Delivery hoses - Page 3

How to choose a delivery hose?

Because there are so many varieties of delivery hoses, choosing the right one can sometimes be difficult. Therefore, if you need help in making a decision, pay particular attention to the following points:

• Friction resistance,
• Type of medium,
• Environmental factors,
• Standards.
  

Friction resistance

No discharge hose can completely avoid the abrasion damage that results from the transport of solid materials.

What is abrasion? This term is used to describe the process of scraping or abrading the inner layer of the hose. It most often occurs in hoses that are characterised by a rough inner wall.

Therefore, PU hoses are best suited for the transport of solid media. This material is distinguished by its low coefficient of friction, making it well suited to the transfer of gravel, sand, cement, etc.

PU hoses are generally more abrasion resistant than standard PVC hoses.

Type of medium

Always select the delivery hose to suit the medium it will be transporting. Transporting substances for which the hose is not suited will lead to deterioration in quality.

For example: a water hose will not transport petrol efficiently. Not only will it wear out more quickly, but it also poses the risk of fuel contamination as a result of leaching from the inner wall of the hose.

Environmental factors

When you are choosing discharge hoses, also pay attention to the environmental factors that are present in your area. These include issues such as exposure to sunlight, extreme temperatures or dragging on the ground.

Generally, hoses lose elasticity at low temperatures, which can cause rupture. In contrast, at high temperatures, hoses can deteriorate (e.g. melt).

Furthermore, exposure to UV radiation (sunlight) leads to chemical degradation of some materials in a process known as UV degradation.  It is therefore useful to know whether a hose is resistant to this.

The local environment also plays a role. Chemical hoses working in chemical plants degrade faster than their counterparts used in agriculture.

Standards

Last but not least are the standards for the various industries. Check that the hose meets them. This counts especially for hoses that come into contact with food products or chemicals.

For these types of hoses, the European Union and the United States have developed a special set of standards that ensure the safety of workers and consumers.

How is a discharge hose designed?

The construction of a discharge hose largely depends on its intended use. However, in most cases, the hoses available on the market consist of three layers:

• inner (adapted to the specific medium to be transported);
• reinforcement (usually a textile, synthetic, or steel braid, which provides the hose with the strength to withstand the working pressure); 
• outer (created to cope with environmental conditions).

There is also a suction and pressure hose that has special spiral reinforcement (steel or plastic). As the name suggests, it is not only suitable for pumping (operation under positive pressure), but also for suctioning the medium (operation under vacuum). The reinforcement prevents the hose from collapsing inwards.

Finally, it is worth mentioning flat discharge hoses, which are most often made of soft plastic and are mainly used for pumping water or wastewater.