A Guide to Bend Radius For Hoses

The Hosemaster

June 12, 2024

Although hoses seem like very simple objects with a very basic function, it’s actually super important to make sure you’re using the right type of hose for the machine or application you’re dealing with.

That’s because there are more variable factors to hoses than you might have first thought – and it’s essential that you figure out the exact shape, material, length, thickness, flexibility, diameter of hose you need. One variable factor that is often overlooked, but is actually pretty critical for function and safety, is the bend radius of a hose.

Here, we’ll get you up to speed with what a bend radius is, why it’s so key to get right, and how to measure and calculate the bend radius of any hose.

What is a bend radius?

So first off, what is a bend radius?

This term is used to describe how long a hose needs to be in order to bend, flex, and move safely within a space without being damaged in application and operation. The bend radius also provides key information about the minimum distance a hose can be bent without malfunctioning or sustaining damage.

What can impact hose bend radius?

There are actually a variety of features that will affect the bend radius of your hose, including:

Hose diameter: how thick or thin a hose is (i.e. its diameter) will normally influence its bend radius. Hoses with a larger diameter tend to have a larger bend radius and vice versa because there is more material that needs to curve.
Hose construction: different types of hoses are made in different ways, which impacts bend radius. A hydraulic hose, for example, is normally made using three layers: a core, a reinforcement later, and a cover. The reinforcement layer alone can be 1-2 layers of thick textile or steel, or even 4+ layers if wound steel is used. As a result, a hydraulic hose will be able to bend far less readily than a thinner, single, or double-layer hose with less bulk.

An image of a hydraulic hose connector

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Hose material: hoses are made from a whole host of different materials. Vacuum hoses are often made from PVC, for instance, while radiator hoses are often made using rubber or silicone. What a hose is made from will impact its bend radius. Rubber, for example, is far more willing to bend and therefore offers a smaller (tighter) bend radius than a harder material like metal or reinforced PET.

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Location and usage: the conditions a hose is being used in can also have an effect on bend radius. Environmental factors like temperature and pressure can cause changes in the material the hose is made from and therefore impact how much it is able to bend without causing damage.

Bend radius vs hose flexibility

Bend radius and flexibility are related and certainly similar but they’re not quite the same and it’s an important difference to be aware of. As we explained above, bend radius describes how long a hose needs to be in order for it to bend without damage. Flexibility, on the other hand, incorporates other factors like force to bend.

For example, a 2” rubber hose has a bend radius of 6”, while a composite hose of the same length has a bend radius of 3.5”. Already, the bend radius is very different – and this hasn’t taken force into account. The composite hose not only has a smaller bend radius, but also requires around 75% less effort to bend it into shape, which makes it far more flexible than the rubber hose.

Why does a hose bend radius matter?

The nature of a hose, in any application, means that it will need to bend and flex when it’s in use to ensure that everything can run smoothly and maintain proper functionality and safety. Therefore, knowing the appropriate bend radius of a hose is a crucial part of making sure a hose will be strong and flexible enough for the task at hand.

By adhering to the correct bend radius of your hoses, and using them appropriately, you can:

Ensure the hose won’t be bent beyond its limits, as doing so will cause stress points along the hose pipe – causing it to malfunction, clog, perforate, or tear. Overbending will also lead to increased pressure dropping which can affect the functionality of your machinery.
Extend the lifespan of your hose and the machine or application it’s working within – using the correct hose in the right position will help to prevent long-term damage.
Prevent kinking and distortion along the hose pipe, which, again, leads to malfunction and damage.
Improve the health and safety rating of your system. A hose that can’t bend or flex correctly is one that can pose a serious safety risk. For example, if a hose tears or bursts around electrical wiring, this can lead to serious damage, injury, or even fatalities.

Adhering to the correct bend radius for a hose is particularly critical in tight spaces and/or where the hose will be required to bend around sharp corners, or when using machines or cylinders that will require the hose to extend or retract.

How to calculate bend radius

So, now that you know how important bend radius is, how do you calculate it?

Essentially, bend radius is measured as the distance to the inside edge of the hose when it forms a 90-degree bend – this is called the ‘inside radius’ (as opposed to the centre of the hose, called the ‘centreline radius’). The great news is that normally, you’ll be able to find the specific bend radius of a hose in the manufacturer’s guidelines or product specifications.

This will then help you to find out how the minimum length of hose you need, using the following formula:

L = A/360° x 2????r

Within this equation, L stands for the minimum length a hose needs to be in order to bend safely without damage. A is the angle you need the hose to bend, whilst r is the bend radius of the hose. Finally, ???? (pi) is usually given at 3.14.

So, let’s look at an example and fill in the gaps. Say you need a hose that can bend at a 65° angle, with a bend radius of 3.5”.

65°/360° x 2(3.14 x 3.5) = 3.97 – so your hose will need to be at least 3.97 inches in length.

Another unit you may be given by the manufacturer is the bend factor. If you know the bend factor of a hose, you can figure out the bend radius. For example, if you have a hose with a diameter of 2” and the manufacturer specifies a bend factor of 6, you can do 2 x 6 to get 12. This means the bend radius required for this hose is 12”.

How to protect your hose during use

Using hoses appropriately isn’t limited to checking their bend radius – there are several things you can do to protect your hoses during use.

1. Avoid sharp corners where possible

Where possible, avoid the hose having to bend around and rub against sharp corners. Try to position the hose around a gradual curvature instead to avoid abrasions that could cut into your hose and pose a safety risk.

2. Use clamps for added support

Use purpose-built clamps to hold the hose in place at various points to prevent excessive movement and overbending. Clamping will also stop the hose from getting caught on anything and becoming damaged as a result of snagging.

An image of a silver clamp

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3. Consider installation carefully

When installing a hose, don’t be tempted to coil and cram it into a space that’s too tight. This will force the hose to overbend and inevitably lead to kinks, holes, and other long-term damage. This is particularly important in machines or applications that require the hose to move, retract, or expand – as this type of hose needs freedom to move or it will be restricted and unable to perform as it should.

Explore our extensive range of hose and ducting at The Hosemaster

From hoses, tubes, and pipes to flexible tubing designed for air, garden, plumbing, hydraulic, pressure, and vacuum use, at The Hosemaster, we’ve got you covered. Explore everything from suction and sanitation to food and fire, as we stock a wide range of hose and ducting products for almost any application.

You should be able to find everything you need on the website but if you have any questions, please don’t hesitate to get in touch for further guidance. Our team is always on hand to help you throughout your buying journey.