Five Questions to Define Your Leak Test Requirement
Selecting the correct leak tester starts with answering five application-specific questions. Getting these right before evaluating instruments eliminates the risk of under-specifying sensitivity or over-specifying cost.
1. What is your test pressure range?
Test pressure is typically set at 80–120% of the component's maximum working pressure. For EV cooling circuits rated to 250 kPa, test pressure is typically 300–350 kPa. For surgical instruments rated to 15 kPa, test pressure is 10–20 kPa. Wide pressure range (>500 kPa) favors the Figurtech LY or LG Series; low pressure (<100 kPa) favors the LD Series differential instrument.
2. What is your leak acceptance threshold?
Express this in either kPa pressure decay or SCCM flow rate (preferably both). Thresholds tighter than 1.0 kPa at small volumes (<100 mL) typically require differential pressure measurement. Thresholds expressed in SCCM < 10 require careful calculation: at 40 mL test volume and 100 kPa test pressure, 3 SCCM produces approximately 0.1 kPa decay over 30 seconds.
3. What is the test volume of your component?
Internal volume determines the stabilization time and measurement sensitivity. Small volumes (<50 mL) cool rapidly during charge — requiring longer stabilization or differential measurement. Large volumes (>1 L) have inherent thermal buffering but require longer charge times. Volume estimation from CAD models is typically accurate to ±20%; confirm by fluid fill measurement.
4. What is your required cycle time?
Inline production testing must match the assembly line takt time. Common targets:
- Automotive bearing line: ≤14 seconds (200+ pcs/hr)
- EV cooling tube line: ≤23 seconds
- Medical device validation: 107 seconds (acceptable for Class II device production)
- Consumer electronics IP67: ≤15 seconds per unit (multi-channel for high volume)
5. What are your integration requirements?
Production leak testers must output OK/NG signals and test data to PLCs and MES systems. All Figurtech instrument series support RS-232/485, USB, and Ethernet. PLC I/O (24V digital), barcode scanner input, and MES data upload via Ethernet are standard. For fully unmanned cabinet integration, the Figurtech LE Series embedded module eliminates the need for a front-panel benchtop unit.
Instrument Selection Matrix
| Series | Method | Pressure Range | Best For |
|---|---|---|---|
| LY Series | Direct pressure decay | 0–1200 kPa | EV, automotive, IP67 electronics, high-pressure housings |
| LD Series | Differential pressure | 0–700 kPa | Medical devices, bearings, surgical instruments, low-pressure precision parts |
| LF Series | Mass flow | 0–500 kPa | Capillary tubes, membranes, flow-controlled components |
| LG Series | Auto-regulating direct | 10–1000 kPa | Wide-range, multi-program, large component validation |
| LM Series | Multi-channel (2/4/8ch) | 9.5–150 kPa | Consumer electronics, switch assemblies, high-throughput lines |
| LE Series | Embedded module | 0–1200 kPa | Unmanned cabinet integration, robotic cells, ATEX environments |
Fixture and Connector Selection
The instrument is only half the system. The quick-seal connector and fixture determine whether the test is repeatable and whether false rejects occur at the interface. Key rules:
- Never apply axial force to thin-wall tube ends — use inner-expansion connectors (LT-G01, LT-D01)
- For threaded ports: use hand-screw internal-thread connectors (LT-N01) for repeatable engagement
- For automated lines: pneumatic connectors (LT-Q01/Q02) engage in <0.3 seconds with operator-independent seating force
- Connector pressure rating must exceed test pressure by a minimum 3× safety factor
Validation Before Production
For new applications, Figurtech application engineers will test customer sample parts before finalizing instrument and fixture configuration. This confirms that the proposed test parameters (charge time, stabilize time, measure time, accept window) meet the required false-reject rate and detection reliability targets. Contact us to initiate a pre-production application evaluation.