Supporting four distinct leak test modes on one machine requires a flexible PLC sequencing architecture rather than hardcoding each test type separately. Here's the implementation pattern, described conceptually rather than in code.
Test Mode Configuration Schema
The system defines a TestMode enumeration with four members: STATIC_LEAK, PRESSURE_HOLD, STEPWISE, and REALTIME_PROFILE. Each mode has its own configuration structure.
A StaticLeakConfig holds the test pressure in bar, the hold time in seconds, and the maximum allowable pressure drop in bar.
A PressureHoldConfig holds the test pressure in bar, a hold time in seconds that is typically much longer (often hours), and a tolerance band in bar that the pressure must stay within throughout the hold.
A StepwiseConfig holds a list of pressure steps expressed as percentages of rated pressure (for example 25, 50, 75, 100), the rated pressure in bar, the hold time per step in seconds, and the maximum leak allowed per step in bar.
A RealtimeProfileConfig holds a pressure profile as a list of time-and-pressure pairs, plus a sample rate in hertz, defaulting to 10 Hz.
Unified Test Executor
A LeakTestExecutor class is initialized with a pressure controller and a sensor interface, and keeps a running results log. Its execute method takes a TestMode and a configuration object, and dispatches internally to one of four private methods based on the mode: _run_static_leak, _run_pressure_hold, _run_stepwise, or _run_realtime_profile.
For a static leak test, the executor pressurizes to the target pressure, isolates the circuit, and records pressure readings for the configured hold time. It computes the pressure drop as the difference between the first and last reading, and the test passes if that drop is at or below the configured maximum.
For a stepwise test, the executor loops through each percentage step, pressurizes to that step's target (a fraction of rated pressure), isolates, holds for the per-step hold time, and records the pressure drop for that step before venting and moving to the next step. Each step gets its own pass/fail result, and the overall test passes only if every step passes; any failing steps are reported by their percentage.
For a pressure hold test, the executor pressurizes to the test pressure, isolates, and continuously samples pressure across the full hold duration. The test passes if every reading stays within the tolerance band around the test pressure throughout the hold; minimum and maximum observed pressures are logged alongside the pass/fail result.
For a realtime profile test, the executor steps through a list of target time/pressure pairs, commanding each target pressure and reading back the actual pressure at that point, logging the error between target and actual for every point in the profile.
The Neometrix High Pressure Leak Testing Machine implements this unified test executor architecture across all four test modes, with PLC-based automation and touchscreen HMI for operator test programme selection.
https://neometrixgroup.com/products/high-pressure-leak-testing-machine
