Understand Input Level Fraction, Strapping Fraction, and Display Level Format

AVEVA Pipeline Operations for Liquids provides the Administrator with the flexibility to have three separate configurations for level fractions, namely: Input Level Fraction, Strapping Fraction, and Display Level Format. This is useful for scenarios where a tank remote provides readings using a fraction that is different from the one used in the Tank Strapping configuration. Optionally, if you would like to use a display format for the level that varies from the input fraction and the strapping fraction, a different display level format can be specified. The following examples illustrate how these configurations are used.

Example 1

You have a tank that is configured as follows:

• Remote Type is set to Level (inc)

• Input Level Fraction is set to 1/8 inch

• Strapping Fraction is set to 1/16 inch

• Display Level Format is set to 100th foot

When the remote device reports a reading of 345, the following is expected:

Because the Input Level Fraction is set to 1/8 inch, the system will interpret the reading as 345 1/8-inch increments.

For the purpose of using the tank strapping configurations to perform level-to-volume lookups:

Because the Strapping Fraction is set to 1/16 inch, the system will convert the 1/8-inch increments to 1/16-inch increments

• Number of 1/16 inch-increments = 345 x 2 = 690 1/16-inch increments

  The system will then use 690 as the number of increments when performing a lookup in the strapping table to determine the volume in the tank.

For the purpose of displaying the level on ezXOS displays and alarm/event messages:

Because the Display Level Format is set to 100th foot, the system will convert 690 1/16-inch increments to 100th-foot increments.

• Number of 100th-foot increments = (690 / 16 / 12) x 100 = 359 100th-foot increments

  The system will use 359 increments to format the level:

• Display Level = 359/100 = 3.59 feet

Example 2

You have a tank that is configured as follows:

• Source Type is set to Analog

• Remote Type is set to Level (eng units)

• Input Level Fraction is set to 1/8 inch

• Strapping Fraction is set to 1/16 inch

• Display Level Format is set to 1/32 inch

When the source analog reports a reading of 3.59, the following is expected:

Because the Input Level Fraction is in imperial units, the system will interpret the analog reading as 3.59 feet. The system will convert the reading into a number of 1/8-inch increments:

• Number of 1/8-inch Increments = 3.59 feet x 12 inches per foot x 8 increments per inch = 3.59 x 12 x 8 = 345 1/8-inch increments

For the purpose of using the tank strapping configurations to perform level to volume lookups:

Because the Strapping Fraction is set to 1/16 inch, the system will convert the 1/8-inch increments to 1/16-inch increments:

• Number of 1/16 inch-increments = 345 x 2 = 690 1/16-inch increments

  The system will then use 690 as the number of increments when performing a lookup in the strapping table to determine the volume in the tank.

For the purpose of displaying the level on ezXOS displays and alarm/event messages:

Because the Display Level Format is set to 1/32 inch, the system will convert 690 1/16-inch increments to 1/32-inch increments.

• Number of 1/32-inch increments = 690 x 2 = 1,380 1/32-inch increments

  The system will use 1,380 increments to format the level accordingly:

• Number of inches = 1,380 / 32 = 43.125 inches

• Feet portion = 43.125 / 12 = 3 feet

• Inches portion = 43.125 - (12 x 3) = 7 inches

• Fractions portion = (43.125 - (12 x 3) - 7) x 32 = 4 fractions

• Display Level = 03-07-04 (FTT-IN-32)

  For more information on configurations, refer to the descriptions for Input Level Fraction, Strapping Fraction and Display Level Format fields as defined within the previous sections.