A completely full water storage tank is being hydrostatically tested to 200 psig using a positive displacement pump (PDP) with a smooth and constant discharge flow rate of 8 gpm.
The tank is protected by a relief valve and a safety valve that both discharge to the atmosphere.
The valves have the following characteristics:
- The relief valve opening setpoint is 220 psig with an accumulation of 5 percent.
- The safety valve opening setpoint is 260 psig with a blowdown of 5 percent.
- Both valves have a maximum discharge flow rate of 6 gpm.
The PDP is inadvertently left running when tank pressure reaches 200 psig.
After a few minutes with the PDP still running, the relief valve will be discharging a flow rate of approximately __________; and the safety valve will be __________.
A. 2 gpm; partially open
B. 6 gpm; partially open
C. 2 gpm; cycling between fully open and fully closed
D. 6 gpm; cycling between fully open and fully closed
Show Answer
Answer: D
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