Frequently Asked Questions

Faqs

Select Category
  •  
GeneralFAQs
What does the term "maximum recovered I.D." mean?

This refers to the final inner diameter of the tubing after the tubing has been fully shrunk, or recovered, through the careful application of heat. A maximum value is specified to ensure that the tubing will fit snuggly about the object being covered. In the case of a tubing that is supplied as ½-inch minimum supplied I.D. tubing, with a 2:1 shrink ration, the recovered I.D. will always be 0.250-inches. While this tubing may "recover" to fit a 0.240-inch item snuggly, it will always recover to provide a snug fit to an object 0.250-inches.

What does the term "minimum supplied diameter" mean?

This refers to the inside diameter, or I.D., of the tubing as supplied by the manufacturer. Typically it reflects a minimum value so that the tubing will readily slide over the object to be covered. In the case of tubing that is supplied as a ½-inch, minimum supplied I.D. and a 2:1 recovery (this means it shrinks to about one-half of its supplied size), the supplied tubing is always supplied with a minimum I.D. of 0.500-inches.

What happens to the tubing wall thickness when the tubing is recovered?

After recovery, the tubing wall thickness increase to some extent. Because of some variability, the recovered wall thickness is generally specified as a nominal value.

What is the best way to recover FIT® Heat Shrinkable Tubing?

This is very important since many people appear to get into "trouble" when they attempt to recover heat shrinkable tubing. There are several methods to recover heat shrinkable tubing, from an open flame, low velocity torch, or high heat light sources to precision hot air sources to the most common, the standard heat gun. If done properly, any of these sources will result in good tubing recovery; done improperly, each will provide poor recovery at best and tubing/substrate damage at worst. We will review the recovery technique through a review of two typical examples. Example A: Assume that we must make a repair to the black PVC covering on a 3-ft. metal tube with an OD of about 1-inch. The breach in the tube's PVC cover in at the midsection of the tube and is about 4-inches in length. First let's assemble the tools required . . . Since we wish to repair the breach with a similar material we will select an Alpha Wire FIT®-105, black, PVC based, FIT® Heat Shrinkable Tubing. Since the tube OD is about 1-inch and this tubing has a 2:1 shrink ratio (it recovers to 50% of it's original, supplied size) we may use an Alpha Wire FIT®-105-2, or a 2-inch, supplied ID product. If we would like a somewhat tighter fit, we would recommend an Alpha Wire FIT®-105-1-1/2 that will recover to a ¾-inch diameter. Since the breach is about 4-inches and we wish to overlap the area plus account for some longitudinal shrinkage, we will require about 6-7-inches of the Alpha Wire FIT®-105 Heat Shrinkable Tubing. The Alpha Wire FIT®-105 Heat Shrinkable Tubing recovers at a low temperature, about 100°C so an Alpha Wire FIT® Gun-3 will suffice (temperature: 400°C - 585°C). The performance of this gun is more than adequate for the job. Now to the actual restoration (or repair) . . . Carefully trim away any loose sections of the original covering so that a neat section of exposed tubing is visually apparent and the remaining covering is close fitting to the tube. Slide the length of repair Alpha Wire FIT®-105 over the breach, centering over the breach (the tubing should cover the entire void plus provide overlap to each end of the remaining tube covering. With the heat gun at temperature carefully heat the tubing at the MIDSECTION keeping the heat gun constantly moving about the tube perimeter. If you stop, or dwell too long, you will DAMAGE the tubing. As the tubing begins to recover, continue to heat about the perimeter, working your way towards the tubing end. Once complete (recovered), begin to recover the remaining half of the restoration tubing, starting at the center, traversing about the perimeter and out towards the restoration tubing edge. Once complete, the restoration tubing will fit tightly about the tubing (you may see a ridge where the underlying covering and tubing meet) and there will be neither gaps nor burnt sections. Example B: Assume that we must protect a section of bare copper wire that passes through a very caustic environment. The wire section to be protected is 18-inches in length and each end of the wire exits outside the area of caustic chemical. The wire to be protected is a 10 AWG. First let's assemble the tools required . . . Since we have a very harsh environment, we choose to protect the wire with a FIT® Heat Shrinkable Tubing made of TFE Teflon™, a material resistant to almost every known chemical at room temperature. Since the wire to be protected is a #10 AWG, we may use an Alpha Wire FIT®-500-10 with a shrink ration of about 1.5:1. Since we are required to protect a wire some 18-inches in length, we will use a standard 24-inch length of Alpha Wire FIT®-500 product. We will use the entire 24-inch length since we don't know the specifics of how the tube passes through the vessel wall that house the caustic chemical. The Alpha Wire FIT®-105 Heat Shrinkable Tubing recovers at a low temperature, about 100°C so an Alpha Wire FIT® Gun-3 will suffice (temperature: 400°C - 585°C). The performance of this gun is more than adequate for the job! Now to the actual restoration (or repair) . . . Place the length of Alpha Wire FIT®-500 over the wire. Since the wire to be covered is relatively small, the reflector will be fitted to the heat gun (this reflector allows the entire perimeter of the wire and tubing to be heated without need to keep the gun in motion about the wire perimeter.) With the heat gun at temperature carefully heat the tubing and wire at the MIDSECTION keeping the heat gun moving from the center to one end of the applied Alpha Wire FIT®-500 Heat Shrinkable Tubing. Once recovered, start at the center section again, and recover the remaining half of the tubing moving towards the other end of the wire and tubing. In this case, if you stop, or dwell too long, you will not damage either the tubing or the wire since both are very resilient to heat. There you have it, two examples of FIT® Heat Shrinkable Tubing recovery without damage.

How do I know what is the best FIT® Heat Shrinkable Tubing material to select for my application?

First, think about how you wish to use FIT® Heat Shrinkable Tubing . . . is it for: Bonding Breakouts Bundling Color coding Encapsulation Environmental protection - direct burial Environmental protection - immersion Environmental protection - splashing Fixturing Holding Identification Mechanical protection Special properties (fire protection, conductivity, LSOH applications) Strain relief The Alpha Wire Master Catalog provides information as to what materials are best suited for these types, as well as other, applications. Next, determine if your operating environment is varied, i.e., Hot and cold temperatures Assorted chemical exposure Combined mechanical abuse . . . abrasion and flexing, vibration and impact, etc. Fire situations Ultraviolet and ozone exposure EMI and RFI exposure Again, the Alpha Wire Master Catalog provides an extensive list of properties for the different tubing types and materials. Once the application and environmental conditions are understood, then the proper tubing material may be selected.

What size FIT® Heat Shrinkable Tubing should I use for my application?

The basic answer is that it depends upon the specific application. A practical approach to determining the size of tubing to use is simply to use one that will shrink to about 70% of the minimum supplied I.D. For example, to cover a cylinder of diameter ¾-inch, a tubing with a minimum supplied diameter of 1-inch should be used. To cover a ½-inch bar, a ¾-inch tube should be used. Now, for this latter case a 2:1 shrink ratio tubing could be used if one wished to maximize the recovered wall thickness.

AlphaWire