 10%~100%; values below 10% can still be adjusted, but the linear accuracy is very poor. 3. Are these two concepts applicable only to metering pumps with adjustable flow rates, or do they apply to all pumps? (There is a requirement in the standards: the accuracy of steady-state flow should be within ±1 of a ratio of at least 10:1.) This applies only to metering pumps with adjustable flow rates. (Well, how can it be called a metering pump if the flow rate isn’t adjustable – !) ）

Thank you for your reply. I still have questions: 1. Is a flow control device for the metering pump required? Are there clear regulations for API675? 2. Does that mean that without a flow regulation function, steady-state accuracy and regulation ratio are not required?