HFC vandens-glikolio alyvos
- ISO 6743/4 – HFC
- ISO 12922 – HFC
- 7th Luxembourg Protocol
HFC or water glycols fluid
are the most popular of the fire resistant hydraulic fluids. They consist of 35-45% water with special viscosity-boosting thickeners. These fluids can run most equipment that has been designed for oil, but pump speeds, temperatures and pressures may have to be modified. Their water content, which provides fire resistance, must be monitored and maintained to prevent evaporation. In contrast, the fourth type of fire resistant fluid is considered synthetic because it has no petroleum oil or water. The most widely used HFD fluids are polyol esters, which are based on organic esters. These high-performing fluids are compatible with system materials. Furthermore, they are biodegradable and display low levels of aquatic toxicity. However, polyol esters can be more than twice as expensive as petroleum oil so their use is limited to applications where fire resistance or biodegradability is extremely important.
Environmental issues such as biodegradability and toxicity figure into fluid selection. Petroleum oils are not biodegradable and as a result, fluid leakage often leads to soil contamination and the destruction of marine life. Environmental fluids have been developed as options. Although specifics may vary according to government or local laws, in general, an environmental fluid must be readily biodegradable—meaning that 60% of it must decompose within 28 days of exposure—and non-toxic—passing aquatic toxicity tests on specific species of fish. Vegetable oil—usually rapeseed oil—forms the most common base for these environmental fluids. Vegetable oil-based fluids feature lubrication and anti-wear properties that match that of petroleum oil. However, these products are susceptible to oxidation and perform poorly in cold weather, during which they can congeal and exacerbate cold starting. Synthetic base fluids present another popular environmental option. Examples such as polyol esters and water-free polyalkalene gycols (PAGs) are both environmental and fire resistant. They excel at preventing oxidation and at low-temperature performance. Environmental fluids are continually being improved with vegetable oil suppliers employing genetic engineering to boost fluid stability and ester manufacturers developing molecules that will yield even better performance. Applications for these fluids already include agricultural, forestry, mining and construction machinery, among others
Today’s hydraulic systems have high pressures and tight tolerances. While many hydraulic system users are drawn to petroleum oil’s combination of high performance and low cost to fulfill these requirements, other factors must be examined. For example, many applications call for hydraulic fluids that are environmental and fire resistant—two properties that petroleum oil lacks. In these instances, users must find the best fit, considering both hydraulic fluid properties and system needs.