What is Mil Spec MIL-PRF-131 Class 1?

One of the more barrier materials  used in  Mil-Spec  packaging is – MIL-PRF-131 Class 1-  (or MIL-DTL-117 Type 1, Class E, Style 1 when this material is used in BAG form) . It is used when the government needs a moisture sensitive item packaged in a moisture controlled environment.   This is why they call it Barrier Material. It acts as a barrier between the outside air and the part which is sealed inside the barrier bag.

Here is the technical breakdown of this spec.

MIL= Military. Next is PRF.  PRF is short for performance.   What this means is that all materials used  to meet this spec must have the same  level of performance .  They then add a numerical ‘code’  ( IE: 131-  or 121- or 81705 ) to differentiate and identify the different kinds barrier materials.  Each has it’s own properties. The 131 number is a  water vapor proof,  foil based  flexible packaging material.  That leaves us with  the Classes.  There are 3 classes.  Class 1, Class 2, and Class 3)  Each one has it’s own characteristics.   Each of these classes calls out for a specific ( different ) laminated  material. IE: Class I is always a Film (usually Nylon or PET) Foil laminate  , Class II is always a Kraft ( paper) foil laminate and  Class III  is always a scrim ( cloth) foil laminate ,  These materials  are printed with the pertinent MIL-SPEC numbers and  can only  use materials that  are listed  on the governments QPL . (Q)ualified (P)roducts (L)ist.

All MILPRF 131 Type I , Class I materials will look and perform the same as each other.

How is this purchased?  First you can buy the raw material in 36” or 48” size rolls.  This way you can roll some material out, make your own bags with a heat sealer,   We also make bags in house any size or quantity you need.  We can make also provide tubing which is like  a  100yard long open ended bag on a roll that is sealed on both sides . Just cut  off the length you need and heat seal the top and bottom  to make a bag. We can even make 5 sided (3-d bags) for your really tough to fit items. Just call us and we can give you all the information you need.