Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1222953
4 | March - April 2020 | www . machinerylubrication.com AS I SEE IT TRAPPED HEADSPACE MOISTURE FOLLOWS A PRECIPITATION CYCLE Trapped moisture is destructive to lubri- cants and machines. The headspace needs to have the ability to breathe and exhaust unwanted moisture. Of ten, this is prevented by reservoir design and the false notion that a sealed reservoir is a good thing. This is how it works: The Precipitation Cycle: 1. The headspace holds moisture. Lack of air movement and breathers prevent moisture from exiting. 2. The machine is turned off for a few hours each day, and the headspace and oil cool. 3. Condensation sweats the headspace ceiling and walls. 4. Water drips into the oil where it is absorbed, and free water puddles on the sump floor. 5. Later, warm, circulating oil picks up the water. 6. Circulation and heat allow the water to evaporate back to the headspace. 7. The cycle repeats each day. Inspection, oil analysis and condi- tion monitoring can also be important strategies for providing red-code alerts to periodic water ingression problems. is can be as simple as daily visual inspection of BS&W (bottom, sedi- ment and water) sight glasses, level gauges and live-zone oil samples. In addition to visible inspection, water also can be detected using a number of field-level instruments and pass/fail methods such as the crackle test and calcium hydride detectors. Once a new source of water is encoun- tered, corrective measures can be quickly deployed. When gross water contami- nation is observed, there is little need to quantify the exact amount in the oil. Look for Evidence of Moisture and Other Contaminants in Your Headspace Water removal is the second reason why stabilizing the headspace environ- ment is important. With rare exception, a dry headspace translates to dry oil — they go hand-in-hand. is is because wet is attracted to dry in the same way hot is attracted to cold. Basically, a dry headspace forms a desiccant blanket above the oil and, like a sponge, draws water out of the oil. e lower the relative humidity of the air in the head- space, the faster and more efficient the process of mass transfer of water out of the oil becomes. Rainmaker machines can overwhelm lubricant rust-suppression additives. EXAMINE TANK-TOP HARDWARE FOR HIDDEN INGRESSION SITES • Inspection hatches should hinge down against gaskets and be held by compression clamps or bolts. • Roll filter covers should be sealed tight in a similar manner. • All tank-top ports, such as vertical-entry float switches, flanged return ports and breather blower connections, should be sealed and elevated. • Where possible, fill ports should not be used as a vent/ breather. • Male quick connects with dust covers are best for adding make-up oil (while filtered). • Off-line filters can serve a similar purpose. This headspace breather is installed but not being used. Air has easier access to the tank headspace through the hatch, which is propped open by the hose. Inspection must verify that all ingres- sion sources are battened down tightly and can effectively exclude the entry of particles, moisture and other contaminants. Of course, there are other contaminants besides water and dirt, such as air, sludge and heat. However, many lubrication professionals are unaware of the impact of dirt and water contamination on other contami- nants. For instance, when emulsified water is allowed