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Key points of this article
- The soft PVC resin used for hoses contains plasticizers, which help hoses maintain their flexibility.
- Hoses harden due to the evaporation of plasticizers caused by exposure to heat, UV rays, etc.
- When hoses are used to carry hot fluids, it is important to carefully check their permissible temperature and select a hose with high heat resistance.
Learn the secret behind what makes PVC hoses flexible
Now, here’s a question for everyone from Hose Adviser PRO.
Why do soft PVC hoses harden during use?
Select from among A, B, and C below.
A. Because the plasticizer is exuded to the surface
B. Because fluid repeatedly flows through the hose
C. Because air gets trapped in the hose
The answer is A. Because the plasticizer is exuded to the surface.
So, what do you know about plasticizers? They are closely related to hose softness. Let’s take a closer look.
The polyvinyl chloride (PVC) resin mainly used for hoses is hard at room temperature and cannot be bent. When heated to a certain temperature (the melting point), however, the material becomes softer. This is its thermoplasticity. To keep the material soft, an additive called a “plasticizer” is added to the PVC resin, forming a soft PVC resin.
What is the mechanism behind heat causing PVC hoses to harden?
The effect of the plasticizer may decrease over time due to heat, UV radiation, and other external factors that cause the plasticizer to be exuded to the surface. This is why hoses used under high temperatures or in the sun, or those left unused, become hard and unusable or form a sticky surface. Also, hot fluids inside a hose can result in fast elution of the plasticizer, causing the hose to harden shortly after use.
Because hardened hoses can cause hose punctures (ruptures) and cracks, it is essential to replace them as soon as possible. To prevent increased replacement frequencies, measures must be taken to prevent hoses from hardening due to heat.
The effect of the plasticizer may decrease over time due to heat, UV radiation, and other external factors that cause the plasticizer to be exuded to the surface. This is why hoses used under high temperatures or in the sun, or those left unused, become hard and unusable or form a sticky surface. Also, hot fluids inside a hose can result in fast elution of the plasticizer, causing the hose to harden shortly after use.
Because hardened hoses can cause hose punctures (ruptures) and cracks, it is essential to replace them as soon as possible. To prevent increased replacement frequencies, measures must be taken to prevent hoses from hardening due to heat.
How to prevent your hoses from hardening due to heat
A wide range of hoses are available for a variety of purposes, but not every hose can be used for a given purpose. PVC hoses, for example, should not be used with high-temperature fluids because the heat will cause the plasticizer to elute, resulting in hardening of the hose. To ensure safe and stable use by preventing hoses from hardening and reducing the likelihood of punctures (ruptures) and cracks, it is important to choose the right kind of hose with a high heat resistance.
If heat resistance is especially important, check the permissible operating temperature of each hose to make the best choice. For example, hoses made from a heat-resistant material, such as silicone rubber, are highly effective for carrying hot fluids.
If interested in silicone rubber hoses, please check the product information below.
TOYOSILICONE Hose Series
Heat-resistant, flexible, and many food-grade types available
In addition to silicone rubber hoses, we also recommend the following highly heat-resistant products.
FUSSOTHERMO-S100°C Hose
For a wide range of applications requiring heat resistance, non-adhesiveness, and water repellency
TOYOTOP-E100°C Hose
Highly durable and antistatic for use with powder and granular materials
Toyox offers a wide variety of hoses, including pressure feed and suction hoses, antistatic hoses, and food-grade hoses—all with different heat resistances. Be sure to check the type and temperature of fluids being used as well as the pressure, size, and length of hose required, and the necessary functionality when making your choice.
That wraps up our explanation on the causes and countermeasures for punctures (ruptures) and cracks caused by heat.
For any other inquiries or consultations, please contact the TOYOX Customer Service Office.
Hoses can harden over time for a variety of reasons, including the temperature and type of fluid they carry (chemical, oil, etc.), the environment they are used in, and how long they have been in use. Hardened hoses cannot be returned to their original condition and can cause not only punctures (ruptures) or cracks but also various other problems. In this article, Hose Adviser PRO will explain causes and countermeasures for punctures (ruptures) and cracks caused by heat.