DIFF_PRESS_BETA
This function computes the differential-pressure meter beta ratio, which is the normalized meter opening size relative to the upstream pipe diameter. The beta ratio depends on meter geometry and is used in discharge and pressure-drop correlations for orifice plates, venturi meters, cone meters, and wedge meters.
In general, beta is defined as the ratio of a characteristic meter dimension to the pipe diameter:
\beta = \frac{D_2}{D}
For some meter types, such as cone and wedge meters, the implementation uses the meter-specific geometric definition from the underlying library.
Excel Usage
=DIFF_PRESS_BETA(D, D_two, beta_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)beta_meter_type(str, optional, default: “ISO 5167 orifice”): Type of differential pressure flow meter
Returns (float): Differential pressure meter diameter ratio (beta) (-)
Example 1: Standard orifice beta ratio
Inputs:
| D | D_two | beta_meter_type |
|---|---|---|
| 0.1 | 0.05 | ISO 5167 orifice |
Excel formula:
=DIFF_PRESS_BETA(0.1, 0.05, "ISO 5167 orifice")Expected output:
0.5
Example 2: Venturi tube beta ratio
Inputs:
| D | D_two | beta_meter_type |
|---|---|---|
| 0.2 | 0.12 | machined convergent venturi tube |
Excel formula:
=DIFF_PRESS_BETA(0.2, 0.12, "machined convergent venturi tube")Expected output:
0.6
Example 3: Cone meter beta ratio (uses special formula)
Inputs:
| D | D_two | beta_meter_type |
|---|---|---|
| 0.2575 | 0.184 | cone meter |
Excel formula:
=DIFF_PRESS_BETA(0.2575, 0.184, "cone meter")Expected output:
0.699571
Example 4: Wedge meter beta ratio (uses special formula)
Inputs:
| D | D_two | beta_meter_type |
|---|---|---|
| 0.2027 | 0.0608 | wedge meter |
Excel formula:
=DIFF_PRESS_BETA(0.2027, 0.0608, "wedge meter")Expected output:
0.502253
Python Code
Show Code
from fluids.flow_meter import differential_pressure_meter_beta
def diff_press_beta(D, D_two, beta_meter_type='ISO 5167 orifice'):
"""
Calculate the beta ratio (diameter ratio) for a differential pressure flow meter.
See: https://fluids.readthedocs.io/fluids.flow_meter.html#fluids.flow_meter.differential_pressure_meter_beta
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)
beta_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, ISO 15377 Conical Orifice, ISO 15377 Eccentric Orifice, ISO 15377 Quarter-circle Orifice, Miller Orifice, Miller Conical Orifice, Miller Eccentric Orifice, Miller Segmental Orifice, Miller Quarter Circle Orifice, Hollingshead Orifice, Venturi Nozzle, ISA 1932 Nozzle, Long Radius Nozzle, Machined Convergent Venturi Tube, Rough Welded Convergent Venturi Tube, As Cast Convergent Venturi Tube, Hollingshead Venturi Smooth, Hollingshead Venturi Sharp, Cone Meter, Hollingshead V Cone, Wedge Meter, Hollingshead Wedge, Unspecified Meter. Default is 'ISO 5167 orifice'.
Returns:
float: Differential pressure meter diameter ratio (beta) (-)
"""
try:
if D <= 0:
return "Error: D (upstream diameter) must be positive."
if D_two <= 0:
return "Error: D_two (meter diameter) must be positive."
result = differential_pressure_meter_beta(
D=D,
D2=D_two,
meter_type=beta_meter_type
)
return float(result)
except Exception as e:
return f"Error: {str(e)}"