Steam Flow Calculator (ISO 5167)

This industrial-grade calculator determines the Mass Flow Rate ($q_m$) of Saturated Steam through an orifice plate. It strictly adheres to ISO 5167-2 standards, featuring Thermal Expansion Correction ($F_a$), Permanent Pressure Loss calculation, and high-precision saturated steam properties ($R^2 > 0.999$).

1. Geometry & Material

Pipe Inner Diameter ($D$) [in]

Orifice Bore ($d$) [in]

Orifice Plate Material

Tapping Arrangement

2. Process Conditions (Saturated Steam)

Upstream Pressure ($P_1$) [psig]

Differential Pressure ($\Delta P$) [inH2O]

Isentropic Exponent ($\kappa$)

Flow Calculation Summary

Parameter	Value

Professional Insights: ISO 5167 & Steam Measurement

Thermal Expansion ($F_a$)

Orifice plates are machined at room temperature ($20^\circ$C). When measuring steam at $185^\circ$C (150 psig), the metal expands, making the bore diameter ($d$) slightly larger.

While the change seems small (e.g., +0.25%), because flow is proportional to $d^2$, the impact on flow measurement is significant ($\approx 0.5\%$). This calculator automatically applies the Area Thermal Expansion Factor ($F_a$) based on the selected material properties.

Permanent Pressure Loss (PPL)

An orifice plate creates a restriction that converts pressure energy into kinetic energy ($\Delta P$). However, not all pressure is recovered downstream. The turbulence creates an unrecoverable energy loss called Permanent Pressure Loss ($\Delta \varpi$).

PPL is roughly proportional to $1 - \beta^2$. A smaller Beta ratio (smaller hole) causes significantly higher energy loss, which increases pump/boiler operating costs. A high PPL also requires checking the pump head capacity.

ISO 5167-2 Validity

The Stolz equation used here is the global standard for orifice sizing. To ensure accuracy ($\approx 0.5 - 1.0\%$), your installation must meet specific criteria:

$d \ge 12.5$ mm ($0.5$ in)
$50$ mm $\le D \le 1000$ mm ($2$ in to $40$ in)
$0.1 \le \beta \le 0.75$
$Re_D \ge 5000$