Prove Actual Airflow with Precision & Absolute Compliance

Appliance data plates and fan curves are purely theoretical. Duct friction, damper positions, and dirty filters drastically alter real-world airflow. GasCalc provides indisputable mathematical proof of actual airflow in the field using either duct velocity traverses or complex stoichiometric flue gas analysis, ensuring your commissioning workflow is strictly compliant with AS 3814 and state regulations.

See How It Works

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Core Capabilities & Calculations

Two Verification Methods

Choose between physical Velocity measurement (perfect for pre-purge verification before gas is introduced) or Flue Gas Analysis (for exact high/low-fire combustion verification).

Advanced AS 1375 Chemistry

Standard field analysers remove water vapour, shrinking the sample volume. This tool automatically applies the "Dry Gas Shrinkage" parameters outlined in AS 1375, ensuring your O₂ dilution calculations are stoichiometrically exact.

Failsafe Purge Flow Proof

Confidently prove you have met the strict 25% minimum purge flow rule required by AS 3814, preventing explosive start-up failures and safeguarding your compliance status.

Audit-Ready Vector PDF Reporting

Data-Driven Compliance

Generates a complete, JSON-driven mathematical audit trail showing every calculation step for your commissioning report.

Field-Optimized Interface

Features a high-contrast "gloved mode" UI, allowing you to quickly input duct dimensions, velocity traverses, or measured O₂ percentages directly from the plant room.

Instant Documentation

Outputs crisp, vector-based PDF reports directly from the field, perfectly formatted for immediate submission to Technical Regulators.

How the Calculator Works

The Airflow Rate calculator processes your field measurements to generate indisputable proof of airflow.

1

Select Your Method

Choose between Method 1 (Duct Velocity) or Method 2 (Flue Gas O₂ Dilution) based on your commissioning stage.

2

Input Field Data

For Method 1, input duct dimensions and average velocity. For Method 2, input the measured gas flow rate, gas type, and stable O₂ reading from your analyser.

3

Generate Compliance Trail

The calculator instantly provides your actual airflow (m³/h) and generates a complete mathematical audit trail showing every calculation step for your commissioning report.

Legislative Framework

AS 3814:2018, Cl 2.20.2.2(b): Mandates that mechanical pre-purge flow rates must be not less than 25% of the maximum combustion air flow rate.

AS 3814:2018, Table 3.2: Specifies the baseline stoichiometric ratios and lower explosive limits (LEL) for common gases.

AS 1375:2023, Cl 3.8.3(b): Reaffirms that purging flow rates shall not be less than 25% of the maximum combustion air flow.

AS 1375:2023, App G, Fig G.3: Establishes that gas constituent percentages in flue analysis are calculated on a dry basis to align with analyser readings where water vapour has condensed out.

State Regulations: The WA Gas Standards Regulations 1999 (Reg 32(1)(b)), VIC Gas Safety Regulations 2018 (Reg 13), and SA Gas Regulations 2012 (Reg 43(1)(a)) strictly enforce compliance with AS 3814 for Type B appliance installations.

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