Effective lubrication of chains operating in a harsh, abrasive atmosphere can be challenging. The objective with chain lubrication is to place a small quantity of lubricant between the pin and the barrel in each link. Because it is impossible to directly inject the lubricant to the correct locations, practitioners try other methods, including running the chain through a bath, spraying, pouring and painting lubricant on the chains outer surfaces.

For slowl turning chains, the oil bath is a practical, useful approach. Some attention is required to maintain an appropriate sump level and clean any excess lubricant off of machine surfaces. Chains tend to be lubricated with whatever is handy. Slow-turning, heavily loaded chains require a heavy body of oil. A medium gear or heavy circulation oil is a common choice.

For intermittent relubrication practices, any lubricant coating on the exterior of the chain creates an opportunity for airborne debris to build up and choke off oil flow to the internal components. Additionally, depending on the hardness of the airborne contaminant, this wetted material may act like a grinding compound working against the sprocket and barrel of the chain. These applications are good candidates for lubricants with solid film additives mixed with a light, evaporating carrier. The light oil penetrates, carrying the solid additives to the contact point. The solid additives remain behind to provide "dry film" protection after the carrier has been displaced. Additionally, the exterior of the chain does not accumulate as much atmospheric contaminant.

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Book Bits: Advice for Using Grease Guns

From "Lubrication for Industry"

In order to move grease to the application point, it needs to be pumped. Most delivery systems for oil utilize pumps that work in the 50 psi (2.3 bar) to 250 psi (17.2 bar) range. Grease, on the other hand, requires a pump that will deliver pressure above 1500 psi (103 bar).

In the hands of an untrained operator, an ordinary grease gun can deliver a pressure of up to 15,000 psi (1030 bar)! A bearing seal, on the other hand, will rarely rate higher than 500 psi (35 bar). Once the seal on the bearing is compromised, the bearing is well on its way to early failure. A compromised bearing seal encourages dirt ingestion and overlubrication due to its lack of "back pressure" (this is especially true when greasing a bearing "blind" from a remote zerk fitting). The secondary negative effects produced are extra consumption of grease and extra time required for cleanup of equipment with the overflowed grease, inviting dirt and contaminants to stick to it. Respect the power of a lowly manual grease gun.

Maintenance Tip: Always ensure that the dispensing nozzle of the grease or oil gun is cleaned before use, and that the fitting it is attached to is also clean. This will safeguard against unnecessary introduction of dirt into the bearing.

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"How do I know if I have water in my hydraulic oil?"

Water in oil can be either dissolved, emulsified or free. Dissolved water must be discovered through the use of oil analysis or capacitance-type dew point meters (available online or portable). Dissolved water cannot be visually observed. Emulsified water will show up in the form of a cloud or slight haze in the oil. Free water can be seen at the bottom of the reservoir or in a bottom sediment and water bowl (BS&W) installed at a convenient low point in the reservoir.

While most would like to maintain completely water-free sumps, it is likely that most hydraulic reservoirs will have some amount of dissolved water. Take action if the oil becomes cloudy or if the PPM level rises above roughly 350 PPM (0.035%) for most industrial applications. On-site or in the field, free and emulsified water can be detected using the crackle test (hot plate or soldering iron) or by the calcium hydride method.

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