The Squeaky Wheel Gets the Oil…or in this case, the Squeaky Elevator
You press the button and wait. Four…three…two…one! The doors part way and a sea of suits, brief cases in hand, flood out of the elevator. As fast as the elevator empties, it swiftly fills back up as people file in amid the morning rush. Once inside, the push buttons light up like a Christmas tree; two…four…five…seven. Up you go, ascending from the ground level as the elevator car makes its way to your final destination, your floor. Amidst the hustle and bustle of your morning routine, it’s probably not often that you think about the importance of the hydraulic oil in the elevators we so often use to get us where we need to go. Let’s face it; an “Out of Order” sign is not exactly what you want to see posted on the elevator you take to your Monday morning meeting. If your company’s building maintenance team is properly maintaining the oil in their hydraulic elevators; before you head into the board room, you should never have to walk up five flights of stairs due too an unexpected elevator shut down.
Hydraulic oil is a fundamental piece to the puzzle within the hydraulic elevator industry. The oil is undoubtedly one of the most vital mechanisms within any hydraulic system. Yes, hydraulic oil is a lubricant that prevents the occurrence of friction, but its key role is to assist in the transfer of power within the system. Hydraulic oil transmits the energy generated by a pump to the cylinder. Typical hydraulic elevator installations use AW 32 Hydraulic Oil. Most hydraulic elevators use fifty five gallons of oil per floor. Hydraulic elevators can go as high as seven floors. An average is three floors or one hundred sixty five gallons of oil needed per elevator. Needless to say, without hydraulic oil, an elevator is going nowhere…fast! Considering the fact that hydraulic oil plays such a crucial role in the elevator world, it is essential that the hydraulic oil is properly maintained. Appropriately maintaining the oil ensures that hydraulic elevators can operate safely and efficiently. A key problem within the industry is that elevator companies do not change the oil in their elevators until an issue presents itself, such as, overheating, water damage, or a related system failure occurs. There are many elevators in use today that have not had their oil changed since the time of their installation, which in some cases, was many years prior to running into performance issues. Elevator maintenance contracts call for “routine” oil changes, but are not always definitive as to when or how often. So, how frequently should the hydraulic oil in elevators be changed? By contacting elevator manufactures, hydraulic oil companies, and hydraulic oil testing firms within the industry via email, phone, and online information submissions; a consolidated overview of the feedback given by specialists, on behalf of these companies, should help fuel the need for increased regulation and understanding as to how often the oil in hydraulic elevators should be changed.
Prompted with the topic at hand and asked for their recommendations, elevator industry experts explained that there are a multitude of factors to consider when deciding on the regularity of oil changes. It is nearly impossible to just declare “Change the oil every X amount of years!” There are various aspects that must be taken into consideration when trying to estimate how often the oil in hydraulic elevators should be changed. Influences such as location, usage, contamination, proper elevator room temperatures, and ventilation are all significant. With so many factors to consider, each circumstance will vary. Due to the abundance of factors that must be taken into consideration, oil analysis testing is the best way to know when an oil change is required.
In the process of oil analysis, a technician takes a small sample of oil from the hydraulic power unit of the elevator. The sample of oil is then sent to an oil testing firm, or laboratory, where it is evaluated. An oil analysis will check the viscosity, impurities, and carbon deposits within the oil. These factors are a result of the oil breaking down over a long period of time and/or from overheating. An oil analysis can offer insight and help set a baseline regarding the condition of the hydraulic fluid, thus, aiding in assessing the hydraulic oil lifespan. The changing of oil in hydraulic elevators will vary with each system, which is why oil analysis is so imperative. In each scenario, oil will experience different temperatures and pressures, therefore putting a variety of demand on the hydraulic oil, depending on the application. One oil formulation could last anywhere from one thousand hours up to as many as five thousand hours or more depending on the service.
Several oil testing firms attributed contamination and oxidation to be two of the most common reasons an oil change is required in an elevator system. Oil should be changed when it is contaminated (with water, dirt, other foreign contaminants), the viscosity becomes out of spec, or it when it goes beyond its useful service life due to additive depletion, oxidation, sludge and/or varnish build-up. If the viscosity of the oil is poor, the oil may no longer reach all moving parts which will cause greater wear and tear on the hydraulic system. Oil itself does necessarily wear out, it just gets dirty! Sending an oil sample away to a lab for oil analysis is the best way to verify if or how much contamination is present. There are a few tests that many labs will perform in order to determine the remaining service life of the oil. These tests include Total Acid Number, Oxidation by FTIR, anti-oxidation additives by linear sweep voltammetry, viscosity, and RPVOT, which is short for Rotating Pressure Vessel Oxidation Test.
Along with contamination and oxidation, elevator usage is a vital component to consider. One elevator technician credited usage and proper elevator conditions to being the determining factor when it comes to oil changes in hydraulic elevators. An elevator found in a commercial building; say a New York City hotel, for example, operates much more frequently than a residential elevator. Furthermore, another example of high usage hydraulic elevators are the ones located on the Staten Island Ferry. The oil in the elevators found on the Staten Island Ferry has an oil analysis performed quarterly. Due to the fact that the ferry elevators are open to the public and so frequently used, multiple oil tests are needed to ensure everything is functioning properly. Elevators that are used more regularly and have longer hours of operation will most likely require more oil changes throughout their life span. If the oil has been used over a long period of time with high operating temperatures then the oil needs to be changed sooner rather than later. Some lubrication specialist suggested ten years as good approximation for an oil change. If the oil has been used above its recommended operating temperature for a long duration of time, then this time span should be reduced to eight to nine years. Should the correct oil working temperature be used, then the life span could be as long as fifteen years.
Another aspect to consider when determining the integrity and quality of the oil are the elevator’s working conditions, more specifically the machine room temperature and proper ventilation. The elevator machine room temperature should never exceed the manufacture’s requirements. The elevators machine room should also be properly ventilated based on each individual pump unit. Also to be taken into consideration, is the pump unit’s tank. The pump unit’s reservoir should be appropriately sized. Some manufactures have a minimum size reservoir/tank which can lead to premature oil degradation due to excessive friction within oil. If the machine room temperature is incorrect and proper ventilation does not exist, the hydraulic oil can become compromised.
A number of elevators manufacturers suggested oil filtration and changing the oil on a “Condition Based” format. Both of these said methods focus on proactive maintenance. Monitoring the oil and changing it before a problem arises. During the filtration process oil is taken out, the tank cleaned, and then the oil pumped back into the tank through a filter. Condition based oil changes do not focus on numeric years or operating hours, but rather the condition and integrity of the oil itself. In condition based oil changes, oil is changed once it is no longer useable. Through habitual testing by way of oil analysis it can be determined whether or not the oil is serviceable. Studies have shown that condition based oil changes are efficient and highly cost effective.
After communicating with lubricant specialists, technicians, and research teams within the industry, it appears there are numerous aspects to consider when determining the regularity of oil changes concerning hydraulic elevators. As the experts conveyed, the only accurate way to know for sure if the oil has reached its life span is by completing an oil analysis. Changing the hydraulic oil prematurely would be costly for the elevator companies. Conversely, failure to change the oil at all could lead to severe consequences. Recommending that elevator companies complete routine oil analysis tests will help verify the integrity of the oil, thus in turn, making it easier to determine if an oil change is necessary. Oil testing and proactive maintenance have a direct impact on the service life and dependability of the hydraulic elevator. In our daily lives we depend a great deal on vertical transportation to take us from point A to point B. By regularly monitoring the oil’s condition, the service life of the hydraulic equipment can extend far past what it otherwise would have without the testing of oil samples. Oil analysis will ensure that the oil is up to its correct working standard. Properly maintaining hydraulic oil in elevators reduces the risk of damage to the elevator, its equipment, and can reduce unplanned shutdowns. This will also lessen the threat of safety related incidents due to failures. Given that hydraulic oil is such a key component within the hydraulic elevator system it is vital that companies invest in their efforts to guarantee the oil within their equipment is functioning at its full potential.