Pneumatic cylinders and extreme temperatures

Extreme temperatures: choosing pneumatic cylinders

Just like dirt and dust, temperature is a challenge for every machine builder. Will the machine or application be located in an extremely cold environment or in a very warm environment. Or does the temperature vary enormously? And how does a pneumatic cylinder react to this? In this blog we will explain what the problems and challenges can be, what possibilities Festo offers and which product ultimately can be chosen best for a particular application and temperature range.

Machines in cold environments are known to everyone. In the food and pharmaceutical industries, cold stores and freezer rooms are the most normal thing in the world. But also machines that are placed outside must be able to withstand extreme conditions, such as cold. On the other hand, machines in warm or hot environments are also ubiquitous in certain branches of industry. Think of ovens, frying pans with hot oil, dryers and autoclaves. In addition, machines are often cleaned with hot water, chemicals or steam. This also affects the pneumatic cylinders.

Challenges and problems at low temperatures

So there are a number of challenges when it comes to temperature. But what actually happens to a pneumatic cylinder in extreme cold? A number of things. First of all, the elasticity of the seals is reduced. In addition, the grease in the cylinder becomes viscous and there is a chance of ice crystals forming on the piston rod.

This certainly has an effect on the operation of the cylinder. Air can start to leak at the seal because, due to reduced elasticity, it no longer fits as well on the piston rod. Because the grease becomes more viscous (thicker), the cylinder runs less smoothly. There is also a higher breakaway torque of the piston in the cylinder, i.e. the piston overcomes its resistance and shoots forward. And do not underestimate ice crystals. If they get on the piston rod, they will cause grooves (wear) in the seal.

Festo has various solutions for pneumatic cylinders in a cold environment.

  • Almost all cylinder variants are suitable for temperatures down to -20°C.
  • For colder temperatures down to -40°C, the cylinder version TT/T3 is suitable
  • An exception is made for cylinders with FKM seals (version A1, S6). These are only suitable for temperatures above 0°C.

A cylinder for extremely low temperatures down to -40°C (T1/T3)

Cylinder variants specifically for use at low temperatures (T1/T3) are best suited for use outdoors and in refrigerated environments, with frozen products (cold stores) and environments such as cold stores where high temperature fluctuations occur around or below freezing. This variant is also suitable for applications where the piston rod is loaded with dust, crystals (ice and milk) and viscous substances.

Advantages and points of attention

The cylinder for low temperatures (T1/T3) offers various advantages. This cylinder is suitable for a temperature range from -40°C to +80°C. This is due to the special PUR seal and special lubrication for low temperatures (grease Spheerol SLC 2). Another advantage is the scraping function for keeping out solid particles such as ice, milk and sugar crystals that stick to the piston rod. In addition, this type also offers a good scraping function for viscous media such as paint, oil, glue, etc.

A point to note when choosing this type is that pneumatic cylinders with this variant are longer, as the scraper requires extra inner space. The cylinder is 6 mm longer than a conventional ISO 6432 cylinder. This must be taken into account when designing the machine.

Another consideration is that this cylinder is less resistant to humid environments and chemicals.

Which cylinder series?

  • The T1/T3 version is available for cylinder series DSBC (T3) and CRDSNU (T1).

Challenges and problems at high temperatures

Even at high temperatures, there are a number of challenges that the engineer must face. There is a limited resistance of pneumatic cylinders to high temperatures. This is mainly due to the seals and lubricants. The lubricant becomes thinner reducing its performnce. This in turn increases the resistance between the piston and seal. A higher temperature can also affect all the seals in the cylinder, including the static seal and the piston seal. There is also a greater chance of chemical reactions with certain agents in the vicinity of the cylinder such as biological or chemical cleaning agents and the use of steam.

Festo has various solutions for pneumatic cylinders in a warm environment.

  • For high temperatures, the cylinder version with heat-resistant seal S6/T1/T4 is suitable.
  • For short-term peaks in temperature, the standard cylinder with PUR seal is suitable.
  • The A1 version is unsuitable for high temperatures due to its lubricating grease and FKM seal.

Cylinder for extremely high temperatures (S6/T1/T4)

Cylinder variants specifically for use at high temperatures (S6/T1/T4) are best used in or near ovens, frying pans with hot oil, dryers and autoclaves. In addition, machines are often cleaned with hot water, chemicals or steam. A distinction is made between temperatures up to 120°C (non-food applications), up to 150°C (food applications) and whether or not there is contact with acids and oils at high temperatures.

Benefits and considerations

The cylinders for high temperatures (S6/T1/T4 in the type code) offer various advantages. The S6/T1 cylinder variant is suitable for a temperature up to +120°C. The T4 cylinder version is suitable for temperatures up to +150°C. All three versions are resistant to the use of acids and oils at high temperatures thanks to FKM heat-resistant seals and special grease. That includes the static seals and the piston seal.

A point to note when choosing this type is that pneumatic cylinders of this type are not suitable for use with dirt particles such as rust and dust. This is due to the low yield strength of the FKM seal. Cylinders S6/T1/T4 also have a low chemical resistance to bases and alkalis with a pH value > 9.

Which cylinder series?

  • The T1 and T4 version are available as an option for cylinder series DSBx.
  • The S6 version is available as an option for the DSNU and CRDSNU cylinder series.

Has this blog given you more insight and knowledge about using pneumatic cylinders at extreme temperatures? Please feel free to contact us for more advice or tips.

July 2022