If a supply tank larger than 10 gallons is provided with an opening in the bottom for use as a burner supply connection or as a drain, the tank shall be pitched toward the opening with a slope of not less than 1/4 inch per foot of length.
34 Pa. Code § 14a.37
This section cited in 34 Pa. Code § 14a.31 (relating to scope); and 34 Pa. Code § 14a.161 (relating to general provisions).