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B.I.R.S. Machine & Supply is a distributor of FEP Heat Shrink Tubing.


FEP (fluorinated ethylene propylene) heat shrink tubing is chosen particularly for its lower

shrink temperature than other heath shrinks such as PTFE. FEP also has greater flexibility, optical clarity, and high lubricity in comparison to PFA. In addition to those traits, FEP heat shrink is commonly chosen for its lower cost and for applications where large heat shrink ratios are not needed.


FEP heat shrink tubing products are provided in their expanded state. With the brief application of heat, they mold themselves snugly around the most intricate and irregular shapes to form a completely sealed covering. Sources of heat and methods of heating are optional.


Shrink Ratios and Recovery

Heat shrink ratio refers to the final diameter of the heat shrinkable material after being allowed to shrink fully unrestrained compared to the original diameter of the pre-shrunk material. After heat shrinking is complete, the material is considered to be in its “recovered” or “recovery” state. Thus, final dimensions for heat shrink usually refer to recovered or fully shrunk dimensions.


As an example, for a heat shrinkable material with a 3:1 heat shrink ratio, the final diameter of the fully shrunk material will be reduced to 1/3 of the pre-shrunk diameter.  Or, put another way, the original diameter of the pre-shrunk material will be 3× the diameter of the fully shrunk (recovered) material; the ratio of their diameters, pre-shrunk or recovered state, will be 3:1.


Note: that heat shrink is typically applied over a material or component to encapsulate it; thus, in practical application, it is restrained from being shrunk completely.


Heat shrink ratio is a fundamental consideration for every application based on the degree of non-uniformity of the items or components to be covered. More irregularly shaped parts will require greater heat shrink ratios of the covering material to achieve more complete or thorough encapsulation. Conversely, more uniform parts such as cylinders or wires would require smaller heat shrink ratios for complete coverage. Consideration should also be given to tapered parts: While appearing to be more or less uniform in shape, the degree of taper should be taken into account when selecting heat shrink and its shrink ratio.

FEP heat shrink tubing is available with 1.3:1 and 1.6:1 or greater shrink ratios and can be selected based on American Wire Gauge (AWG) or fractional sizes. This heat shrinkable material possesses all of the same high standards and characteristics of FEP. We can also provide custom micro-miniature dimensions and other tailored specifications and tolerances upon request.


Heat Shrinking Guidelines for FEP Heat Shrink Tubing

  • Always assure good ventilation in the immediate work area before beginning the heat shrink process. (Caution: Fumes can cause nausea and dizziness).

  • FEP heat shrink tubing requires approximately 420 °F ± 50 °F (215 °C ± 10 °C) to initiate shrinkage. This is a liberal and safe range. Please note that these temperatures are approximate. Actual shrink temperatures may vary based on the dimensions and wall thickness of the tubing, methods of application, and other factors. We are happy to provide samples to test in your application to determine the best material to use.

  • The mandrel (part) to be covered by FEP heat shrink must be able to withstand the heat shrink temperature range.

  • Parts or mandrels may act as a heat sink, which may cool the heat shrink prematurely. Therefore, Zeus recommends preheating larger diameter mandrels and other parts.

  • FEP heat shrink needs only a small amount of recovery. Some slight longitudinal change is normal and may vary depending on the extent of recovery.

  • Heating and cooling should be even on all sides for best results. Uneven heating or cooling tends to split the side of the heat shrink which is still in the "gel" state with the other side in the hard or crystalline state, particularly upon recovery.

  • NOTE: Shrinking starts when the FEP is brought up to the "gel" state but completes its recovery during the cooling cycle. In its gel state the tubing becomes crystal clear with a glassy appearance.

  • Ovens are the most reliable way to recover heat shrink products due because of their ability to ensure even heating and reduce the risk of overheating the material (which can lead to brittleness and cracking). 


Applicable Specifications

FEP Heat Shrink complies with AMS 23053/11 Class 2.

For all cases of military or commercial specifications, latest revisions apply. Our FEP heat shrink is supplied in natural color unless otherwise specified.  Mil-STD-104 colors are available upon request.



  • Encapsulation – For general purpose protection and covering of critical components, FEP heat shrink may be the best choice for your application regarding cost, heat shrink temperatures, and other features which are comparable to more expensive products. FEP 1.6:1 heat shrink provides slightly more shrinkage capacity than our FEP 1.3:1 heat shrink offering coverage of a broader range of component shapes. FEP heat shrink is routinely used to cover such items as medical instruments, temperature probes, roll covers, lighting, hoses, wires and cables, to name but a few. FEP heat shrink’s transparency allows your covered components to remain observable during use while remaining protected from heat, chemicals, moisture, and temperatures.


  • Insulation – FEP’s dielectric properties make is a good choice for encapsulating and insulating electrical components including batteries (lithium and alkaline) and solenoids. FEP heat shrink’s heat tolerance allows it to continue to perform at temperatures commonly encountered in electrical environments.


  • Wire Harness – FEP heat shrink’s excellent dielectric properties make is a good choice for covering wires and cables and can even support splicing. Once covered, FEP heat shrink also serves as insulation.



  • Biocompatible – FEP heat shrink is non-toxic and USP Class VI approved, so you can trust that it meets your biocompatibility needs.

  • Chemically Resistant – FEP heat shrink is impervious to nearly all common solvents whether they are acids, bases, or hydrocarbons.

  • Excellent Dielectric Strength – FEP heat shrink possesses exceptional dielectric strength and thus doubles as insulation when used with electrical components.

  • Excellent UV Transmission Ratings – This product’s UV ratings mean that it can stand up to extended UV exposure and not degrade or breakdown. The ability of our FEP heat shrink to withstand this type of UV exposure means that it can be used under sterilizing UV light and outdoors.

  • Flame Resistant – The non-flammable nature of FEP makes it a good choice for environments where there is high heat or the possibility of flame exposure. FEP heat shrink is UL 94 V-0 rated.

  • Low Absorption of Solvents – Consistent with FEP’s negligent chemical activity, FEP heat shrink has extremely low absorption of solvents.

  • Many Preferred Traits over PTFE – FEP heat shrink has a lower gas and vapor permeability than PTFE and is less expensive; FEP is also more flexible than PTFE and possesses greater optical clarity.

  • More Lubricious than PFA – FEP has a lower coefficient of friction than PFA giving it a highly lubricious surface.

  • Optical Clarity – The transparency of FEP heat shrink assures that your covered parts remain visible yet protected; this allows you to monitor the integrity of covered parts or wire splices.

  • Sterilizable – FEP’s temperature tolerance and physical properties allow it to easily tolerate gamma, ETO, e-beam, and autoclave sterilization protocols.


B.I.R.S. Machine & Supply

12 Buckelew Bridge Road

Anniston, Alabama 36207

P: (256) 405-5370

F: (256) 831-9057



We are located in east Alabama just off interstate I20 between Atlanta, Georgia and Birmingham, Alabama.


We supply other high-performance heat shrink tubing in a variety of polymer resins including PTFE, FEP, PFA, ETFE, PET, PEEK; and PTFE / FEP Dual-Shrink®.


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