DIFF_PRESS_DP

Overview

Calculate non-recoverable pressure drop across a differential pressure flow meter.

Excel Usage

=DIFF_PRESS_DP(D, D_two, P_one, P_two, C, dp_meter_type)
  • D (float, required): Upstream internal pipe diameter (m)
  • D_two (float, required): Meter characteristic diameter - orifice hole, venturi throat, cone end, or wedge height (m)
  • P_one (float, required): Static pressure upstream at pressure tap (Pa)
  • P_two (float, required): Static pressure downstream at pressure tap (Pa)
  • C (float, optional, default: 0.6): Coefficient of discharge (required for orifice plates and venturi nozzles) (-)
  • dp_meter_type (str, optional, default: “ISO 5167 orifice”): Type of differential pressure flow meter

Returns (float): Non-recoverable pressure drop of the flow meter (Pa)

Examples

Example 1: As-cast venturi tube pressure drop

Inputs:

D D_two P_one P_two dp_meter_type
0.07366 0.05 200000 183000 as cast convergent venturi tube

Excel formula:

=DIFF_PRESS_DP(0.07366, 0.05, 200000, 183000, "as cast convergent venturi tube")

Expected output:

Result
1788.5718

Example 2: Cone meter pressure drop

Inputs:

D D_two P_one P_two dp_meter_type
0.25 0.18 1000000 950000 cone meter

Excel formula:

=DIFF_PRESS_DP(0.25, 0.18, 1000000, 950000, "cone meter")

Expected output:

Result
26289.9543

Example 3: Wedge meter pressure drop

Inputs:

D D_two P_one P_two dp_meter_type
0.2 0.14 1000000 950000 wedge meter

Excel formula:

=DIFF_PRESS_DP(0.2, 0.14, 1000000, 950000, "wedge meter")

Expected output:

Result
20344.8497

Example 4: Orifice with discharge coefficient

Inputs:

D D_two P_one P_two C dp_meter_type
0.1 0.05 150000 145000 0.61 ISO 5167 orifice

Excel formula:

=DIFF_PRESS_DP(0.1, 0.05, 150000, 145000, 0.61, "ISO 5167 orifice")

Expected output:

Result
3653.6377

Python Code

import micropip
await micropip.install(["fluids"])
from fluids.flow_meter import differential_pressure_meter_dP

def diff_press_dp(D, D_two, P_one, P_two, C=0.6, dp_meter_type='ISO 5167 orifice'):
    """
    Calculate non-recoverable pressure drop across a differential pressure flow meter.

    See: https://fluids.readthedocs.io/fluids.flow_meter.html#fluids.flow_meter.differential_pressure_meter_dP

    This example function is provided as-is without any representation of accuracy.

    Args:
        D (float): Upstream internal pipe diameter (m)
        D_two (float): Meter characteristic diameter - orifice hole, venturi throat, cone end, or wedge height (m)
        P_one (float): Static pressure upstream at pressure tap (Pa)
        P_two (float): Static pressure downstream at pressure tap (Pa)
        C (float, optional): Coefficient of discharge (required for orifice plates and venturi nozzles) (-) Default is 0.6.
        dp_meter_type (str, optional): Type of differential pressure flow meter Valid options: ISO 5167 Orifice, Orifice, Conical Orifice, Eccentric Orifice, Segmental Orifice, Quarter Circle Orifice, Venturi Nozzle, ISA 1932 Nozzle, Long Radius Nozzle, Machined Convergent Venturi Tube, Rough Welded Convergent Venturi Tube, As Cast Convergent Venturi Tube, Cone Meter, Wedge Meter. Default is 'ISO 5167 orifice'.

    Returns:
        float: Non-recoverable pressure drop of the flow meter (Pa)
    """
    if D <= 0:
        return "Error: D (upstream diameter) must be positive."
    if D_two <= 0:
        return "Error: D_two (meter diameter) must be positive."
    try:
        result = differential_pressure_meter_dP(
            D=D,
            D2=D_two,
            P1=P_one,
            P2=P_two,
            C=C,
            meter_type=dp_meter_type
        )
        return float(result)
    except Exception as e:
        return f"Error: {str(e)}"

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