Understand volume inputs to the Pipeline Monitor (PLM) region

Before volumetric change in the Pipeline Monitor (PLM) region can be calculated, each input device to the region needs to be read and the volume change calculated. The change in value for a meter, linepack segment, or tank is determined as the difference between the current value and the value when the variance was last calculated. The minute-to-minute changes for the previous 30 minutes for each device are saved in the plmvoldevice record that references the device.

Although the basic calculation for each device type is similar, there are variations between device types; therefore, they need to be discussed separately.