Publié le 2020-10-29
A US food processing plant uses hydraulic drive systems to operate "dumpers" in materials handling applications throughout the facility. Mineral oils were originally used for lubrication and motion transmission in this equipment. The mineral oil based product contained a zinc additive and was rated at 20W (46 ISO) with a viscosity index (VI) of 98.
During daily washing, pressurised water from the spray cleaning equipment would impact the oil tanks located under the skips. Some of the water would mix with the oil and form a thick, sticky emulsion. It was not uncommon for the service to stop with "OK" oil after washing and then discover at start-up that the oil had to be changed due to water contamination.
Because the emulsion degraded lubrication performance and the ability of the oil to circulate properly in the hydraulic system, this plant typically performed oil changes at 30-day intervals, well before the rated life of the oil.
Frequent (daily) washing with spray equipment exposed the oil tank underneath the equipment to pressurized water. Conventional mineral oil combines easily with water and emulsifies, resulting in frequent oil changes. Premature changes resulted in increased annual oil expenses and increased labour costs to change the oil, frequently interrupting production.
The switch to a new synthetic oil has eliminated the formation of an emulsion on contact with water. The new oil operated successfully in the hydraulic system for a nominal service life of six months. The plant achieved significant savings through reduced oil consumption, disposal costs, labour savings and production interruptions.
Lubricating your hydraulic system with Molykote® synthetic hydraulic oils is a cost-effective way to prevent premature lubricant failure and extend maintenance intervals. Unlike oils produced by conventional fractionation processes, synthetic oil is produced by combining smaller molecular "building blocks" to meet targeted performance specifications and to minimise impurities. As a result, synthetic oil is inherently resistant to emulsification, reducing friction and oil change frequency.
In order to avoid the costly formation of emulsion in the oil, the maintenance manager switched to Molykote® hydraulic oil, a DuPont product. This oil also has a viscosity of 20W (46 ISO) with a VI of 147. The anti-wear (AW) additives in the synthetic oil comply with ASTM D 2882, the standard for piston and vane pumps used for pressures below 2000 psi. Unlike original oil, which is manufactured using conventional fractionation processes, synthetic oil is designed by combining smaller molecular "building blocks" to meet targeted performance specifications and to minimize impurities.
During a trial period, the oil was sampled and analysed at regular intervals. The results indicated that the fluid remained in good condition.
The installation of the synthetic hydraulic oil followed a complete change of the old oil. The new oil was checked every month using analyses of oil samples provided by the supplier. It worked successfully for 6 months, when the tested anti-oxidant was exhausted. No special rinsing liquid was used. No signs of emulsification occurred during the lifetime of the oil. Sampling of the oil revealed the presence of zinc additives, which were remnants of the original product.
Residual acid zinc additives generally shorten the life of the antioxidant used in synthetic oils. After the first change of the new oil, the life of the oil increases as the amount of residual zinc decreases.
You can also download our selection guide dedicated to industrial lubrication and maintenance:
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