Constant level oilers are designed to maintain a predetermined oil level in a sump, which is necessary for proper lubrication. If the oil level were to drop below this point, the depleted oil would automatically be replenished by the lubricator, returning it to its original level. Using constant level oilers can help increase maintenance efficiencies as well as, decrease maintenance costs, and loss of production time. Even though constant level oilers are simplistic and easy to install, problems can still arise.  Care should be taken when installing, applying and refilling these units.

Installation/Application

Prior to installing a constant level oiler, the direction of shaft rotation must be determined.  If a side mounted connection is required, the recommended placement is on the side of the equipment, facing the direction of shaft rotation (Fig.1). This positioning protects the oiler from oil sump surges that can occur during start up, which may cause the oiler to overfeed.  If frequent start ups are necessary, the bottom mount configuration is recommended (Fig.2). In some cases, eddy currents and oil turbulence can form due to slinger rings, discs, and high rotating speeds. These currents can temporarily alter the level of the oil and ultimately cause the oiler to overfeed. When these rings or discs are present, mount the lubricator using the bottom fitting, and connect it to the bottom of the equipment’s sump (Fig.2).  Check lubricant levels periodically to ensure proper application. 

Many oilers contain a small vertical stem, some are fixed to the unit, and others are part of a leveling assembly (Fig.3).  The purpose of this stem is to break the meniscus, allowing the oil to feed properly through the unit.  Often times, when these stems are part of a removable assembly, they are discarded during maintenance, causing the oiler to mis-feed or not feed at all.  Prior to installation, or after maintenance, verify that all parts of the lubricator are accounted for.

When using a constant level oiler that is vented to the outside atmosphere, it is important to keep the oiler and/or the breather vent away from any air flow near the equipment. Sources of this air flow can be any type of fan, such as a blower fan, motor fan, etc.  Fans create an air flow over the breather vent or the oiler, causing a pressure differential between the bearing housing and the oiler, leading to mis-feeding.

Pressure differential from air flow

To prevent this occurrence, install an extension pipe nipple on either the breather vent or the oiler connection.  Replacing the vented constant level oiler with a non-vented or “closed system” oiler is an additional solution that also eliminates contaminant ingression. 

Note: When installing an extension pipe on the vented oiler in a side mount configuration, do not use an elbow fitting, this will change the fluid level in the oil sump.

Closed System oilers operation and installation considerations are similar to vented oiler. However, the closed system requires a vent tube be connected from the lubricator to the bearing housing for pressure equalization.  Additional types of closed systems oilers are available that mount directly on equipment that has a port at the centerline of the oil level.  This type of mounting does not allow for fluid level adjustability, eliminating potential installation errors. 

Improper filling methods

Care should be taken when replenishing fluids to predetermined levels.  Understanding proper filling methods is important in preventing overfilling of the sump.  Although constant level oilers are simplistic in function, several misconceptions are often made such as, filling through the top, surge body and frequency.

When filling through the top of the equipment, knowing the required oil volume is necessary to achieve the preset level. If you are confident the oil quantity is known, then this method is considered to be a safe filling procedure. However, more times then not, the oil quantity is unknown and is haphazardly filled through the top, using a sight gauge to determine the level.  Unfortunately, this will result in a high fluid level due to residual lubricant draining from the internal components such a shaft or gear.

Proper filling can be achieved through the surge body when a sight gauge is present.  The sight gauge provides a visual aid for achieving the predetermined fluid level in the sump. Filling, without a sight gauge can cause overfilling of the oil sump and surge body.  An indication of overfilling will become evident if fluid begins flowing from the surge body once the reservoir is replaced.  To adjust for overfilling, drain the lubricant from the sump until the constant level oiler begins feeding, and reaches the preset level.

In addition, excessive refilling of the reservoir will also have a negative effect on the oil level.  Each time the reservoir is removed and replaced, a small amount of lubricant is added to the oil sump level.  Overtime, this will increase the fluid level. To combat this incidence, refill the reservoir only when it is half full or less.  This will help minimize unnecessary filling.

Conclusion

Constant level oilers are an easy and effective method of maintaining proper oil level in equipment. Proper installation and usage will provide optimum performance of the lubricator as well as the equipment it supplies.  By implementing the recommended guidelines, efficient and effective lubrication management can be achieved.

Front Page