Recently, I bit down a bit too hard on a candy cane and I felt a strange sensation. My mouth was suddenly filled with a substance that was more like small gravel or sand than a candy cane. I knew that gravel wasn’t on the list of ingredients, which meant something I dreaded much more: One of my molars was broken and the pieces filled my mouth. Ouch!
I’m obsessive about my brushing and flossing, to the point of pride. But, little did I know, deep in the recesses of my #18 molar, insidious forces were at work. Painlessly and silently, tooth decay destroyed my dental pride from the inside out, and made a dent in my bank account.
A similar story can be told about elevators. They can look nice and shiny, with highly polished stainless steel hall calls, gleaming handrails and fancy glass interiors. They can be well cared for and brushed to a brilliant sheen, but the mechanisms that make them go up and down maybe rotting from the inside out, without anyone being the wiser. This is particularly true of older, in-ground jacks of hydraulic elevators because part of the elevator system is in the ground. And far below the surface of the earth, they could be rotting with corrosion and rust.
Pre-Nixon administration hydraulic jacks were made with a single metal bottom plate. With the jack exposed to the water in the ground, over time it can rust. When it rusts all the way through the wall, the hydraulic oil begins to leak out. If the jack loses oil all at once, the elevator car could fall.
Today’s jacks have a “double bottom” with the “second bottom” consisting of a bulkhead and orifice the slow any leakage and prevent a complete, sudden emptying of the jack. In addition, the jack is contained in a sealed PVC liner, so there is no contact between the jack and elements that could rust it.
Should you worry about this if you are a building owner? If you have a very old hydraulic elevator with an in ground jack, it is a concern. If you have not had quality routine maintenance, it is a concern as well. One of the telltale signs is that your oil level drops over time but it’s not visible in the pit buckets, which contain oil that leaks through the packing. If oil is disappearing without a trace, it’s likely going into the ground.
Another way to detect a leak is during annual inspections, which are required in most jurisdictions, and include a hydraulic system pressure test. During this test, the hydraulic system of the elevator is tested to the maximum pressure the system can maintain. This maximum pressure is referred to as the relief pressure. The relief pressure can be up to 150% of the working pressure as per many state codes.
The working pressure is the pressure in the hydraulic system running at full speed and full weight capacity. During this annual pressure test, old and weak jacks plagued by rust and corrosion are susceptible to rupture. When it does, be glad it occurred during a test and not when passengers where along for the ride. It is always better to have a failure during a safety controlled test.
Just as I found out with my tooth, elevator repair can be expensive if it requires an entire jack replacement. However, because safety is paramount, if a problem exists it must be discovered and repaired sooner rather than later. The bottom line, is despite my desire not to have dental work done, it was needed. And if your aging jack is leaking, it’s much better to find out before the leak gets dangerous. Then you can replace it on your time schedule instead of performing emergency surgery.