Commissioning a flow transmitter is a critical step within the package commissioning process, as accurately measuring process flow is essential. Differential pressure type flow transmitters are commonly utilized for this purpose. These instruments help ensure that the process is operating within specified parameters. In this post, we delve into potential errors and corresponding solutions based on past experiences:
- Impulse Lines: The impulse lines, connecting the orifice flanges to the flow transmitter, may face issues like cracks, bends, or blockages from solids. In such cases, it’s crucial to either clean or replace these impulse lines to maintain accurate readings.
- Valve Manifold: Proper configuration of process isolation and equalization valves in the manifold is vital. Ensuring the process isolation valves are open and the equalization valves are fully closed prevents process air leaks, enabling the transmitter to correctly read differential pressure.
- Orifice Plate: Incorrect installation of the orifice plate can lead to deviations in pressure drop. The ‘Upstream’ marking must align with the actual upstream side during installation. If process parameters like specific gravity, density, or viscosity are inaccurately considered during orifice plate design, the pressure drop indication can be inaccurate. In such cases, redesigning the orifice plate according to accurate process parameters is necessary.
- Flow Transmitter: Incorrect installation of the flow transmitter, especially connecting the high-pressure side to the downstream, can cause errors. Also, selecting a transmitter range lower than the actual flow can lead to “Analog Sat” errors during commissioning, particularly if the orifice design is flawed. Recalibrating the transmitter for a higher range on-site or replacing it with a suitable model becomes necessary in these instances.
It’s worth noting that replacing the orifice plate and flow transmitter can result in significant downtime during commissioning. Therefore, proper selection of the flow unit and meticulous validation of orifice datasheets are essential to prevent such issues. For more insights, you can refer to our previous post on flow units. This comprehensive approach ensures accurate measurements and a smooth commissioning process.