How to Choose the Right One for Your Application
Every industrial application has specific requirements in terms of sensitivity, cycle speed, workpiece volume, and operating pressure.
There is no such thing as a universal leak tester: the choice of measurement technology depends on the type of component being tested, the acceptable leak rate, the setting (production or laboratory), and the level of automation required.
This table compares the 12 main technologies available to help you quickly identify the one that best suits your needs:
| Technology | Leakage [cc/min @ 1 Atm] | Pressure [Atm] | Part volume [cc] | Sensitivity | Ideal context |
|---|---|---|---|---|---|
| Compliance with interception | 0.01 – 0.5 | −0.95 – 250 | 1 – 500 | Extreme | Production, laboratories |
| Vacuum bell | 0.03 – 1 | −0.95 – 80 | 1 – 500 | Ultra high | Production of sealed parts |
| Differential microvalves | 0.05 – 1 | −0.95 – 6 | 1 – 10 | Ultra high | Production rapid cycles |
| Dual Absolute Zero Cent. | 0.1 – 10 | −0.95 – 21 | 00 – 10.000 | Ultra high | Production of identical parts |
| Differential | 0.1 – 7.5 | −0.95 – 25 | 1 – 1.000 | Ultra high | Production, laboratories |
| Dual Absolute Differential | 0.1 – 5 | −0.95 – 100 | 1 – 10.000 | Ultra high | High pressure, production |
| Absolute pressure decay | 0.3 – 25 | −0.95 – 250 | 10 – 100.000 | High | General production |
| Volumetric absolute pressure decay | 0.3 – 15 | −0.95 – 250 | 10 – 100.000 | High | Sealed parts in bell |
| Mass-Flow Differential | 0,5 – 50 | −0,95 – 6 | 1 – 100 | Ultra High | Laboratory |
| Micro-flow | 1 – 1.000 | −0,95 – 8 | 1 – 300 | Very High | Production, medium-low sealing |
| Flow | 5 – 50.000 | −0,95 – 16 | 1 – 1.000 | High | Production, flow testing |
| High-Flow | 100 – 100.000 | 0,0001 – 0,001 | 1.000 – 300.000 | High Flow | Big Volumes, Low Pressure |
Detailed Technical Data Sheets
In-depth overview of each technology: operating principle, field of application, limitations and critical design parameter.
Mass-Flow RFO
Mass flow meter equipped with a sophisticated automatic pressure regulation system directly inside the part. It compensates in real time for flow rate variations and pressure drops, dynamically adapting to test conditions.
Very large volumes with low test pressures, unstable dynamic conditions, high flow rates. Ideal when the part cannot be deformed by pressure.
Not ideal for micro-leaks or measurements requiring high mutual stability between successive tests.
Mass-Flow Continuous Flow
The part is continuously fed with an air stream while the mass-flow meter measures the flow rate. It can be equipped with electronic or manual precision regulation. Requires a stable, oscillation-free reference flow rate.
Passage measurements with rapid cycle times (filters, orifices), leak tests with medium-to-high leakage (cartridge valves, mufflers, household appliances). Automatic pressure compensation as flow rate varies.
Not suitable for micro-leaks where the resolution of continuous flow measurement is insufficient.
Mass-Flow MicroFlow
Continuous meter optimised for very low flow rates. The target is filled with a higher flow and, during the measurement phase, the reduced, continuous flow is monitored. No volumetric compensation required: particularly versatile.
Leak tests with medium-to-low leakage, direct real-time measurement. Versatile thanks to independence from the target volume.
Not ideal for very small micro-leaks or under conditions of supply pressure instability.
Differential Mass-Flow
Target and reference volume are pressurised during the fill phase; during measurement, the reference flow is discharged into the target, eliminating at source the fluctuations and distortions typical of continuous-flow systems. Precision comparable to that of a calibrator.
Laboratory and R&D. Leak tests where the highest metrological quality is required.
Measurement is not continuous. Requires target volume parameterisation and depends on the capacity of the reference volume.
Absolute Pressure Drop
Measures leakage through pressure decay over time using a single relative sensor. Electronic or manual pressure regulation. Intrinsically positive-safe system: it is the most widespread and proven method in industrial leak testing.
General-purpose applications requiring simplicity, practicality and reliability. Wide operating pressure range (up to 250 Atm).
Limited sensitivity compared to advanced systems. Pay attention to repeatability on elastic parts.
Volumetric Absolute Drop
Absolute drop equipped with a capacitive sensor to determine the cavity volume under measurement. Automatically calculates the volumetric leak and verifies the presence of the part in the bell chamber, avoiding false outcomes in the event of a missing part or a large leak.
Bell chamber tests for sealed parts. Detects the possible absence of the part or saturation of the bell chamber.
Superfluous if volume measurement is not required or if the part is not sealed.
Dual Absolute Zero Center
Mixed differential and absolute mode that exploits the maximum balance between two identical targets. Unlike traditional mechanical differential systems, it activates two independent absolute channels to avoid false accepts when both parts have similar leakage.
Production with identical parts at a constant rate. Halves test times. Ideal with similar thermal gradients between targets.
Not useful if the parts differ greatly in volume or geometry.
Differential
Differential pressure drop meter, available in mechanical (with differential transducer) or Dual Absolute version. Compares the pressure between the test volume and a reference sample volume to stabilise the measurement and compensate for ambient temperature variations.
Any application where precision is a priority. Requires careful setup. Suitable for both production and laboratory use.
If the acceptable leak value does not require differential sensitivity: the setup is more complex than the absolute drop approach.
Differential Dual Absolute
Evolution of the classic differential with programmable-interval sampling of the reference channel. Performs a vector differential with the test channel, reducing false repeatability errors caused by mechanical and thermal stress on the reference.
Differential tests even at very high pressures (up to 100 Atm) with the benefits of Dual Absolute technology.
More complex than basic systems. Identifying the correct reference sampling interval requires experience.
Differential Microvalves
Mechanical differential with no connection to an external reference volume (masterless). Thermally balanced within the measurement pneumatics. Equipped with a single equalising valve to eliminate switching transients and achieve maximum cycle speed.
Very small volume components with extremely fast cycle times. Ideal for micro-electronic components and connectors.
Not suitable for large parts. The speed advantage is lost for volumes greater than approximately 10 cc.
Vacuum Bell Chamber
Operates at negative pressure with a vacuum transducer, resistant to high positive pressure spikes in the event of a large leak. The part is pressurised internally and the leak is detected as a pressure rise in the vacuum bell chamber cavity.
Thanks to the double-port bell chamber (In and Out), it amplifies the positive pressure leak by measuring it externally. Ideal for sealed and complex parts.
Not suitable for traditional direct tests where an effective bell chamber cannot be realised.
Compliance with Interception
System composed of three branches: reading the leak from the bell chamber annular gap, injecting high pressure into the part, and injecting a sample leak for closure verification. Thanks to interception “at zero”, it offers the highest sensitivity possible among all pressure-variation systems, with a drastic reduction of spurious signals caused by thermal effects.
Where maximum sensitivity is essential: critical micro-leaks, valves, medical devices, safety components. Also available in Compliance In/Out mode with very short cycle times.
More complex setup. Requires excellent thermal and mechanical stability in the double-port bell chamber.