Tank Management terminology

% Full

The percent amount by which the tank is full.

Alarm Inhibit

This field indicates whether or not alarms are inhibited for the tank.

Alarm Reset

To reset all period alarms, select Alarm Reset.

Auto Idle

The idle state of a tank can be defined by one of two conditions. A tank can be manually marked idle by you, or it can be automatically marked idle based on up to ten comparisons corresponding to the Value of the analog point or the State of the status or multistate point. Deviation alarms are based on the idle state of the tank. To enable AVEVA Enterprise SCADA to declare the tank idle based on the comparison results of the analog point’s valve against the configured value or status / multistate’s state against the configured state:

In the Auto Idle section of the Tank Control dialog, select Auto Idle.

If all comparisons are true, then the tank will be declared idle after the user-configured time period (configured to allow for settling) has passed.

To prevent AVEVA Enterprise SCADA from declaring the tank idle when all of the comparisons succeed, clear the Auto Idle checkbox.

Avg GOV Flow Rate

The average Gross Observed Volume (GOV) flow rate based on tank level changes where:

Note: The Elapsed Time is configured by the Administrator.

Avg GSV Flow Rate

The average Gross Standard Volume (GSV) flow rate, calculated by correcting the Avg GOV Flow Rate to standard temperature where:

Clear Resettable Values

To reset the indicated and gross standard resettable counters, select Clear Resettable Values.

The counters are reset to zero and the application resumes counting. However, when the resettable counters reach the value displayed in the Rollover field, they are reset automatically.

Corrected

The corrected gravity value used to correct the volume to American Petroleum Institute (API) standards.

Correct Factor

The Correction for Temperature of a Liquid (CTL).

Counter Type

The counter type is set by the Administrator. Counters count the input, output, or sum of both input and output.

Creep Alarms

Select Enable to make AVEVA Enterprise SCADA generate an alarm when the level of an idle tank deviates from the saved level by more than the amount entered in the + Deviation or - Deviation fields.

When a tank is marked as idle, the current level is saved. If the level in the tank deviates from the saved level by more than the configured amounts (+ Deviation and - Deviation), AVEVA Enterprise SCADA generates a deviation alarm and saves the new level.

(This new level now becomes the reference level for future deviation alarms.) This does not remove any current deviation alarm. The current deviation alarm must be acknowledged separately.

Creep Level

The base level for creep alarm checking.

Current (API Density)

The current, corrected API density in the tank.

Current (Density)

The current density in the tank.

Current (Temperature)

The current temperature in the tank.

Current GOV

The Gross Observed Volume (GOV) of product in the tank. The GOV is calculated by converting tank level via a volume conversion table (strapping table).

Current Gross Standard Volume (GSV)

Current volume corrected to standard temperature and pressure.

Current (Snow Load)

The current snow load weight in the tank.

Current State

The current state of the tank.

Deadband

Deadband can be defined as the minimum percentage of a given range or amount by which a measured value must vary in order for the device to register a change.

If a tank enters an alarm state, AVEVA Enterprise SCADA will not consider it as having returned to a normal state until the volume changes by more than this deadband value. The deadband value prevents alarms from being generated due to minor fluctuations in volume.

Density

Density is a property of matter that accounts for mass per unit of volume.

Density: Manual Override

To use a manually entered, observed density value.

Density Type

The density used to correct the volume to API standards can come from a number of sources. The Density Type field defines which source will be used.

Use the guide below to select a density type.

• If the density selection is set to Product table, the API density is determined from the product in the tank.

• If the density selection is set to Use entered API, then a manually-specified, corrected API density is used. (This should not be confused with a manually overridden, observed density described above, which can be used only when an uncorrected density is known.)

• If the density selection is set to Use Observed, then AVEVA Enterprise SCADA uses the observed value from the tank's density analog point. This observed value can either be telemetered or manually entered.

• Select Submit after selecting a density type.

Enable Counters

To turn on the counters, select Enable Counters (gross observed or gross standard).

Ending

The ending accumulator reading.

ETA (GOV target)

This field displays the estimated time the volume target will be reached. The ETA is displayed as the date and time of day in MMDDYYhhmmss format.

ETA (GSV target)

The estimated time at which the volume target will be reached.

ETA (Volume)

The estimated time at which the volume target will be reached. The ETA is displayed as the date and time of day in the above format.

GOV

The Gross Observed Volume (GOV) of product in the tank. The GOV is calculated by converting the tank level via a volume conversion table (strapping table).

GOV Flow Rate

The instantaneous GOV flow rate based on tank level changes where:

GOV Target

The gross observed (uncorrected) target volume.

GOV to Fill

The volume of space remaining in the tank. The current standard/indicated volume in the tank is subtracted from the configured maximum safe tank volume to calculate the volume to fill. If the volume in the tank is larger than the maximum safe volume, the volume to fill is negative.

GOV to Pump

The volume of liquid in a tank, excluding the tank bottom volume. The configured tank bottom volume (gross standard or indicated depending on the tank type) is subtracted from the current gross standard/indicated volume to calculate the volume of liquid that can be safely pumped from the tank.

Group

The group to which this tank belongs.

GSV

Gross Standard Volume (GSV) (that is, GOV corrected to standard temperature).

GSV Change

The resettable GSV counter.

GSV Flow Rate

The instantaneous Gross Standard Volume flow rate, calculated by correcting the instantaneous GOV Flow Rate to standard temperature where:

GSV Target

The gross standard (corrected) target volume.

HiHi/LoLo, Hi/Lo, Normal Fill, Normal Empty, User Hi / User Lo Alarms

To enable, select Enable to make the system generate an alarm when the tank level either exceeds the HiHi, Hi, Normal Fill or User Hi limit or falls below the LoLo, Lo, Normal Empty or User Lo limit.

Inhibit

To stop the counter, select Inhibit.

Instrument Fail Alarm

AVEVA Enterprise SCADA declares an instrument/transducer fail high or fail low alarm when:

• The input value at the Remote Terminal Unit (RTU) is outside of the field instrument’s measurable range.

• The level reading is negative or has exceeded the Maximum Physical Level.

  AVEVA Enterprise SCADA declares a Return-to-Normal alarm when:

• The input value returns within the range of the instrument/transducer fail high and fails low alarm limits.

• The level reading is within the normal physical boundaries of the tank.

  Instrument/transducer failure alarms take precedence over HIGH-HIGH/LOW-LOW alarms and over HIGH/LOW alarms. These are RTU-specific alarms and may not be supported in some systems. However, if your Administrator has enabled the attribute-based instrument failure alarm functionality (that is, by using the INSTR_FAIL_AS_ATTRIBUTE setting), the alarm can co-exist with a state-based HIGH-LOW alarm (HIGH-HIGH, LOW-LOW, and so on).

  Select Enable to enable Instrument Fail alarming.

Man Dens

The field indicates whether or not the density is a manually entered value. For more information, see Open the Tank Manual Overrides dialog.

Man Temp

Indicates whether or not the temperature is a manually entered value.

Man. (temperature)

Indicates whether or not the observed temperature is a manually entered value.

Max Allowed

The maximum safe level for liquid in the tank.

Max GOV

The maximum volume that can be safely held in the tank.

MCF

The Meter Correction Factor.

Min GOV

The minimum volume that can be safely held in the tank.

Mixers 1–5

Turns a mixer on or off.

New Type

The product type currently contained in the tank.

New Value (API Density)

Manually specify a corrected API density.

New Value (Snow Load)

There is no telemetered value for the tank snow load. However, you can enter a snow load weight manually.

Observed

The telemetered or manually entered density.

Operator Idle (Tank Control)

The idle state of a tank can be defined by one of two conditions. You can manually mark a tank idle on the Tank Control dialog, or it can be automatically marked idle based on up to ten comparisons corresponding to the Value of the analog point or the State of the status or multistate point. Deviation alarms are based on the idle state of the tank.

Operator Idle (Tank Detail)

This field indicates whether or not you have manually forced the tank into the idle state.

Override (Density)

This field indicates whether or not the density is a manually entered value.

Percent Full

The percent amount by which the tank is full.

Product

The product type currently contained in the tank.

Pumpable Volume

This volume is the volume of space remaining in the tank.

The current standard/indicated volume in the tank is subtracted from the configured maximum safe tank volume to calculate the volume to fill.

If the volume in the tank is larger than the maximum safe volume, the volume to fill is negative.

Remain

The distance between the current fill level and the maximum safe fill level. This distance decreases as the tank fills, and increases as the tank empties.

Remaining Volume

The volume of space remaining in the tank.

The current standard/indicated volume in the tank is subtracted from the configured maximum safe tank volume to calculate the volume to fill.

If the volume in the tank is larger than the maximum safe volume, the volume to fill is negative.

Reset Accumulation Counters

The resettable counter is reset only on your command or when it reaches the software rollover value. To reset the counter to zero, select Reset Accumulation Counters.

Reset Periodic Integration Counters

Select Reset Periodic Integration Counters to reset the hourly, daily, weekly, monthly, and yearly counts to zero.

Resettable Counter Information

The current counts for gross observed and gross standard volume appear in the Hourly, Daily, Weekly, Monthly and Yearly fields.

Rate of Change Alarming > Enabled

When the Rate of Change Alarms > Enabled is selected, an AVEVA Enterprise SCADA non-persistent alarm may be generated when the Rate of Change (ROC) of the tank volume exceeds specified limits.

Rate of Change Inhibit

This inhibit will suppress AVEVA Enterprise SCADA from generating a non-persistent alarm when the ROC of the tank volume exceeds the specified limits.

Filling ROC Limit (Units/Hr)

The filling ROC limit. If the flow rate exceeds this limit, the tank will then be in an ROC Alarm state.

Emptying ROC Limit (Units/Hr)

The emptying ROC limit. If the flow rate exceeds this limit, the tank will then be in an ROC Alarm state.

Rollover

The value at which the resettable counter rolls over. This is used for both the GO and GSV. When the daily and monthly rollover occurs, the counter information is sent to the Historical database.

RTU

The name of the RTU unit the controls the point.

Scratch Pad

The scratch pad gives you the ability to convert a tank level to a tank volume and vice versa, based on the strapping table, snow load and roof correction.

Smoothed GOV Flow Rate

The average GOV flow rate based on a Basic Exponential Smoothing filter, calculated as follows:

Smoothed GSV Flow Rate

The average GSV flow rate based on a Basic Exponential Smoothing filter, calculated by correcting the Smoothed GOV Flow Rate to standard temperature where:

Snow Load

The snow load factor is used to compensate for the effect of the roof on the volume of the tank.

State

The current state of the tank.

Status

Indicates whether the tank is in a normal or an alarm state.

Status Outputs:

• Inactive

• Receiving

• Delivering

• Floating

Strap Fraction

This field displays the level units used for the strapping table.

The strapping table maps total volume to a specific level or increment, and is used to convert a tank level reading into a volume.

Strap Type

This field displays the level units used for the strapping table. The strapping table maps total volume to a specific level or increment, and is used to convert a tank level reading into a volume. For information about configuring the strapping table, refer to the AVEVA Pipeline Operations for Liquids Administrator documentation.

Tank Idle

This field indicates whether or not the tank’s defined comparisons have succeeded.

Tank Level: Manual Override, Override

Using a manually entered tank level value.

Tank Override

Indicates whether or not a tank override value is in effect for this record.

Temperature: Manual Override, Override

Use a manually entered temperature value.

Temp Factor

The temperature correction factor.

Time to Empty/Fill

The time that it should take to fill or empty the tank at the current flow rate.

Time to Target (GOV)

The number of minutes of warning time before the GOV target volume is reached.

Time to Target (GSV)

The number of minutes of warning time before the GSV target volume is reached.

Top of Day (TOD)

The time of day when the system should transition from one day to the next.

Type (density)

The source of the density and/or gravity used to correct the volume to API standards.

Vol to Fill

The volume of space remaining in the tank. The current standard/indicated volume in the tank is subtracted from the configured maximum safe tank volume to calculate the volume to fill.

If the volume in the tank is larger than the maximum safe volume, the volume to fill is negative.

Vol to Pump

The volume of liquid in a tank, excluding the tank bottom volume. The configured tank bottom volume (gross standard or indicated depending on the tank type) is subtracted from the current gross standard/indicated volume to calculate the volume of liquid that can be safely pumped from the tank.

Vol Type

Indicates whether the tank record uses GOV or GSV.

Volume

The GOV of product in the tank. The GOV is calculated by converting the tank level via a volume conversion table (strapping table).

Volume Type (Operator Tracking)

Allows you to specify whether the volume being tracked is a gross volume or a net volume.