Envelope bags are used to process a variety of small to mid-sized parts in autoclaves, ovens, and at room temperature. They're ideal for laminates or assemblies that require even pressure from all sides. Envelope bags can be configured with one, two, or 3 sides that open, and are available with vacuum ports and thermocouple pass-throughs.

A typical envelope bag that opens on one side. On the right is our VP36 1/4" male npt vacuum port with a QD11 quick-disconnect installed. On the left is a type J thermocouple pass-through that accepts a standard tc plug on the inside and outside of the diaphragm.

Torr can also provide our elastomeric vacuum tools, including envelope bags, with translucent, high-strength silicone diaphragms.

This 3-side opening envelope bag includes (2) vacuum ports and (3) type J thermocouple pass-throughs. Type K is also available.

Although not visible in this image, the lower diaphragm of this 3-side opening bag is made of our Interflow™ breather-pattern high-strength silicone. It conforms to the underside of the mold and provides a means of removing gases. The increased thickness of the Interflow makes the envelope bag less likely to be punctured during transport.