Question

double trapping is a problem because
the water velocity is too great
you need cleanouts on both traps
the water velocity at the second trap is too low
the water velocity at the first trap is too high
the second trap is prone to siphoning
question 34
what is the minimum recommended height of a plumbing vent stack above the roof?
12 inches
30 inches
24 inches
6 inches
1 inch

Explanation:

Double - trapping is a problem because the second trap is prone to siphoning as the flow from the first trap can create negative pressure and draw out the water seal of the second trap. For the plumbing vent stack height, the minimum recommended height above the roof is 12 inches to prevent debris entry and ensure proper venting.

Answer:

1. the second trap is prone to siphoning
2. 12 inches