Which hydraulic oils are used in scissor lift tables?

• 1. Different types of hydraulic oils and their applications
  • 1.1 Conventional hydraulic oil
  • 1.2 Biodegradable hydraulic oil
  • 1.3 Biodegradable, non-water-polluting hydraulic oil
  • 1.4 Food-grade oil
  • 1.5 Other oil types
• 2. Distinction based on viscosity
• 3. Are there additional selection criteria?

In this article, you will learn how to select the right hydraulic oil for a lift table and which factors to consider when making a decision.

Hydraulic oils can be categorized based on their base materials. These categories are specifically tailored to different applications and areas of use:

Conventional hydraulic oils are primarily based on mineral oil, which is derived from the refining of crude oil. By adding additives, the base oil is specifically modified to ensure properties such as application-optimized viscosity and increased oxidation stability.

A well-known product in this category is hydraulic oil HLP 32, which complies with DIN 51524-2. It is a proven choice for scissor lift tables and goods lifts when there are no special requirements, such as extreme temperatures or environmentally sensitive areas.

Biodegradable hydraulic oils were developed as early as the 1980s but only became widely adopted after various advancements in the late 1990s.

They are particularly used in hydraulic lift tables operating in environmentally sensitive areas, such as outdoor applications where direct contact with the environment cannot be ruled out.

Despite their faster degradation compared to conventional alternatives, appropriate protective measures are still required to prevent leaks and potential environmental contamination.

These hydraulic oils are not water-soluble, meaning they do not mix with water in the event of a spill. Instead, the oil remains in the soil, where it is biologically degraded without directly contaminating groundwater.

Non-water-polluting hydraulic oil should be used wherever there is a risk of hydraulic oil entering groundwater or surface water.

In Germany, hydraulic oils are classified according to Water Hazard Classes (WGK), ranging from "highly hazardous to water" to "slightly hazardous to water." Additionally, substances can be classified as "non-hazardous to water" (formerly WGK 0) if they are registered with the German Federal Environment Agency (Umweltbundesamt).

Food-grade oils are used in the food industry, particularly in machinery and equipment that comes into contact with food. Only approved base oils that comply with strict legal requirements may be used. The use of additives is also highly regulated to ensure compliance with hygiene and safety standards in food production.

In addition to the oils mentioned, there are numerous specialty oils developed for specific applications. One example is fire-resistant hydraulic oils of classes HFA to HFD, which are used in areas with heightened fire protection requirements.

Viscosity describes the thickness or flow resistance of liquids and gases. The higher the viscosity, the lower the fluidity of the substance.

Hydraulic oils are classified into viscosity grades, which are based on flow behavior at a temperature of 40°C (e.g. 22 mm²/s for ISO-VG 22). A higher viscosity grade indicates a thicker oil – for example, ISO-VG 46 is more viscous than ISO-VG 22. Common viscosity grades for hydraulic scissor lift tables include ISO-VG 22, ISO-VG 32 and ISO-VG 46.

Why is the viscosity grade important?

Selecting the correct viscosity grade is essential for the functionality and service life of a lift table.

• Oil that is too thin: If the viscosity is too low, there is a risk of lubrication film failure, leading to increased material wear.
• Oil that is too thick: If the hydraulic oil is too viscous, the pump may struggle to circulate it, reducing system performance.

Viscosity is also highly temperature-dependent. As the temperature rises, oil becomes thinner, and as it falls, oil becomes thicker. To determine the correct viscosity grade, manufacturers need information about the drive's duty cycle and the operating environment's temperature.

Measures to maintain optimal viscosity

In cases of extreme temperatures or heavy use of the lift table, it may be necessary to equip the hydraulic system with an oil cooler or oil heater. These measures ensure that the hydraulic oil maintains its optimal viscosity and that the system operates reliably.

Choosing the right hydraulic oil involves more than selecting the oil type and viscosity grade. Factors such as heat dissipation, compatibility with installed seals and the lubrication of components within the hydraulic system also play an important role.

However, considering these factors is the responsibility of the lift table manufacturer. In this article, we have deliberately focused on the criteria where your input as the customer is required.

To determine the appropriate hydraulic oil, the manufacturer needs the following information from you:

• Location of the scissor lift table: For example, is the lift table used in a food processing facility or a production hall?
• Ambient temperatures: Will the lift table be used indoors or outdoors, and what are the typical temperatures in the environment?

Providing this information helps the manufacturer identify the optimal hydraulic oil solution tailored to your specific requirements.