ETC Mechanical Systems & Equipment Flashcards
6 cards from real ETC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 ETC Mechanical Systems & Equipment flashcards as text
What is the purpose of an expansion joint in a piping system?
Answer: To allow for thermal expansion and contraction without stressing pipe or equipment
Expansion joints absorb dimensional changes caused by temperature variations, preventing thermal stress and potential failure in piping systems.
What does NPSH represent for a centrifugal pump?
Answer: The pressure available at the pump inlet above vapor pressure, preventing cavitation
NPSH is the difference between the absolute pressure at the pump suction and the vapor pressure of the liquid, determining whether cavitation will occur.
What is the purpose of a pressure reducing valve in a water distribution system?
Answer: To reduce upstream pressure to a lower regulated downstream pressure
A PRV reduces high upstream water pressure to a safe, regulated level suitable for building fixtures and piping systems.
What is the refrigeration cycle's primary purpose in an air conditioning system?
Answer: To transfer heat from the indoor space to the outdoor environment using a refrigerant
The refrigeration cycle uses a refrigerant to absorb heat inside the building and reject it outside, cooling the interior space.
What does brake horsepower measure for a pump or motor?
Answer: The actual power delivered to the pump shaft, accounting for mechanical losses
Brake horsepower is the actual mechanical power delivered at the shaft, which is less than motor nameplate power due to mechanical inefficiencies.
What is the purpose of a variable air volume (VAV) box in an HVAC system?
Answer: To modulate airflow to individual zones based on thermostat demand
A VAV box regulates the volume of conditioned air supplied to a zone by varying the damper position in response to the zone thermostat setpoint.