Hi,
Recently in my plant, we have been experiencing irregular flow meter readings when charging in a particular chemical. My production is in batches, so at every batch, we would charge in a fixed amount of chemical into the reactor by calculating the flow rate of the chemical through a pipe.
Normally, we'd see the readings increase at a steady rate i.e. 1 kg every 3 seconds until the set point is reached. The pump and valve closes at Set value of 75 kg, and the calculated weight charged in would be 75 kg. However recently, i have noticed that there is a slight spike in weight at the end of the chemical charging once the pump and valve closes. Sometimes the calculated weight would jump 1 - 2 kg additionally upon closure of valve.
My flowmeter configuration is the flowmeter, with 2 isolation valves directly before and after this meter. Recently the isolation valve just downstream of the flowmeter has been throttled to address an issue, and it seems like the flowmeter reading trouble only started with the throttling of the isolation valve.
Long story short, i just wanted to know if throttling of a valve just downstream of a flowmeter could affect the accuracy of the readings? Especially during pump stop / outlet valve closure period.