The relationship between flow rate and pressure

I would also like to ask, what is a Type III electrical transmitter? What’s the difference from ordinary transmitters?

One more question: For differential pressure transmitters, if the positive pressure side is blocked, it shows the minimum value, and if the negative pressure side is blocked, it shows the maximum value, right? Will the displayed value be outside the range? What about differential pressure flow meters?

The pressure sensor is located at the front; generally, it is not necessary to insert it into the pipeline, which does not affect the stability of the flow rate. Furthermore, flow rate is independent of pressure and depends on the pressure difference; the greater the pressure difference between the front and back, the faster the flow rate, and thus the higher the flow rate

So, is it related to the outlet pressure of the pump? Not enough characters, ugh

It doesn’t matter which one is installed first; it’s best if there are no other changes in the straight section of the flow meter. Within the same pipeline, it’s hard to determine the relationship between pressure and flow rate. For example, if a pipe has an outlet valve and it is closed tightly, the flow rate will be very low while the pressure might be high. However, with the same pipe diameter and no changes at the outlet, the higher the pressure, the faster the flow rate. An electrical Type III transmitter refers to a signal of 4~20mA DC. In contrast, Type II electricity is a 0–10mA DC signal. “For differential pressure transmitters, if the positive pressure side is blocked, it shows the minimum value, and if the negative pressure side is blocked, it shows the maximum value, right? Will the displayed value be outside the range? ”Could you explain in detail the situation you encountered? In a differential pressure flow meter, if the high-pressure side is blocked, the reading will be negative; if the low-pressure side is blocked, the reading will be high and may exceed the range.

When displaying the mass flow rate, it is necessary to know the differential pressure, absolute pressure, and temperature; these values can be used to calculate the mass flow rate. It cannot be said that pressure measurements are useless – it’s just that some orifice plate flow meters come equipped with multi-functional transmitters that capture the absolute pressure along with the differential pressure. Brands such as Rosemount, Yokogawa, and ABB offer such multi-functional transmitters, which only require a temperature signal to determine the flow rate. However, some manufacturers, like E+h, do not use multi-functional transmitters; instead, they measure the absolute pressure, the differential pressure using an orifice plate, and then the temperature. Only after processing these three signals in a flow computer can the flow rate be determined. In this case, manufacturers recommend installing the absolute pressure transmitter first along the pipeline, followed by the orifice plate differential pressure transmitter, and finally the temperature transmitter.

I’ve learned it, thank you! Why in the question bank of our company is there a question that provides the current value and range in order to calculate the pressure value of a Type III electrical pressure transmitter, and why does the answer require squaring the current value?

Do you need to know the temperature to calculate flow rate? I really hadn’t noticed; I’ll learn it now, thanks!

If the pump’s output pressure is 10 kilograms and material needs to be fed into a reactor with a pressure of 11 kilograms, can it be pumped there? Definitely not, because the pressure difference is insufficient, so there is no flow. The greater the pressure difference, the greater the flow rate

Oh, I see. So in other words, the flow rate actually depends on the difference between the pump’s outlet pressure and the main pipe pressure, right? Thank you for the advice