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Diving Mask

 
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A diving mask is an item of diving equipment
Diving equipment

The fundamental item of diving equipment used by divers is the Scuba sets, such as the Aqua-Lung or Rebreather. There are other important pieces of equipment that make diving safer, more convenient or more efficient....
 that allows scuba divers
Scuba diving

SCUBA diving is Underwater diving, or taking part in another activity, while using a scuba set. By carrying a source of breathing gas , the scuba diver is able to stay underwater longer than with the simple breath-holding techniques used in snorkeling and free-diving, and is not hindered by air lines to a remote air source....
, free-divers
Free-diving

Freediving is any of various aquatic activities that share the practice of breath-hold underwater diving. Examples include breathhold spear fishing, freedive photography, apnea competitions and, to a degree, snorkeling....
, and snorkelers
Snorkeling

Snorkeling is the practice of swimming on or through a body of water while equipped with a diving mask, a shaped tube called a snorkel, and usually swimfins....
 to see clearly underwater
Underwater

Underwater is a term describing the realm below the surface of water where the water exists in a natural feature such as an ocean, sea, lake, pond, or river....
. When the human
Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
 eye
Eye

Eyes are Organ that detect light, and send signals along the optic nerve to the visual system and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system....
 is in direct contact with water as opposed to air
AIR

Air is the part of Earth's atmosphere that humans breath and as such Air .Air may also refer to:...
, its normal environment, light
Light

Light, or visible light, is electromagnetic radiation of a wavelength that is Visible spectrum to the human eye , or up to 380?750 nm. In the broader field of physics, light is sometimes used to refer to electromagnetic radiation of all wavelengths, whether visible or not....
 entering the eye is refracted by a different angle and the eye is unable to focus
Focus (optics)

In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge ....
 the light.






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Encyclopedia


Diving Mask
Tauchen1
A diving mask is an item of diving equipment
Diving equipment

The fundamental item of diving equipment used by divers is the Scuba sets, such as the Aqua-Lung or Rebreather. There are other important pieces of equipment that make diving safer, more convenient or more efficient....
 that allows scuba divers
Scuba diving

SCUBA diving is Underwater diving, or taking part in another activity, while using a scuba set. By carrying a source of breathing gas , the scuba diver is able to stay underwater longer than with the simple breath-holding techniques used in snorkeling and free-diving, and is not hindered by air lines to a remote air source....
, free-divers
Free-diving

Freediving is any of various aquatic activities that share the practice of breath-hold underwater diving. Examples include breathhold spear fishing, freedive photography, apnea competitions and, to a degree, snorkeling....
, and snorkelers
Snorkeling

Snorkeling is the practice of swimming on or through a body of water while equipped with a diving mask, a shaped tube called a snorkel, and usually swimfins....
 to see clearly underwater
Underwater

Underwater is a term describing the realm below the surface of water where the water exists in a natural feature such as an ocean, sea, lake, pond, or river....
. When the human
Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
 eye
Eye

Eyes are Organ that detect light, and send signals along the optic nerve to the visual system and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system....
 is in direct contact with water as opposed to air
AIR

Air is the part of Earth's atmosphere that humans breath and as such Air .Air may also refer to:...
, its normal environment, light
Light

Light, or visible light, is electromagnetic radiation of a wavelength that is Visible spectrum to the human eye , or up to 380?750 nm. In the broader field of physics, light is sometimes used to refer to electromagnetic radiation of all wavelengths, whether visible or not....
 entering the eye is refracted by a different angle and the eye is unable to focus
Focus (optics)

In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge ....
 the light. By providing an air space in front of the eyes, light enters normally and the eye is able to focus correctly.

Construction

Diving masks have a durable, tempered
Toughened glass

Toughened or tempered glass is glass that has been processed by controlled heat treatment or chemical treatments to increase its strength compared with normal glass....
 glass
Glass

Glass generally refers to a Hardness, brittle, transparency amorphous solid, such as that used for windows, many Glass Bottles, or eyewear, including, but not limited to, soda-lime glass, borosilicate glass, acrylic glass, sugar glass, Muscovite , or aluminium oxynitride....
 plate in front of the eye
Eye

Eyes are Organ that detect light, and send signals along the optic nerve to the visual system and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system....
s and a "skirt" of rubber
Rubber

Natural rubber is an elastomer?an Elasticity_ hydrocarbon polymer?that was originally derived from a milky colloidal suspension, or latex , found in the sap of some plants....
 or silicone
Silicone

Silicones are largely inert, man-made compounds with a wide variety of forms and uses. Typically heat-resistant, nonstick, and rubberlike, they are commonly used in cookware, medicine, sealants, adhesives, lubricants, and insulation....
 to create a watertight seal
Seal (mechanical)

A mechanical seal is a device which helps join systems or mechanisms together by preventing leakage , containing pressure, or excluding contamination....
 with the diver's face. A strap keeps the mask in position.

Masks that are used at depth must be constructed so that the diver can exhale through the nose
Nose

Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for Respiration in conjunction with the mouth....
 into the mask to prevent the "squeeze
Barotrauma

Barotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding gas or liquid....
" caused by increasing pressure
Pressure

Pressure is the force per unit area applied to an object in a direction surface normal to the surface. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure....
 during descent in water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
.

Some masks have a one-way purge valve under the nose to let water out. The diver simply holds the mask upright and exhales through the nose. While common in snorkeling, this feature is less favored by SCUBA divers because of the possibility of the valve failing at depth and leaving the user no means of clearing his mask. A simple and effective method for clearing a diving mask while underwater is to look down, place a finger on the top of the frame at either side, and slowly look up while exhaling through the nose.

Sometimes masks are sold in conjunction with snorkels and/or swimfins. Low quality snorkelling masks may have a plastic or low-quality glass faceplate, and are not recommended for anything but rare, casual use. Masks that have the snorkel built in are considered hazardous as well.

Divers often test whether a mask is a good fit by placing it on their face, without using the straps, and gently inhaling through their nose. If the mask stays on without any help, and air doesn't get in, then the fit is good.

Use

To prevent a mask from fogging up due to condensation
Condensation

Condensation is the change of the physical state of aggregation of matter from gaseous phase into liquid phase. When the transition happens from the gaseous phase into the solid phase directly, bypassing the liquid phase the change is called Deposition , which is the opposite of sublimation....
 on the glass plate many divers spit
Saliva

Saliva is the watery and usually frothy substance produced in the mouths of humans and most other animals. Saliva is produced in and secreted from the salivary glands....
 into the mask, wipe the spit around the inside of the plate and wash it out with a little water. There are commercial products that can be used as an alternative to the saliva method.

Refraction
Refraction

Refraction is the change in direction of a wave due to a change in its speed. This is most commonly observed when a wave passes from one optical medium to another....
 of light entering the mask makes objects in salt water appear about 34% bigger and 25% nearer when underwater
Underwater

Underwater is a term describing the realm below the surface of water where the water exists in a natural feature such as an ocean, sea, lake, pond, or river....
, as shown in the underwater vision
Underwater vision

Light rays bend when they enter from one medium to another of different Density. The amount of bending is determined by the Refractive index of the two media....
 article. As the diver descends, the water acts as a colour filter
Filter (optics)

Optical filters, generally, belong to one of two categories. The simplest, physically, is the absorptive filter, while the latter category, that of interference or dichroic filters, can be quite complex....
 eliminating the red
Red

Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 625?740 Nanometer....
 end of the visible spectrum
Visible spectrum

The visible spectrum is the portion of the electromagnetic spectrum that is visual perception to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light....
 of the sunlight
Sunlight

Sunlight, in the broad sense, is the total spectroscopy of the electromagnetic radiation given off by the Sun. On Earth, sunlight is Filter ed through the Earth's atmosphere, and the solar radiation is obvious as daylight when the Sun is above the horizon....
 entering the water leaving only the blue
Blue

Blue is a colour, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 440?490 Nanometre....
 end of the spectrum. Depending on the depth and clarity of the water, eventually all sunlight is blocked and the diver has to rely on artificial light source
List of light sources

This is a list of sources of light, including both natural and artificial sources, and both processes and devices....
s to see underwater.

A variety of prescription lenses
Corrective lens

A corrective lens is a lens worn in front of the eye, mainly used to treat myopia, hyperopia, Astigmatism , and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye....
 can be fitted inside the glass plate of the mask to correct some visual problems underwater. Divers may able to use contact lens
Contact lens

A contact lens is a corrective lens, cosmetics, or therapeutic lens usually placed on the cornea of the eye. Modern soft contact lenses were invented by the Czech Republic chemists Otto Wichterle and Drahoslav L?m, who also invented the first gel used for their production....
es inside the mask but they must keep their eyes closed if they remove the mask underwater to avoid losing the lenses. Double-dome masks
Scuba diving

SCUBA diving is Underwater diving, or taking part in another activity, while using a scuba set. By carrying a source of breathing gas , the scuba diver is able to stay underwater longer than with the simple breath-holding techniques used in snorkeling and free-diving, and is not hindered by air lines to a remote air source....
 restore natural sized underwater vision and field of view, while also correcting for a certain range of myopic vision. Mask removal and refitting is a basic skill
Diver training

Diver training is the process of developing skills and building experience in the use of diving equipment and techniques so that the diver is able to diving activities safely and have fun....
 that all divers are taught so that the diver can overcome floods or the mask being dislodged without panic.

When entering the water while wearing the mask, the diver normally needs to place a hand over the mask to disrupt fast water flow during entry. This prevents the mask from becoming dislodged or the glass damaged. Alternatively, a diver can enter the water with the mask off and then put it on or use an entry method such as the "forward roll", where the diver rolls forward with head entering the water first, which does not result in fast water flow over the mask.

It is a good idea to always rinse the mask inside and out with clean, fresh water after each day's use. Dry it off after washing. Do not store the mask in direct sunlight for long periods of time. This will enable the mask to last many years.

Types of diving mask

  • The old type with one big oval pane. In the oldest diving masks this window was an ellipse
    Ellipse

    In mathematics, an ellipse is the apparent shape of a circle viewed obliquely from outside it, as distinct from a hyperbola which is the shape seen from inside....
    .
  • Similar to the previous, but the window is closer to the face, and the window has a big cutout below to fit over the nose, which is kept dry by an expansion of the rubber mask edging.
  • Similar to the previous, but with two windows, one window for each eye, as shown above. This type can have the windows closer to the face than the one-window type and thus contain less space for the diver to have to blow water out of if the mask floods.
  • The double-dome mask. This is a new invention by . Double-dome masks allow a wider field of view and avoid the refraction error in perceived distance and size of objects. Underwater the curved mask windows make the diver's vision effectively more hyperopic / less myopic and the diver must wear special contact lenses to compensate (unless his eyes are myopic to the right amount to compensate exactly for the refraction at the curved mask windows); his vision will go myopic when he puts his head out of water with the contact lenses in.
  • Other optional features:
    • Blowoff valve.
    • Indentations underneath for the diver to put a thumb
      Thumb

      The thumb is the Human_anatomical_terms#Anatomical_directions-most finger of the hand. The English adjective for thumb is pollical....
       and forefinger in to pinch the nose to aid ear clearing
      Ear clearing

      Ear clearing or clearing the ears is any of various maneuvers to equalize the pressure in the middle ear with the outside pressure, by letting air enter along the Eustachian tubes, as this does not always happen automatically when the pressure in the middle ear is lower than the outside pressure....
      .
  • The Data Mask, developed by Oceanic, is an eyes-and-nose diving mask with a built-in LED display which displays various dive and breathing set conditions including the function of a diving computer . It is currently very expensive.


Further reading


Related equipment

There are several specialised types of diving headgear or outerwear:
  • full face diving mask
    Full face diving mask

    A full-face diving mask is a type of diving mask that seals the whole of the diver's face from the water and contains a mouthpiece or demand valve that provides the diver with breathing gas....
     - often worn by working divers who need underwater verbal communication ability.
  • diving helmet
    Diving helmet

    File:Kask-nurka.jpgDiving helmets are worn mainly by professional diving engaged in surface supplied diving, though many models can be adapted for use with SCUBA equipment....
     - often worn by divers using surface supplied diving
    Surface supplied diving

    Surface supplied diving refers to diving activities using equipment supplied with breathing gas using an Umbilical cord#Other uses for the term "umbilical cord" from the surface, often from a diving support vessel but possibly, indirectly via a diving chamber....
     equipment.
  • hard hat - part of the old fashioned standard diving dress
    Standard diving dress

    A standard diving dress consists of a metallic diving helmet, an airline or air hose from a surface supplied diving air diving pump, a canvas diving suit, diving knife and boots....
    .
  • fluid filled mask - the need to equilibrate the internal pressure in the mask by exhaling air through the nose reduces the freediver capacity to dive deep. Masks or swimming goggles with high power lenses (40-200 diopters) have been developed in this view: they are filled with water or saline fluid ( fluid goggles).


External links

  • - From antiquity to the present.