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Selection criteria
Just as there are differences between materials used in hoses, so are there differences between hoses using the same base material, like Teflon. Here are some of the basic characteristics to consider in choosing a hose for a specific application.

1.Smooth or convoluted bore? 

The primary differences are size and bend radius. Smooth bores are generally available only in bore sizes of 1 in. or less. For that size, a smooth bore hose has a minimum bend radius of 12 in., whereas a convoluted bore hose has a 3-in. minimum bend radius.

2.Wall thickness? 

Thicker walls are better for applications where the hose is flexed severely, as they are more resistant to buckling. Thick wall hoses are also less permeable to gasses. Thin wall hoses tend to cost less, because they contain less material.

3.Braid material? 

Type 304 stainless steel is the baseline braid material for most Teflon hoses. Type 316 stainless is recommended for marine hose applications. Braid material also plays into pressure rating of a hose. Some materials and hoses can handle pressures to 5,000 psi. Monel and bronze-braided hoses typically have lower pressure ratings.

4.Fittings?

 Teflon hoses are suitable for use with crimp, swage, or reusable fittings. Use the type you prefer, as there are no significant performance differences.

5.Interior or exterior? 

Hoses exposed to severe environmental conditions can be fitted with several forms of external protection, such as extruded thermoplastic and silicone sleeves, fire-resistant sleeves, and various types of metallic protective enclosures. Hoses used in vacuum can be fitted with internal coils or sleeves to prevent collapse.

Three common mistakes
To avoid application errors in your designs, beware of these common misunderstandings or “myths” about hoses made of Teflon

1.Teflon hoses are a high-cost item: 

While it is true that the Teflon PTFE paste used to make high grade hose is a premium material, the hose itself is often a more economical choice than traditional products when total lifecycle cost is considered. There are a number of factors to consider when comparing hose cost and performance.

Hoses made with Teflon can also reduce warranty costs for products like commercial/industrial coffee machines that tend to receive little or no maintenance from end users. They also add a factor of safety when used to drain hot products like fryer grease in fast food restaurants.

2. Teflon hoses tend to kink and crush easily: 

The truth is that all hoses tend to kink and crush easily, especially when they are improperly applied. Hoses made with Teflon are no better or worse than other materials when recommended bend radii and loadings are adhered to.

In applications where kinking or crushing is a possibility, it is a simple matter to add internal or external spring guards to reinforce the hose at critical points. Selecting a hose with thicker walls and a convoluted bore will also minimize kinking and resist crushing.

3. All hoses made with Teflon are the same:

Teflon is a trade name that is applied to a whole family of fluoropolymer-based materials, not all of which have the same properties. Two different Teflon materials are typically used in the hose industry, a melt-extrudable form (such as PFA, FEP, or ETFE) and a paste-extrudable form (PTFE).

Melt-extrudable materials necessarily have a lower melting point than paste-extrudable materials. The also exhibit lower flex fatigue resistance.