Discussion on flow measurement using differential pressure transmitters
Thread Content
What are the hazards and consequences of the balance valve in the three-valve assembly not being fully closed when using EJA Yokogawa or Rosemount differential pressure transmitters to measure flow rate?
Without an effective separation between the positive pressure side and the negative pressure side, the pressure difference becomes smaller. So, what impacts will this have? Traffic is low. (According to the principle of differential pressure flow meters)
As the differential pressure decreases, the flow rate naturally decreases as well
If the balance valve of the three-valve assembly is not fully closed, the pressure difference between the positive and negative diaphragm chambers will decrease, resulting in a measured flow rate that is lower than the actual flow rate.
It affects the static characteristics; changes in pressure difference can be observed temporarily, but over time the pressure difference between the two sides decreases or even disappears
Result: The readings of DCS/SIS are low (the actual flow rate is high). Consequences: 1. In the FI circuit, the measured flow rate is lower than the actual flow rate, which misleads the process. 2. In the FIC circuit, the low measurement values cause the control valve to open automatically until it is fully open. 3. FSLL interlocking, resulting in incorrect train stoppage ； FSHH interlock, resulting in no shutdown. @jiaguoyun @Big Horse with Big Bow