The fields within this section of the Flow Calculation tab display properties associated with the calculation’s Differential Pressure input. The differential pressure section is only available when the Type of flow calculation is set to V-Cone, or one of the AGA-3 options.
You can configure these properties directly in Geo SCADA Expert, or read the configuration into the Geo SCADA Expert database (see Configure or Read the Flow Run Configuration).
- Input Type—Select the input type from the following list:
- Telepace Integer
- Float
- Raw Float
- ISaGRAF integer
- SCADASense 4202/4203 Internal.
The availability of the fields the rest of this section varies, depending on the input type.
- Input Register—Define the address of the register in the Flow Computer I/O database that contains the reading from the differential pressure sensor. For the selected Input Type the valid values are in the following ranges:
- 30001 to 39999 for Telepace Integer, Float, Raw Float and ISaGRAF integer
- 1 to 10
for Sensor.
This field is available for options other than the SCADASense 4202/4203 Internal.
- Input at Zero Scale—Specify the value read from the sensor when the sensor is at zero scale.
This field is available for options other than the Float, Sensor or SCADASense 4202/4203 Internal.
- Input at Full Scale—Specify the value read from the sensor units when the sensor is at full scale.
This field is available for options other than the Float, Sensor or SCADASense 4202/4203 Internal.
- Engineering Input at Zero Scale—Specify the differential pressure that corresponds to the zero scale input, or if the input does not require scaling (for Float input type), the minimum differential pressure that can be read from the sensor.
This field is available for options other than the SCADASense 4202/4203 Internal.
- Engineering Input at Full Scale—Specify the differential pressure that corresponds to the full-scale input, or if the input does not require scaling (for Float input type), the maximum differential pressure that can be read from the sensor.
This field is available for options other than the Sensor or SCADASense 4202/4203 Internal.
- Low DP Cutoff—Specify the scaled input differential pressure where flow accumulation will stop. Valid values depend on the sensor, (refer to the sensor user manual). The value should be less than the Upper Operating Limit (Engineering Input at Full Scale) and more than the Lower Operating Limit (Engineering Input at Zero Scale). The default value is 0.
- Low DP Hysteresis—Specify the amount, in percent of span, that the differential pressure needs to rise above the Low DP Cutoff to clear the low alarm and allow the flow calculations to resume.
- Default Value—Set the value for the input variable to use when any of the following conditions are met:
- The Input Type is set to Sensor or SCADASense 4202/4203 Internal and the Sensor Fail Values option in the Input Properties section is configured to Use Configured Defaults.
- When alarms are enabled and the Values in Alarm option on the Input Properties section is set to Use Default Values.
- Location—Define whether the location (latitude and elevation) of the flow is compensated for in the calculation or not.
The input alarms section of the Differential Pressure section allows you to set the alarm thresholds for alarm types that have been enabled in the Input Properties section.
Use the following to configure alarm limits in the Differential Pressure section:
- High-High Alarm Threshold—Set the high-high alarm threshold value for the differential pressure value. A valid entry value is any value within the differential pressure scale range that is higher than or equal to the value of High Alarm Threshold. The default is the Differential Pressure at Full Scale for analog inputs, or the Upper Operating Limit for sensors. This control is enabled if Use High-High Alarm option is enabled on the Input Properties section, otherwise this control is unavailable.
- High Alarm Threshold—Set a high alarm threshold for the differential pressure value. A valid entry is any value in the differential pressure scale range that is higher than the value of the Low Alarm Threshold, and is lower than or equal to the value of the High-High Alarm Threshold. The default is the Differential Pressure at Full Scale for analog inputs, or the Upper Operating Limit for sensors. This control is enabled if Use High Alarm option is enabled on the Input Properties section, otherwise the control is unavailable.
- Low Alarm Threshold—Set a low alarm threshold for the differential pressure value. A valid entry is any value in the differential pressure scale range that is lower than the value of the High Alarm Threshold. The default is the Differential Pressure at Full Scale for analog inputs, or the Upper Operating Limit for sensors. This control is enabled if the Use Low Alarm option is enabled on the Input Properties section, otherwise the control is unavailable.
- Alarm Hysteresis—Set the hysteresis value for each configured alarm type. The hysteresis setting determines at what level alarms are cleared when the input variable reading returns to a non-alarm state. This setting reduces nuisance alarms around the alarm threshold.
- Any value in the range 0 to 100 percent is valid when the Hysteresis Units are set for Percent, in the Input Properties section.
- Any value in the full-scale range of the input variable is valid when the Hysteresis Units is set to Engineering, on the Input Properties section.
Further Information
For more detailed information on these properties, see the documentation provided with the Realflo application.