UST System Components & Operations 2 — Questions and Answers
Question 1: What is the primary function of a submersible turbine pump (STP) in an UST system?
- To vent vapors from the tank to the atmosphere
- To transfer product from the underground tank to the dispenser (Correct answer)
- To monitor groundwater beneath the tank
- To pressurize the tank for leak detection
Correct answer: To transfer product from the underground tank to the dispenser
The submersible turbine pump is installed inside the UST and pumps fuel upward through the product line to the dispenser.
Question 2: Which component prevents product from draining back into the UST when the pump shuts off?
- Ball float vent valve
- Shear valve
- Check valve (Correct answer)
- Overfill prevention valve
Correct answer: Check valve
A check valve (foot valve) holds product in the line after the pump stops, preventing siphoning back into the tank.
Question 3: What is the purpose of a hanging hardware assembly at the dispenser?
- To provide structural support for the canopy
- To contain spills during tank filling operations
- To deliver fuel from the dispenser nozzle to the vehicle and allow vapor recovery (Correct answer)
- To monitor fuel inventory in real time
Correct answer: To deliver fuel from the dispenser nozzle to the vehicle and allow vapor recovery
The hanging hardware (hose, breakaway coupling, nozzle) is the customer-facing assembly that dispenses fuel and may incorporate Stage II vapor recovery.
Question 4: A Stage I vapor recovery system is designed to capture vapors during which operation?
- Vehicle refueling
- Tank-to-dispenser pumping
- Delivery of product into the UST (Correct answer)
- Annual tightness testing
Correct answer: Delivery of product into the UST
Stage I vapor recovery captures gasoline vapors displaced from the UST during product delivery from the tanker truck.
Question 5: What does a pressure/vacuum (P/V) vent valve do in a UST vent line?
- Automatically shuts the vent during spills
- Opens only when pressure or vacuum in the tank exceeds set thresholds (Correct answer)
- Continuously vents vapors regardless of tank pressure
- Activates the interstitial space alarm
Correct answer: Opens only when pressure or vacuum in the tank exceeds set thresholds
A P/V valve keeps the vent line normally closed and only opens when tank pressure or vacuum reaches the valve's set point, reducing vapor emissions.
Question 6: Which fitting allows a tank riser pipe to be accessed for product delivery while remaining normally sealed?
- Doghouse fitting
- Sump adapter
- Drop tube
- Kamlock coupling (Correct answer)
Correct answer: Kamlock coupling
A Kamlock (cam-and-groove) coupling provides a quick-connect sealed connection between the delivery hose and the tank fill riser.
Question 7: In a suction-pump UST system, product is pulled to the dispenser by:
- A pump located inside the underground tank
- A pump located at or above grade, usually inside the dispenser (Correct answer)
- Gravity flow through a sloped product line
- Pressurized vapor in the tank headspace
Correct answer: A pump located at or above grade, usually inside the dispenser
A suction system uses a pump mounted in the dispenser or above grade to pull product up from the tank, unlike a pressure system where the STP pushes product.
UST System Components & Operations 2
What is the primary function of a submersible turbine pump (STP) in an UST system?