In-ground hydraulic elevators have been in use for more than 70 years, with numerous design, engineering, and code changes occurring over time to improve reliability and safety. Although mechanically simple, hydraulic elevators are susceptible to an unseen, corrosive condition called electrolysis that represents potential liability and significant repair costs to building owners in the event of a breach of the underground hydraulic cylinder.
History of Hydraulics
Before 1972, hydraulic cylinders were typically manufactured with a single, flat bottom. This single bottom did not provide adequate safety in the event the breach occurred at the bottom. As a result, the code was revised in 1972 to require that cylinders be manufactured with a “double” bottom, with the upper designed as a safety bulkhead. Although this change addressed a breach at the bottom of the cylinder, it is still possible for the cylinder to fail due to corrosive activity anywhere along its length.
What This Means for You
It’s important to evaluate your existing system to determine what, if any, corrective actions are required. A competent, qualified consultant should be involved to determine available options and to recommend appropriate action.
As a beginning, insist upon immediate attention (and written response) from your maintenance provider regarding these questions:
1. When was the system manufactured? (Particularly important if the building was constructed prior to 1972 or during the transition period up through 1973.)
2. Do you know, or do records indicate, if the hydraulic jack assembly was installed inside an outer protective casing or included any type of electrolysis protection?
3. Have you detected an oil leak in the system? If so, have you identified the location of the oil leak?
4. What are your legal obligations?
5. If you have detected an oil leak in the system and the source is not readily apparent, then:
a. What steps will you take in order to identify the location of the leak?
b. When will this be accomplished?
c. What are the cost implications?
d. How long will elevator service be interrupted?
6. When did you last perform routine and periodic system tests required by the National Elevator Code ASME A17.1, or other jurisdiction?
What Are Your Obligations?
The most recent code change occurred in 2002, and is directed specifically at elevators manufactured prior to 1972 with a “single bottom” cylinder. Owners with “single bottom” cylinder elevators must complete one of two prescribed courses of action. Either 1) replace the cylinder with a double cylinder or a cylinder with a safety bulkhead protected from corrosion by an approved method; or 2) install an approved device on the existing system to protect against unintended car movement as a result of uncontrolled fluid loss.
The National Elevator Code requires hydraulic systems to be pressure-tested on an annual basis. More frequent monitoring and testing (i.e., monthly, quarterly, etc.) provides consistent information on the status of the system, and in the event of an incident, would demonstrate that proactive measures were taken above and beyond minimum requirements.
Testing may accelerate cylinder failure if it’s already in a weakened condition. Remember, the day after a test reveals no leak, a leak can develop. Also be aware: Your maintenance provider may expect compensation for this additional testing. Require written confirmation of these tests, and of any additional testing you authorize that goes beyond code requirements.
Jay A. Popp is vice president of Analysis and Technical Standards at Littleton, CO-based Lerch Bates & Associates (www.lerchbates.com).