AskDefine | Define millrace

Dictionary Definition

millrace n : a channel for the water current that turns a millwheel [syn: millrun]

User Contributed Dictionary



  1. The stream of water that drives a water wheel.
  2. The channel through which this stream runs.

Extensive Definition

The terms "sluice gate" and "slide gate" are used interchangeably in the water/wastewater control industry.
A sluice is a water channel that is controlled at its head by a gate. For example, a millrace is a sluice that channels water toward a water mill.
A sluice gate is traditionally a wooden or metal plate which slides in grooves in the sides of the channel. Sluice gates are commonly used to control water levels and flow rates in rivers and canals. They are also used in wastewater treatment plants and to recover minerals in mining operations.
A sluice/slide gate is a double-faced valve consisting of an open frame and a slide. Examples of where this type of valve is used include controlling flow (water and wastewater) at openings in tank walls and at ends of pipes. The term "slide gate" has been adopted for use by series of standards (C561, American Water Works Association) C561 is the standard for Fabricated Stainless Steel Slide (Sluice) Gates. This standard was approved in January of 2004.
This standard describes fabricated stainless steel sluice/slide gates with full aperture closure, designed for either seating or unseating head, or both, in ordinary water supply service. The stainless steel gates have non-metallic seat/seals, which may be of self-adjusting design. Some sluice gate manufacturers use ultra high molecular weight(UHMW) polyethelene seat/seals, to allow ease of movement and eliminate friction.


Raising a sluice gate allows water to flow under it. (The term sluice gate refers to any gate that operates by allowing water to flow under it.) When a sluice gate is fully lowered, water sometimes spills over the top, in which case the gate operates as a weir.
Usually a mechanism drives the sluice gate up or down. This may be a simple, hand-operated, worm drive or rack and pinion drive, or it may be electrically or hydraulically powered.

Types of sluice gates

; Vertical rising sluice gate : A plate sliding in the vertical direction, controlled by machinery.; Rising sector sluice gate : Also a part of a cylindrical surface, which rests at the bottom of the channel and rises by rotating around its centre.The gates of a Guillotine lock work in a way similar to a sluice gate, but most canal lock gates are hinged to swing like doors.

Regional names for sluice gates

In the Somerset Levels, sluice gates are known as clyse or clyce. Most of the inhabitants of Guyana refer to sluices as kokers.

Logging Sluices

In the mountains of New England, sluices were used to transport logs from steep hillsides to downslope sawmill ponds or yarding areas. 19th century logging was traditionally a winter activity for men who spent summers working on farms. Water was applied to logging sluices every night so a fresh coating of slippery ice would reduce friction of logs placed in the sluice the following morning.

Placer Mining applications

Sluiceboxes are often used in the recovery of black sands, gold, and other minerals from placer deposits during placer mining operations. They may be small-scale, as used in prospecting, or much larger as in commercial operations, where the material is first screened using a trommel or screening plant. Typically, the sluices have transverse riffles over a carpet which trap the heavy minerals, gemstones, and other valuable minerals. The result is a concentrate.


Further reading

  • The Maine Scenic Route
  • The Maine Two-Footers
  • Ride the Sandy River
  • Two Feet Between the Rails (Volume 1 - The Early Years)

See also

millrace in Czech: Stavidlo
millrace in French: Sluice
millrace in Dutch: Sluis (kunstwerk)
millrace in Japanese: 水門
millrace in Swedish: Sluss
Privacy Policy, About Us, Terms and Conditions, Contact Us
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2
Material from Wikipedia, Wiktionary, Dict
Valid HTML 4.01 Strict, Valid CSS Level 2.1