# C150 – Upstream Density Calculation

## Description

This calculation corrects the density to upstream conditions.

## References

IP Petroleum Measurement Manuel: Part VII Section 2: Continuous Density Measurement

Implementation of ISO 5167:2003 at Gas Terminals for Sales Gas Metering Systems using Densitometers in the ‘bypass’ mode. Dti March 2007.

Kelton calculation reference C150

FLOCALC calculation reference F037

KIMS calculation reference K151

## Options

### Method

- Density exponent

This option calculates the upstream density using either the density or isentropic exponent as an input.

- Isenthalpic

This option calculates the upstream density using upstream and downstream temperatures and compressibility as inputs.

### Density correction exponent

- Calculate from isentropic exponent

Check the box if you want to enter the isentropic exponent for use in the calculation.

## Calculation

All calculations are performed in SI units unless otherwise stated.

### Upstream density

When density exponent is the selcted method, the upstream density is calculated by:

Where

ρ | = | Downstream density |

p_{1} |
= | Upstream pressure |

Δp | = | Differential pressure |

E_{d} |
= | Density exponent |

κ | = | Isentropic exponent |

When isenthalpic is the selected method, the upstream density is calculated by:

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

ρ | = | Downstream density (measured density at P2 T3 from the densitometer in bypass mode) |

p_{1} |
= | Upstream pressure |

Δp | = | Differential pressure |

T_{1} |
= | Upstream temperature |

T_{3} |
= | Measured temperature at the downstream recovery point |

Z_{1} |
= | AGA 8 Compressibility at P_{1},T_{1} |

Z_{3} |
= | AGA 8 Compressibility at P_{2},T_{3} |