The decision facing owners of older hydraulic elevators is not an easy one. While failures are rare, the potential for a severe and/or fatal accident exists. In addition, verifying the absence of corrosion on the exterior walls of the cylinder is impossible unless the cylinder is removed from the ground and properly inspected. It is usually inside an underground casing that is as deep as the piston is long. Older cylinders may be virtually as good as new, or badly corroded and nearing failure. The only sure way to confirm the condition of the cylinder, however, is to pull it out of the ground and examine it. But digging up an existing cylinder can be costly and possibly unnecessary.
Generally, the options for owners of older hydraulic systems are as follows:
- Ensure that the hydraulic system is closely monitored for oil leaks. Until recently all governing authorities have permitted older single bottom units to remain in service when properly monitored for oil loss. However, recent code changes in Massachusetts, Maine and Rhode Island now require the addition of safety devices, or the replacement of the cylinders. Their basis is that preventive maintenance alone does not eliminate the risk of cylinder failure.MAINE: Effective January 1, 2004, single bottom hydraulic cylinders will no longer be permitted unless they comply with ASME A17.1 2000 edition and 2002 addenda. This essentially requires a safety bulkhead on cylinders or car safeties to be installed.
MASSACHUSETTS: 524 CMR Requires that hydraulic cylinders buried in the ground installed without a safety bulkhead shall install governor-operated safeties or a piston clamp by January 1, 2004, or that replacement cylinders be provided with schedule 40 PVC liner surrounding it for corrosion protection.
NEW HAMPSHIRE: Effective January 2, 2002, The Department of Labor issued an ADVISORY NOTICE stating that it is the Department’s recommendation that single bottom hydraulic cylinder/jack assemblies be scheduled for replacement as soon as possible. FAILURE TO DETECT AND CORRECT OIL LEAKS IN SINGLE BOTTOM HYDRAULIC CYLINDERS COULD CAUSE DEATH, SERIOUS INJURY AND ENVIRONMENTAL CONTAMINATION.
RHODE ISLAND: Effective January 1, 2004, single bottom hydraulic cylinders will no longer be permitted unless they comply with ASME A17.1 2000 edition and 2002 addenda. This essentially requires a safety bulkhead on cylinders or car safeties to be installed.
- Replace older cylinders with new double bottom safety bulkhead cylinders with additional safeguards from corrosion. Newly designed cylinders offer state-of-the-art systems providing protection from corrosion.
- Fit your existing system with governor-operated safeties or a plunger gripper. As previously noted, traditional governor-operated safeties common to traction elevators are generally not a structurally a viable option. Recent design advances have introduced piston clamp technology as an alternative to conventional safeties. Like traditional safeties this electro-mechanical device detects downward over speeding or unintended downward movement of the car. In this event safety shoes will be activated, closing around the hydraulic piston and bringing the elevator car to a gradual and controlled stop. It is designed to provide protection against over speeding cars and failure of any component of the pressure system, including valves, piping, hoses and the packing head. While the hydraulic elevator plunger gripper safety is designed to prevent the elevator from falling, it does not protect or guarantee the integrity of the cylinder. In the event that underground leaks actually develop, your cylinder must be replaced. This plunger gripper safety is new technology that will require additional annual testing and regular maintenance beyond that currently required. This safety device is not available to all hydraulic elevators at this time. It will only fit hydraulic pistons between 3.5 and 8 inches in diameter, with a maximum weight capacity of between 11,000 to 30,000 pounds (gross load). In many cases it can not be installed due to code required clearances. Considerations for legal applications will vary depending upon the age of equipment, the particular safety features present, and other characteristics of the existing system.
|NO =||Positive Net Impact|
|NO =||Negative Net Impact|
|Comparative Values||New Cylinder||New Safety Device|
|SAFETY OF PASSENGERS||YES||YES|
|PROVEN EFFECTIVE IN MANY INSTALLATIONS||YES||NO|
|PROTECTS THE ENVIRONMENT||YES||NO|
|PROTECTS FROM ADDED/FUTURE COST EXPOSURE||YES||NO|
|GUARANTEED CORROSION PROTECTION||YES||NO|
|PROTECTS CAR FROM DESCENDING AFTER RUPTURE FAILURES||NO||YES|
|PEACE OF MIND||YES||???|
|ADDED MAINTENANCE COSTS||NO||YES|
|OVER 1,000,000 INSTALLED||YES||NO|
|ADDED TESTING REQUIREMENTS||NO||YES|
|RELATIVELY NEW TECHNOLOGY||NO||YES|
|PISTON WALL THICKNESS PROBLEMS||NO||YES|
|POSSIBLE COST ITEMS||NEW CYLINDER||NEW SAFETY DEVICE|
|INSTALL NEW CYLINDER||$15K to $100K||$0|
|INSTALL PISTON SAFETY DEVICE||$0||$15K to 25K|
|PISTON REPLACEMENT||$0||$0 to 10K|
|TESTING COST OF 10 YEARS||$0||$5K|
|ENVIRONMENTAL CLEAN UP COST||$0||$10K TO $200K|
|FUTURE NEW CYLINDER INSTALLATION||$0||$15K to $100K|
|PAY NOW COST||$15K to $100K||$15K to $35K|
|PAY LATER COST||$0||$40K to $340K|
|TOTAL 10 YEAR COST EXPOSURE||$15K to $100K||$40K to $340K|