What is "demister"

n. 1 A part of the ventilation system in motor cars that blows hot, dry air against the inside of a windscreen to prevent, or remove condensation 2 Any of various devices that removes droplets of water from air

n. heater that removes mist from the windshield of a car

A demister is a substance applied to transparent surfaces to stop them from becoming fogged with mist deposit, often referred to as fog. Scuba divers often spit into their masks and then wash the surface quickly with water to prevent mist buildup that can impair vision. Several products are commercially available such as Sea Drops that are generally more effective. New masks lenses still have silicone on them from the manufacturing process, so it is recommended to clean the lenses with toothpaste, rinse the mask and then apply a demister solution.

Category:Diving equipment

Demister may refer to:

• Demister (SCUBA), a product used to clear a scuba mask of "fog"
• Demister (vapor), a device that removes entrained liquid droplets from a gas stream
• Window demister, a heating device fitted to rear windows of modern automobiles to clear the window of "fog" and known in the U.S. as a defogger

A demister is a device often fitted to vapor-liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream. Demisters may be a mesh type coalescer, vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream.

Demisters can reduce the residence time required to separate a given liquid droplet size by reducing the volume and associated cost of separator equipment. Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high (e.g., high pressure systems) or where space or weight savings are advantageous.

For example, in the process of brine desalination on marine vessels, brine is flash heated into vapor. In flashing, vapor carries over droplets of brine which have to be separated before condensing, otherwise the distillate vapor would be contaminated with salt. This is the role of the demister. Demisted vapor condenses on tubes in the desalination plant, and product water is collected in the distillate tray.