Sump

A sump (American English and some parts of Canada: oil pan) is a low space that collects any often-undesirable liquids such as water or chemicals. A sump can also be an infiltration basin used to manage surface runoff water and recharge underground aquifers. Sump can also refer to an area in a cave where an underground flow of water exits the cave into the earth.

Examples

One common example of a sump is the lowest point in a basement, into which flows water that seeps in from outside. If this is a regular problem, a sump pump that moves the water outside of the house may be used.

Another example is the oil pan of an engine. The oil is used to lubricate the engine's moving parts and it pools in a reservoir known as its sump, at the bottom of the engine. Use of a sump requires the engine to be mounted slightly higher to make space for it. Often though, oil in the sump can slosh during hard cornering, starving the oil pump. For these reasons, racing and piston aircraft engines are "dry sumped" using scavenge pumps and a swirl tank to separate oil from air, which is also sucked up by the pumps.

Sump (cave)

Sump or siphon is a term used in caving to describe a passage in a cave that is submerged under water. A sump may be static, with no inward or outward flow, or active, with continuous through-flow. Static sumps may also be connected underwater to active stream passage. When short in length, a sump may be called a duck.

Exploration past a sump

Diving

Short sumps may be passed simply by holding one's breath while ducking through the submerged section (for example Sump 1 in Swildon's Hole). This is known as "free diving" and can only be attempted if the sump is known to be short and not technically difficult (e.g. constricted or requiring navigation). Longer and more technically difficult sumps can only be passed by cave diving (as happened repeatedly in the exploration of Krubera Cave).

Draining

When practical, a sump can also be drained using buckets, pumps or siphons. Pumping the water away requires the inward flow of water into the sump to be less than the rate at which the pump empties it, as well as a suitable place to collect the emptied water. Upstream sumps have been successfully emptied using hoses to siphon water out of them, such as at the Sinkhole Dersios during exploration in 2005. The water was sent deeper into the sinkhole and the emptied sumps revealed virgin passage behind them. During a rescue from beyond a downstream sump at Sarkhos Cave in 2002, water was pumped upstream into a dam constructed a few metres above the flooded passage.

Sump (aquarium)

In fishkeeping, a sump is an accessory tank in which mechanical equipment is kept. A remote sump allows for a clutter-free display tank.

It is found in mainly in a reef system. The sump sits below the main tank and is used as a filter, as well as a holding place of unsightly, miscellaneous equipment such as protein skimmers, calcium reactors, heaters and the like. The main advantage of having a sump plumbed into an aquarium is the increase of water in the system, making it more stable and less prone to fluctuations of pH and salinity, and also mitigating the effects of nutrient buildup or the unintentional introduction of foreign substances. In addition, some sumps have a compartment that can be converted into a refugium, helping to filter out excess nutrients such as nitrates.

See also

References