Reasons to Leak Test
1. Product Safety & Liability
• Medical components may cause injury or death when leaking during or after procedures (heart catheters, IV sets, etc…).
• Automotive components may cause injury or death when leaking in operation (flammables and brake related components).
• Appliances may cause electrocution of the user (irons & steamers).
2. Quality Control
• Most common method of testing bonded plastic components which require hermetic joints.
• Testing parts following assembly can alert maintenance to setup problems with welding equipment.
• 100% testing virtually eliminates field failures related to the bonding/joining process.
Leaks are detected visibly or by measured decay by specialized fluid pressure gauges or electronic sensors.
• Simulates "real-world" conditions for parts designed to contain or pass fluid.
• Performs superbly for testing at pressures above 500PSI.
• Preferred for destructive testing (pressurize to burst).
• Added Costs: Parts often require cleaning/drying after test.
• Time Consuming: The time required for fluid to leak through a small void in the part can be considerable, sometimes hours.
• Messy: Fluid gets everywhere when testing using this method.
• Costly Equipment: Equipment for fluid testing is often custom made per application and must consider containing fluid.
Leaks are detected visibly when immersed in fluid, or audibly when using sensitive "listening" devices or by electronic sensors when using pressure-decay instruments.
• Fast: As air molecules are roughly 500X smaller than water molecules. Can detect much smaller voids in parts in considerably less time than fluid testing.
• Low Cost: Sensitive equipment is available by many manufacturers at far lower costs than sensitive fluid systems.
• Clean: Parts do not have to be cleaned of fluids after test.
• Very costly to achieve pressures above 500PSI.
• As air compresses so much more than fluid, can be difficult to use for some destructive tests.
• Only represents (does not duplicate) "real-world" testing for parts containing or passing fluid.
Leaks are detected visibly when immersed in fluid (liquid entry into part) or by specialized electronic vacuum sensors or gauges with vacuum-decay instruments.
• Ideal for parts that will have internal vacuum applied.
• Can create leak paths that cannot be replicated by pressure testing such as dynamic seals ("o" rings and rubber diaphragm valves).
• Not good for testing parts that would otherwise have pressure applied internally in actual application as the vacuum may inadvertently seal small voids in flexible parts.
• Vacuum is limited to approximately -14.7 PSI (ideal vacuum). With typical vacuum pumps, only -10 PSI or so may be possible.