Is it true or false that a holding tank vent line must have a constant rise from the tank to the vent fitting?

A holding tank vent line should indeed maintain a constant rise from the tank to the vent fitting. This design ensures that any liquid or condensed vapor within the line can drain back into the tank, preventing potential blockages and maintaining proper ventilation. A fluctuating or downward slope can lead to situations where liquid collects in the vent line, possibly causing an overflow or pressure buildup, which could result in odors escaping into the vessel.

A constant rise assists in effective venting, ensuring that gases can exit the tank efficiently. It also helps in reducing the risk of clogging, which is particularly important for holding tanks as they deal with waste products. Proper venting is crucial for maintaining the functionality and safety of a marine sanitation device (MSD). This requirement is consistent regardless of tank size or type, underscoring the importance of good design practices in marine systems.