neqsim-noise-screening

name	neqsim-noise-screening
version	0.1.0
description	Educational valve and line aerodynamic-noise indicator that estimates a screening sound-pressure level from gas mass flow, pressure drop, and density using a public IEC 60534-8 style energy approach. USE WHEN: a task needs a public, screening-level noise indicator and an action/high flag for a gas valve or restriction before detailed IEC 60534-8 noise prediction.
last_verified	2026-06-18
requires	{"python_packages":[],"java_packages":[],"env":[],"network":[]}

Noise Screening

Use this skill for public, educational aerodynamic-noise screening of a gas valve or line restriction. It estimates a sound-pressure-level indicator from the mass flow, pressure drop, and density using an open energy-based approach, so an agent can flag a potential noise problem before detailed IEC 60534-8 prediction.

When to Use

• When a user asks whether a gas valve or restriction is likely to be noisy.
• When an agent needs a quick action/high noise flag for screening.
• When examples must run without confidential valve trim or vendor noise data.

Inputs

• mass_flow: gas mass flow in kg/s.
• pressure_drop: pressure drop across the restriction in bar.
• inlet_density: inlet gas density in kg/m3.
• sound_speed: speed of sound in m/s (provide this, or temperature and molar mass).
• specific_heat_ratio: ratio of specific heats k, default 1.3.
• temperature: gas temperature in K (used to estimate sound speed).
• molar_mass: gas molar mass in g/mol (used to estimate sound speed).

Outputs

• vena_contracta_velocity_m_s: estimated velocity at the restriction.
• mach_number: velocity divided by the speed of sound.
• internal_sound_power_level_db: internal sound power level (re 1 pW).
• estimated_spl_1m_dba: screening sound-pressure level at 1 m.
• noise_warning: ok, action, or high.
• assumptions: public assumptions used by the placeholder model.

Engineering Method

The Python class ValveNoiseModel uses a public energy-based aerodynamic-noise approach:

• the vena-contracta velocity uses v = sqrt(2 * dP / rho).
• the speed of sound uses the provided value or c = sqrt(k * R * T / M).
• the mechanical stream power uses W_m = 0.5 * mdot * v^2.
• the acoustic power uses W_a = min(0.01, eta_f * Mach^3) * W_m.
• the sound power level uses L_W = 10 log10(W_a / 1 pW) and a fixed transmission loss converts it to a 1 m sound-pressure level.

This is an educational screening indicator, not a full IEC 60534-8-3 prediction. It uses a generic acoustic efficiency and a fixed transmission loss with no valve style, trim, pipe schedule, distance correction, or frequency weighting. It is not a replacement for validated noise prediction, vendor noise data, and qualified acoustic review.

Python Usage Pattern

from noise_screening import ValveNoiseModel

model = ValveNoiseModel()
result = model.evaluate(
    mass_flow=12.0,
    pressure_drop=40.0,
    inlet_density=35.0,
    temperature=310.0,
    molar_mass=19.0,
)

print(result.mach_number)
print(result.estimated_spl_1m_dba)
print(result.noise_warning)

Related NeqSim Functionality

For validated valve behaviour, redirect to existing NeqSim classes:

• neqsim.process.equipment.valve.ThrottlingValve — flow-vs-Cv valve and pressure-drop response that defines the noise duty.
• neqsim.process.equipment.valve.ControlValve — control valve with characteristic and controller coupling.

Full aerodynamic-noise prediction follows IEC 60534-8-3. This skill is a public noise triage layer that decides when to invoke detailed valve and noise tools.

Validation Checklist

• Mass flow, pressure drop, and density are positive.
• Either a sound speed or temperature and molar mass are supplied.
• The result is treated as a screening indicator, not a certified noise level.
• Tests cover the basic indicator, a high-noise case, sound-speed estimation, and invalid input.
• Real noise prediction is redirected to validated tools and qualified acoustic review.

Common Mistakes

Symptom	Cause	Fix
SPL looks too precise	Treated indicator as IEC result	Use it only for screening
Mach off	Sound speed from wrong gas	Provide molar mass and temperature
Wrong magnitude	Mass flow in kg/h not kg/s	Use kg/s

Limitations

• Screening indicator only, not IEC 60534-8-3 prediction.
• No valve style, trim, pipe schedule, or frequency content.
• Fixed transmission loss and generic acoustic efficiency.

References

• NeqSim repository: https://github.com/equinor/neqsim
• NeqSim Skills Guide: https://github.com/equinor/neqsim/blob/master/docs/integration/skills_guide.md