Fits Like a Glove: Buying the Right Size Heat Shrink Tubing

May 15, 2018 by  
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Imagine if buying a heat shrink tubing was as simple as buying a coat. You measure the object you want to cover and then buy a heat shrink to fit.

Unfortunately, it’s not.

Buying a right size heat shrink is much more complex than buying a right size coat. Because the tubing shrinks, when heated, does not retain the same dimensions it originally has pre-heating.

As such, it’s common for buyers (especially, first time buyers) to make sizing mistakes when buying a heat shrink tubing, ending up with a purchase that just won’t fit into their application.

This piece will guide you on how to avoid sizing mistakes and buy a right sized heat shrink tubing for your application.

First things first…

Before we get into the nitty gritty of how to measure a heat shrink when purchasing one, it’s worth noting that heat shrink tubing is first made to the diameter it will be when it’s shrunk. After that, it is expanded and packaged for sale.

So when you buy a heat shrink tubing, its shrunk dimensions are already known; they’re stated on the specification sheet.

Having this explained, we can now move on to the actual measuring step.

Dimensions and Dimension Facts—You Should Know About!

When measuring a heat shrink tubing, there’re basically two types of dimensions you’ll be working with: i) Recovered dimensions and, ii) Expanded dimensions.

Recovered dimensions are the shrunken dimensions and expanded dimensions are the dimensions of the tubing in the stretched form.

On a typical heat shrink datasheet, you’ll find the following dimensions listed:

  • Recovered internal diameter
  • Recovered wall thickness
  • Expanded internal diameter

Let’s say you want to buy a heat shrink to cover a cable which has an outer diameter of 7 mm.

The heat shrink that you buy must have:

  • An expanded internal diameter greater than 7 mm
  • A recovered internal diameter of just under 7 mm

Please note that you won’t find the exact dimensions listed on a heat shrink tubing’s datasheet. They will always have some tolerance range which will be mentioned on the sheet. So make sure you keep that in mind.

What about the wall thickness?

It depends on the application in which you want to use the heat shrink. If wall thickness is really important for your application (for e.g. If you’re looking to insulate a piece of wire), we would recommend that you purchase a heat shrink tubing with the maximum recovered wall thickness.

Let’s take a look at another example.

Let’s say you want to buy a heat shrink tubing to insulate a cable wiring. The cable has a diameter of 7 mm. It has bare wires running through it which are 4 mm in diameter. Plus, the cable has a connector at each of its end, which has a diameter of 15 mm.

The heat shrink that you buy must have:

  • An expanded internal diameter greater than 15 mm
  • A recovered internal diameter of just under 4 mm

For wall thickness the rule is same as discussed above.

One more thing you should keep in mind…

A heat shrink tubing not only shrinks in diameter when heated, but it also shrinks in length. Although the change in length is minimal, usually 10% of the original expanded length. So if you need a heat shrink tubing to cover an object of length 2 meters, you should buy a heat shrink which is at least 2.2 meters long. You can later cut off the tailing end if you wish to.

And that is how you can buy the right size shrink tubing for your application that will fit like a glove.

A BONUS read: The Chemistry Behind the Working of Heat Shrink

All You Need To Know About Heat Shrinkable Probe Covers

October 30, 2017 by  
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Regardless of whether you are an engineer or an electrician, you must already be familiar with the term “heat shrink tubing” and ” Probe Covers “. In fact, there is also a high possibility that you’ve come in contact with them and know how they work.

Initially, heat shrinkable tubes were used to safeguard electrical wires only. But, over time, their efficacy extended to a wide spectrum of industrial and commercial applications. A number of industries now rely on PFA tubing to prevent fire and lessen energy dissipation, and in the process, cut their manufacturing costs.

Read on if you are interested in getting to know more about the benefits of heat shrink tubing.

1.      They can resist high temperatures.

Heat shrink tubes can withstand extreme temperatures and hence, can work under harsh chemical conditions which can melt other lesser materials. With a melting point as high 320°C and a freezing point as low as –268.15°C, these tubes are able towithstandall freezing cold and blistering hot chemical environments.

2.      They can withstand abrasion.

Fortunately, heat shrink tubes are added to industrial products so as to enhance their resistance to accidental damages and physical abuse.

3.      Their end caps protect the product.

Assuming that you are connected to the field of science in one way or another, it’s understood that cutting a wire to resize or rework its shape according to the “electrical need” is something you’ve done time and time again.

This goes without saying that if you fail to insulate the wire properly, the cut can cause trouble.

Thankfully, with encapsulating heat shrink tubes, you need no longer worry about overheating or shorting of circuits. Considering safety is your topmost priority, heat shrink tubing offers high performance with utmost protection.

 

Heat Shrinkable FEP & PFA Probe Covers

Probe covers serve as an end cap plug for the expensive glass or metallic probes used in high-temperature or corrosive processes.

Since these parts are placed in hard-to-access positions in a circuit, and reside in a gas or liquid stream, encapsulating them with heat-shrinkable FEP or PFA covers increases their longevity.

This is mainly because of the chemical inertness and excellent lubricating, and high electrical and thermal resistance properties that these fluoropolymer tubes have to offer.

The FEP and PFA probe covers engineered at Tef-Cap Industries act as protective shields  for a number of industrial products such as probes, thermocouples, resistance temperature detectors (RTDs), thermometers and assorted sensors. In corrosive environments, these probe covers create an impenetrable barrier between the caustic chemicals and expensive sensing devices.

 

Interested in getting your instruments encapsulated by Tef-Cap’s heat shrinkable probe covers? Get in touch with us now: 610-692-2576.