No doubt that many of you have read in manufacturers brochures things such as plain weaves, straight weaves, twill, basket, bias or even circular weaves. This does sound confusing but when you break it down it is actually quite simple.

First of all, all fire hoses are circular woven with the exception of the 5/8” and 3/4” (16 and 19 mm) forestry hose that is woven flat on a needle loom. Circular woven simply means that the jacket is woven in a continuous circular fashion and therefore has no seam. This yields a smooth fabric with no bound seam to weaken its structure.

The other types of weave are just variations of the same circular weave and are used to produce hoses with different performance qualities. For instance we can vary the weave if we want to have a more flexible or more abrasion resistant hose. If we require a smoother bore, this can also be achieved. Like everything else, however, achieving the optimal property is usually done at the expense of another. For this reason, hose is designed to give the desired performance characteristics by compromising different parameters to arrive at a finished product that will satisfy the users needs.

Lets look at the types of weave, there are two main variations: the plain or straight (sometimes basket) and the twill or bias. The plain weave is exactly what it says it is. It is woven in a square fashion with the filler or weft yarn at right angles to the warp yarn. Depending on how tightly the fabric is woven, this gives a jacket of medium smoothness and a lot stiffer than equivalent woven twill weave.

A plain weave usually is used because less material is required to produce a firm and stable jacket. In this type of jacket, 50% of the warp yarn covers the jacket on the outside and 50 % covers the inside. It is this warp yarn which covers and protects the filler yarn which gives the hose most of its structural integrity. Once the warp yarn is worn and the filler exposed, the hose is doomed.

Another factor, important to the weave and of course the performance of the hose, is the picks per inch (the number of times the filler passes across the jacket in a one inch length). The higher the picks per inch, the stiffer the jacket. If the jacket is tighter and stiffer, it is also less prone to puncturing or snagging. High pick counts are slower to weave though and this is why some manufacturers weave with low picks. A 7 1/2-pick jacket weaves twice as fast as a 15 pick jacket.

The twill weave is the most fun of all and it is here where a designer can be a little more creative. Primarily twill is used when more abrasion resistance is required. This is achieved because unlike the plain weave, the twill puts 66% of the warp yarn on the outside of the jacket; this is 16% more than the plain weave.

The other main advantage to the twill is that for a given amount of yarn, it is much more flexible than the plain weave. This is because the warp yarn does not pass over and under every filler yarn as it does in the plain weave. Instead the warp passes under one filler and then over two. Because of the decreased interaction between the warp and filler, the jacket is less stiff. Normally, more warp yarn and higher picks are required to yield a comparably stiff jacket to the plain woven one. Because of the extra materials, the jacket is more rugged. If you look at the twill weave, you notice a diagonal pattern in the warp yarn. This is only an illusion. The jacket is woven square as is the plain one, but the shifting pattern with each rotation of the loom gives the impression of a diagonally woven fabric. To produce a variety of other effects, such as smooth bore or less twist, the twill weave can also be altered in other ways.

As you can see the hose designer has a number of ways in which he can produce a desired finished product. Juggling and compromising the different parameters can achieve almost anything.