The Advantages of Synthetic Lubricants in Industrial Applications
Think: longer service life and extended drain intervals
Synthetic lubricants have been in use in industrial applications for over two decades. Although they are three to four times more expensive than mineral-based oils, the payback is potentially huge due to their longer service life and the efficiencies they can deliver. It’s useful to understand the advantages of synthetics and the range of synthetics available for different applications.
In on-highway engine oils, the primary driver of the trend toward lower-viscosity synthetics is regulation calling for improved fuel economy. That’s not a concern in industrial equipment, but synthetics will deliver very similar energy efficiency improvements. In gear boxes, for example, a synthetic lubricant reduces the traction coefficient in the rolling elements, resulting in smoother operation with less power consumed.
Synthetics also give you a wider operating temperature range than conventional oils. At lower temperatures, synthetics deliver better fluidity and reduce the risk of wax crystallizing out of the oil. You can start equipment and get it running much more quickly in low temperature applications. At the other end of the thermometer, synthetics will generally give you about a 100o F higher temperature operating range than a mineral oil. This explains the popularity of synthetics in extreme temperature environments and applications.
The third major benefit, and perhaps the biggest, is better oxidation resistance, which leads to longer drain intervals and less frequent oil changes. That translates to improved operating efficiency and potential cost savings for your plant. You will also see greater efficiency in throughput because of less internal friction and, as noted earlier, the wider temperature range.
Together, these benefits result in overall improved operating efficiencies. In some applications – for example, a cooling tower in a power generation plant – operators might think they have to use one oil viscosity in summer months, and then go to a lighter viscosity oil in the winter. With a synthetic, the wide operating range allows you to leave the same oil in all year round – and maybe even longer, because of the oxidation resistance and longer drain intervals. Not only do you get longer life out of the oil, but you also reduce inventory complexity, and save on labor and downtime associated with seasonal oil changes.
A Wider Variety of Options
A major difference between industrial synthetics and engine oils is the wider range of base stocks used for different applications. Synthetic engine oils are derived primarily from polyalphaolefin (PAO) or Group III base stock, and are typically compatible with their mineral oil counterparts, which reduces the risk of cross-contamination when switching from a conventional to a synthetic oil. Synthetics for certain industrial applications also use PAO and Group III base oils, but there are several other synthetic types that are preferable to a PAO in specific applications.
For example, an application might call for fire resistant fluids if there is a risk of the oil coming in contact with an open flame. You can use a phosphate ester-based lubricant or a polyolester, the former being more fire resistant. In air compressor applications, diester fluids are common. A diester can break down into its basic components without leaving deposits, which is a big benefit. Polyalkylene Glycol or PAG (in contrast to PAO) has merit in some gear applications. PAGs are highly polar. Both water soluble and insoluble forms are available and they have a better friction coefficient than a PAO in gear box applications.
All these ester and PAG oils, however, present compatibility issues with mineral oils and PAOs, as well as with some of the seals and paints in industrial units, calling for extra caution when introducing some of these unique synthetics into industrial applications.
Silicones represent another class of base oils. Some air compressors utilize silicone fluids because they have excellent oxidation resistance, as well as a favorable viscosity index (meaning temperature changes do not cause changes in viscosity). However, their load carrying capability is minimal compared to mineral oils or other synthetics. And if you try to convert to another base stock, you’re likely to have excessive foaming if there is any residual silicone.
Switching over to synthetic oil in an industrial application should proceed with caution and care. You need to identify the synthetic base stock to make sure it’s compatible with the fluid you’re replacing or do a thorough job of flushing out the older oil. If you can keep a synthetic in a component three or four times as long as the comparable mineral oil – and keep it free of particulates and contaminants that entire time – you will not only see performance benefits, but the economics will make sense as well. As always, we are here to guide you in the selection and proper handling of synthetics for your industrial applications.