Hydraulic Elevator Systems Flashcards

During a routine inspection of a hydraulic elevator, the QEI notices that the in-ground cylinder is not equipped with any form of corrosion protection. The elevator was installed in an area with a high water table. Which of the following is the MOST significant risk associated with this finding?

Answer: Catastrophic failure of the cylinder due to electrolysis and corrosion.

Unprotected in-ground hydraulic cylinders are susceptible to corrosion and electrolysis, which can degrade the integrity of the steel. This can lead to an abrupt and catastrophic failure, causing the elevator to fall uncontrollably. This poses a significant safety hazard, far outweighing other potential issues.

According to ASME A17.1, what is the primary purpose of the annual relief valve test on a hydraulic elevator?

Answer: To confirm the valve prevents system pressure from exceeding a safe limit.

The annual relief valve test, as required by ASME A17.1 Section 8.6.5.14.1, is performed to ensure that the relief valve will bypass the full output of the pump and prevent the system pressure from exceeding 150% of the working pressure, thus protecting the system from over-pressurization.

An inspector is examining a newly installed hydraulic elevator in a five-story building. The elevator's rated speed is 150 feet per minute (0.76 m/s). Which type of buffer would be required at the bottom of the hoistway?

Answer: Oil buffers, because the speed is greater than 1.0 m/s.

ASME A17.1 mandates the use of oil buffers for elevators with a rated speed exceeding 1.0 m/s (approximately 200 ft/min). While spring buffers are suitable for lower-speed elevators, oil buffers are required to safely dissipate the kinetic energy of a car traveling at higher speeds, providing a controlled and gradual stop.

A QEI is performing a periodic inspection and finds that the flexible hydraulic hose connecting the power unit to the cylinder line has minor bulging near a fitting, but no visible leaks. What is the appropriate action?

Answer: Require immediate replacement of the flexible hose assembly.

According to ASME A17.1 inspection procedures (referenced in A17.2), any signs of damage or weakness, including bulging or distortion, in a flexible hydraulic hose assembly require it to be replaced. Bulging indicates a failure of the hose's internal reinforcement, and it cannot be safely left in service.

Which of the following components is unique to a roped hydraulic elevator system when compared to a conventional direct-acting hydraulic elevator?

Answer: A governor and safeties.

Roped hydraulic elevators use wire ropes and a sheave attached to the piston to achieve a 2:1 lifting ratio. Because the car is supported by ropes rather than directly by the plunger, they are required to have a governor and car safeties, similar to a traction elevator, to protect against overspeed and free-fall conditions.

During the inspection of a hydraulic elevator machine room, what is the purpose of the device labeled 'Low Oil Protection'?

Answer: To prevent the pump motor from starting if the oil level in the tank is insufficient.

The Low Oil Protection feature is a safety device designed to prevent the pump motor from operating if the hydraulic oil in the reservoir drops below a safe level. This prevents damage to the pump from cavitation (pumping air) and ensures there is sufficient fluid to operate the system safely.