# C244 – Calibration Correction

## Description

This calculation corrects results to calibration certificate data by performing a linear interpolation between reference (calibration) values.

## References

Kelton calculation reference C244

## Options

### Primary variable

- Pressure
- Temperature
- Volume flow rate
- Mass flow rate

This option is used to select the type of value that is to have a calibration correction applied.

### Calibration Points

- Rising/Falling

This option is selected if a calibration is to be carried out from low to high and high to low values.

### Calibration Correction

This option allows selection of how many data points there are for each footprint.

### Output type

- Digital
- Analogue

This option is used to select whether the output is analogue or digital.

##### If the output is digital the following options will be available:

### Correction Type

- Correction Factor
- Correction Value
- Error (Difference)
- Error (% Actual)
- Error (% Reading)

This option is used to specify the correction type being used for the calibration correction.

### Interpolate On

- Absolute Value
- Correction Factor

This option is used to select whether interpolation will be done about absolute values or correction factors.

If Error (%Actual) is selected there is an addition option to interpolate on the % Error. In this case the actual % error is interpolated on rather than the variable itself then this % error is applied to the input variable as a % of actual value.

##### If the output is analogue the following options will be available:

### Output Variable

- Voltage
- Current

This option is used to select whether the analogue output is a voltage or a current.

### Calibration Values

- Enter calibration values as % of maximum flow rate

If mass or volume flow rate are the primary variable then this option allows the calibration values to be enter as a percentage of the maximum flow rate specified for the meter.

## Calculation

If interpolate on absolute value is selected the correction type is converted to an absolute correction value.

### Correction Factor

For a correction factor this is done by:

### Error (Difference)

If error (difference) is the selected correction type then:

### Error (% Actual)

If error (% actual) is the selected correction type then:

### Error (% Reading)

If error (% reading) is the selected correction type then:

If interpolate on correction factor is selected then the correction type is converted to a correction factor for interpolation.

### Correction Value

For a correction value this is done by:

### Error (Difference)

If error (difference) is the selected correction type then:

### Error (% Actual)

If error (% actual) is the selected correction type then:

### Error (% Reading)

If error (% reading) is the selected correction type then:

Where | ||
---|---|---|

FP_{x} |
= | Reference values |

CV_{x} |
= | Correction values corresponding to footprint |

CF_{x} |
= | Correction factors corresponding to footprint |

EΔ | = | Error (difference) values corresponding to footprint |

EA_{x} |
= | Error (% actual) values corresponding to footprint |

ER | = | Error (% reading) values corresponding to footprint |

### Corrected Output

The corrected output is calculated using linear interpolation.