Determine the usability of device volumes

The volume indicated by the device record cannot be used if any of the following conditions are true:

• The device is inhibited by the Administrator (inhibit flag in the plmvoldevice record is true).

• The amount of time since the device last had a valid accumulator update exceeds the Stale Timeout value configured for the Pipeline Monitor (PLM) record and the device is either:

  • Not in the second poll state.

  • Flagged as stale and not in manual override.

• The plmvoldevice record is not in the second poll state. This normally happens immediately after the record has returned from an inhibited or suspended condition.

• The PLM record is not calculating (not in second poll state) on the previous processing.

• The plmvoldevice record is associated with a tank source (tank or analog) that has been determined to be in an instrument fail condition.

In the case of a linefill type device, the device will not be used if inhibited. It will be used if any of the other above conditions exist unless the Disable PLM Due to Linepack Stale flag is configured for the PLM record.

If a device reading cannot be used, a value of zero is saved as the delta volume for the current minute.

Note: Usability may or may not be a reflection of quality. For example, if a device is taken offline, it will be marked as inhibited. In this case, it is not usable but the zero value assigned to it is good quality, since it is known that there is no volume change in the region associated with the device.