Using the correct breathers for proper headspace management is a decision that is sometimes taken lightly in industrial facilities. There are many instances when makeshift breathers are used to provide air filtration for very expensive and critical equipment, or no breather is employed at all.
This mind-set that a “breather is a breather” will inevitably lead to costly failures and downtime in the future.
To create and manage a world-class lubrication program, you must consider all factors that influence the performance and life of a lubricant. Using the correct breather to exclude contaminants is one of these influencing factors.
The breathing of equipment is vital to its performance. It allows for the contraction and expansion of the headspace to prohibit the fluids inside from pressurizing the system, which could lead to leaky seals, inadequate level readings and other negative side effects.
Proper headspace management keeps equipment lubricant clean and maintained, which keeps that equipment running smoothly. Three major factors influence the quality and cleanliness of a lubricant: monitoring, removing and excluding.
Monitoring uses technologies such as oil analysis to monitor the ingression and generation rate of contaminants. Removing uses technologies such as offline filtration (static or mobile) to remove digested or generated contaminants.
Excluding uses technologies such as contamination control with proper breathers and hardware to help make the system completely closed to external contaminants.
Of these factors, only one of them contributes to the other two, excluding. If contaminants are not excluded properly, more monitoring and removal is required. Therefore, excluding should be the first task to conquer.
Expansion Chambers, Desiccants and Hybrids
There are three primary types of excluding devices on the market:
Expansion chambers allow for expansion and contraction of the headspace without breathing or exhausting to the atmosphere.
Desiccant breathers use desiccating material to draw moisture from the inhaled or exhaled air.
Hybrid breathers, a combination of an expansion chamber and desiccant canister, can allow small expansion and contraction of the headspace without fully “opening” the desiccant media to the atmosphere.
Expansion chambers do an excellent job at excluding, but they are not so great at conditioning the already trapped air. Basically, expansion chambers allow the headspace to expand and contract without having to inhale or exhale atmospheric air.
This simple concept allows for exceptional contaminant exclusion, but does not do anything to condition or remove moisture or airborne particulates from the headspace. To alleviate this problem, simply install a non-breathing/venting desiccant canister alongside the expansion chamber or in a separate auxiliary breather port.
While the expansion chamber compensates for headspace contraction and expansion, using a separate non-breathing/venting desiccant canister allows the headspace to be filtered of moisture since desiccant material is hygroscopic.
Desiccant breathers are great for excluding particulate contaminants and moisture. A desiccant breather works by inhaling or exhaling air through a desiccating media, which attracts and absorbs moisture, helping to keep the headspace dry. Since these breathers are “always open”, their life expectancy can be very short.
This always-open principle allows air to move through the media upon headspace expansion and contraction, and is constantly absorbing moisture from the surrounding environment, whether the machine is running or not. Depending on how humid or wet the surrounding environment is, desiccant breathers may last only a few days.
Hybrid breathers are superior to plain desiccants in their exclusion of particulates and moisture. They operate on the same principle as having an expansion chamber plus a desiccant canister installed, but hybrids get the same results in one compact unit.
Hybrids have a bladder inside which acts like an expansion chamber and a separate desiccant media to filter out moisture from inhaled or exhaled air. The difference here, when compared to traditional desiccant breathers, is that hybrids are “normally closed” to the atmosphere.
Therefore, their life expectancy is four to six times that of a traditional desiccant breather. Depending on the required volume of headspace expansion and contraction, the bladder may or may not need to open the system to the atmosphere.
If the required volume is large, the system opens to the atmosphere, inhaling or exhaling air while at the same time filtering out moisture and particulates. If the required volume is small, the system remains closed and captures moisture from the headspace.
Make Educated Decisions
Many times when plant professionals are deciding on the type of breather to use, it often depends on the up-front costs. With disposable desiccant breathers, the up-front cost is much less than a hybrid breather, but the life expectancy of a hybrid breather can be four to six times that of a traditional desiccant, which results in more value for the investment over a given period of time.
When using a misguided or misinformed selection technique, the end result is usually a makeshift breather or no breather at all, resulting in possible equipment damage.
This is where proper education of breathers and their functions are crucial to the success of headspace management. Be sure to read and understand the types of environments for which certain breathers are designed and compare them with your environment to make a well-informed decision.
Choosing the right breather for your application will provide returns, not just in breather life but in equipment life. Remember, proper headspace management starts with having the right breather.