TL;DR
Vacuum loss during composite cure can cause voids and delamination in the finished part. Check the vacuum bag integrity first, then inspect the vacuum pump and lines if bag is intact.
What you might see
- vacuum level not reaching setpoint before cycle start
- vacuum level drops during hold phase
- vacuum pump runs continuously without reaching setpoint
- post-cure part shows porosity or delamination
Likely causes
Vacuum bag leak at a sealant tape joint or bag penetration
Vacuum line fitting loose or seal failed at the vessel penetration
Vacuum pump oil level low or filter blocked reducing pump capacity
Vacuum valve not fully opening from solenoid or actuator fault
Required tools
- Vacuum gauge (calibrated)
- Sealant tape for bag repair
- Vacuum pump oil (matching pump specification)
- LOTO kit
Safety first
- Never pressurize the autoclave before vacuum bag integrity is verified. A failed bag under pressure causes loss of composite part and potential projectile hazard.
- Vacuum line and fitting work inside the autoclave requires the vessel to be fully depressurized and locked out.
Procedure
- 1
Before placing the load, check the vacuum bag by pulling to setpoint and monitoring the vacuum level for 5 minutes with all valves closed.
- 2
If vacuum holds on the bag alone, the leak is downstream in the autoclave vacuum circuit. If vacuum drops, the bag has a leak.[1]
- 3
For bag leaks, inspect all sealant tape edges and bag penetrations (thermocouple ports, vacuum ports) for bridging or adhesion gaps. Re-seal any suspect area.
- 4
Inspect vacuum line fittings at the vessel penetrations for loose compression fittings or deteriorated O-rings.[1]
- 5
Check the vacuum pump oil level and condition. Milky or low oil indicates a problem requiring pump service.
- 6
Verify the vacuum solenoid valve opens when commanded by checking for the valve actuator movement or using a vacuum gauge on both sides of the valve.
Sources
ASC Process Systems ASC Econoclave Composite Autoclave general technical documentation, ASC Process Systems
ASC Econoclave operator manual, vacuum system inspection and leak testing procedures (general)
More guides for ASC Process Systems ASC Econoclave
How to fix pressure vessel seal leakage on an ASC Econoclave composite autoclave
Autoclave door or penetration seal leakage causes inability to hold cure pressure. Inspect and replace the door seal, check penetration fittings, and verify the seal groove is clean before pressurizing.
How to diagnose temperature uniformity failure on an ASC Econoclave composite autoclave
Temperature non-uniformity during composite cure causes ply delamination or under-cure. Check thermocouple placement, recirculation fan speed, and door seal integrity before adjusting the cure profile.
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