Una máscara de buceo (también media máscara , la máscara de buceo o máscara de buceo ) es un elemento de equipo de buceo que permite bajo el agua buceadores , incluyendo los buceadores , libres buzos y buceadores , para ver claramente bajo el agua . [1] [2] Los buzos que se suministran desde la superficie usualmente usan una máscara facial completa o un casco de buceo , pero en algunos sistemas se puede usar la media máscara. [2] Cuando el ojo humano está en contacto directo con el agua en lugar del aire., en su entorno normal, la luz que entra en el ojo se refracta en un ángulo diferente y el ojo no puede enfocar la luz en la retina. Al proporcionar un espacio de aire frente a los ojos, el ojo puede enfocar casi normalmente. La forma del espacio de aire en la máscara afecta ligeramente la capacidad de enfoque. Se pueden colocar lentes correctivos en la superficie interior de la ventana o se pueden usar lentes de contacto dentro de la máscara para permitir una visión normal a las personas con defectos de enfoque.
Otros nombres |
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Usos | Proporciona una visión subacuática clara para los buceadores. |
Artículos relacionados | Máscara de cara completa , Gafas de natación |
Cuando el buceador desciende, la presión ambiente se eleva, y se hace necesario para igualar la presión dentro de la máscara con la presión ambiental externa para evitar el barotrauma conocido como squeeze máscara , Esto se realiza permitiendo que el aire suficiente fluya hacia fuera a través de la nariz hasta el máscara para aliviar la diferencia de presión. Esto requiere que la nariz esté incluida en el espacio aéreo de la máscara. La ecualización durante el ascenso es automática ya que el exceso de aire dentro de la máscara se escapa fácilmente más allá del sello.
Hay disponible una amplia gama de formas de ventana gráfica y volúmenes internos, y cada diseño generalmente se ajustará mejor a algunas formas de cara que a otras. Un buen ajuste cómodo y un sello confiable alrededor de los bordes del faldón de goma es importante para el correcto funcionamiento de la máscara.
Se sabe que existen nueve estándares nacionales e internacionales relacionados con las máscaras de buceo: estándar británico BS 4532: 1969 (enmendado en 1977); [3] Norma GOST 20568: 1975 de la URSS y la CEI (activa); [4] Norma alemana DIN 7877: 1980; [5] Norma de la industria polaca BN-82 / 8444-17.01 (activa). [6] Norma nacional estadounidense ANSI Z87.11: 1985 (activa); [7] Norma austriaca ÖNORM S 4225: 1988; [8] Norma nacional china CNS 12497: 1989 (activa); [9] Norma nacional china CNS 12498: 1989 (activa); [10] y la norma europea EN 16805: 2015 (activa). [11]
Función
Los rayos de luz se desvían cuando viajan de un medio a otro; la cantidad de flexión está determinada por los índices de refracción de los dos medios. Si un medio tiene una forma curva particular, funciona como una lente . La córnea , los humores y el cristalino del ojo forman juntos un cristalino que enfoca las imágenes en la retina . Nuestros ojos están adaptados para ver en el aire. Sin embargo, el agua tiene aproximadamente el mismo índice de refracción que la córnea (ambos alrededor de 1,33), por lo que la inmersión elimina eficazmente las propiedades de enfoque de la córnea. Cuando nuestros ojos están en el agua, en lugar de enfocar las imágenes en la retina, ahora las enfocan muy por detrás de la retina, lo que resulta en una imagen extremadamente borrosa por hipermetropía . [12]
Al usar una máscara de buceo plana, los humanos pueden ver claramente debajo del agua. [12] [13] [14] La ventana plana de la máscara de buceo separa los ojos del agua circundante por una capa de aire. Los rayos de luz que entran desde el agua a la ventana plana paralela cambian mínimamente su dirección dentro del propio material de la ventana. [12] Pero cuando estos rayos salen por la ventana hacia el espacio de aire entre la ventana plana y el ojo, la refracción es bastante notable. Las trayectorias de la vista se refractan (se doblan) de una manera similar a la de los peces que se encuentran en un acuario. Los filtros polarizadores lineales reducen la visibilidad bajo el agua al limitar la luz ambiental y atenuar las fuentes de luz artificial. [15]
La refracción de la luz que entra en la máscara hace que los objetos parezcan un 34% más grandes y un 25% más cercanos cuando están bajo el agua . También se notan la distorsión en acerico y la aberración cromática lateral . A medida que el buceador desciende en agua limpia, el agua actúa como un filtro de color eliminando el extremo rojo del espectro visible de la luz solar que ingresa al agua dejando solo el extremo azul del espectro. Dependiendo de la profundidad y claridad del agua, eventualmente toda la luz solar se bloquea y el buceador tiene que depender de fuentes de luz artificial para ver bajo el agua. [12] [16]
Construcción
Hay dos categorías básicas de máscara de buceo: la media máscara cubre los ojos y la nariz, y la máscara completa cubre los ojos, la nariz y la boca y, por lo tanto, incluye una parte del aparato respiratorio. La media máscara se describe aquí. [17] : 4-17
Las máscaras de buceo pueden tener una sola placa frontal de vidrio templado duradero o dos lentes frente a los ojos . Estos pueden estar soportados por un marco de plástico o metal relativamente rígido, o pueden estar unidos permanentemente al borde del faldón, en una construcción conocida como "sin marco". En el caso de las máscaras de apnea, que deben tener un volumen interno bajo para minimizar la cantidad de respiración necesaria para igualar el cambio de presión que ocurre con la profundidad, las lentes pueden estar hechas de plástico de policarbonato . Por lo general, hay un "faldón" de caucho sintético o elastómero de silicona para sostener la montura y las lentes y crear un sello hermético con la cara del buceador. [1] [17] : 4-17 El material del faldón puede ser casi transparente, translúcido u opaco. Un faldón casi transparente proporciona una mayor visión periférica, aunque algo distorsionada, y puede reducir la sensación de claustrofobia en algunos buceadores, pero en algunos casos la luz que entra por los costados puede provocar reflejos internos que distraigan. El faldón también encierra la nariz, generalmente por medio de un bolsillo nasal, de modo que se pueda exhalar aire a través de la nariz hacia la máscara para igualar la presión interna durante el descenso y así evitar un posible barotrauma de la zona cerrada de la cara. [18] La sección de la máscara que cubre la nariz debe permitir al usuario bloquear las fosas nasales mientras se iguala la presión en el oído medio. Todas las máscaras de buceo tienen medios para mantenerlas en posición, generalmente una correa de elastómero de material similar a la falda, [1] pero ocasionalmente se usa una almohadilla de neopreno expandido con correas de velcro. Las correas de la máscara suelen ser más anchas en la parte posterior o se dividen en una correa superior e inferior en la parte posterior de la cabeza para mayor estabilidad y comodidad. [17] : 4-17
Algunas mascarillas tenían una válvula de purga unidireccional debajo de la nariz para dejar salir el agua, pero esto ya no es común porque no eran necesarias ni confiables y, a menudo, tenían fugas. [17] : 4-17
Corrección visual
Diving masks can be fitted with prescription lenses for divers needing optical correction to improve vision.[19] Corrective lenses are ground flat on one side and optically cemented to the inside face of the mask lens. This provides the same amount of correction above and below the surface of the water. Bifocal lenses are also available for this application. Some masks are made with removable lenses, and a range of standard corrective lenses are available which can be fitted. Plastic self-adhesive lenses that can be applied to the inside of the mask may fall off if the mask is flooded for a significant period. Contact lenses may be worn under a mask or helmet, but there is some risk of losing them if the mask is dislodged in turbulent water.[16][20]
Encajar
A mask is considered to fit well when it seals comfortably and effectively all round the skirt, and provides a good field of vision, without pressing on the nose or forehead while in use underwater. A low internal volume is considered desirable by freedivers, as less breath is wasted to equalise, and by scuba divers, as there is less tendency to press up under the nose due to buoyancy, which becomes uncomfortable quite quickly.[21]
Divers may 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 this indicates that no air is being drawn in and that the skirt is in sufficient contact with the facial skin all the way round the mask. Optimum sealing requires that hair strands do not cross under the edge of the seal, as they can provide a path for water to leak into the mask. This is more a problem with the forehead hairline than with lower facial hair, as water from the top tends to run into the eyes, while water pooling at the bottom is easily purged by exhaling a small volume of air through the nose. Most bearded divers learn to manage the slight leakage without difficulty, inconvenience, or greasing the moustache. Other factors affecting a comfortable fit are sufficient space for the nose in the nose pocket, no contact between the rigid mask frame and the bridge of the nose, and no excessive pressure on the forehead. There should also be sufficient space between the mask lenses and the face that the eyelashes do not contact the glass noticeably when blinking.[22]
Usar
The strap can be adjusted to suit the diver's head. Too loose may not provide an effective seal and the mask may dislodge easily, and too tight may result in discomfort or pain. Correct positioning of the strap around the back of the head will reduce the risk of dislodging and facilitate clearing.[23]
When entering the water while wearing the mask, the diver may need to manually prevent water impact from dislodging or knocking off the mask. Alternatively, a diver can enter the water with the mask off and then put it on or use an entry method which does not result in fast water flow over the mask. Wearing the mask pushed up onto the forehead while out of the water or on the surface increases the risk of the mask falling or being knocked off.[23]
To prevent a mask from fogging up due to condensation on the glass many divers spit into the dry mask before use, spread the saliva around the inside of the plate and rinse it out with a little water. The saliva residue allows condensation to wet the glass and form a continuous film, rather than form droplets. There are commercial products that can be used as an alternative to the saliva method, some of which are more effective and last longer.[24]
Standard maintenance is to rinse inside and out with clean, fresh water after each day's use, and allow to dry out of direct sunlight before storage. Ultraviolet light degrades the synthetic materials of the skirt and frame. A well-maintained mask should last for several years. The strap is the most stressed component and is often the first part to fail, but can usually be replaced. Inspection of the strap for cracks and tears before use can reduce the risk of failure during a dive.[23]:56
Mask removal and refitting underwater and clearing are basic skills that all divers must learn so that they can deal with flooding and leaks or the mask being dislodged without panic.[21]
Mask clearing
It is quite common for water to leak into the mask, which can be annoying, or interfere with clear vision, and the diver needs to be able to get rid of the water quickly and effectively. Reasons for the leakage include poor fit or fitting, leaking via head or facial hair, movement of the facial muscles causing temporary leaks, or impact of external objects against the mask, which may distort it temporarily, or move it so that it leaks, or in extreme cases dislodge it entirely from the diver's head.[17]:6-13
The methods of clearing differ between the half mask, which covers the eyes and nose, and the full-face mask, which also covers the mouth. If the mask has a purge valve and the strap tension is correct, the diver holds the head so that the valve is at the lowest point and exhales through the nose. If the mask is a good fit on the diver's face and the strap is correctly placed, exhaling through the nose will usually drive water out along the bottom edge of the skirt. It may be necessary to press the upper part of the mask against the face to improve the seal if the diver is rolled to one side. If the fit is not perfect, or the strap is too low, contact pressure of the top edge against the forehead may be insufficient to maintain a seal when the head is upright.[17]:6-13
Equalizing
The pressure changes during ascent and descent may affect gas spaces in the diver and diving equipment. A change in pressure will cause a pressure difference between the gas space and environment which will cause the gas to expand or compress if that is possible, and constraining the gas from expanding or compressing to balance the pressure may cause damage to the surrounding material or tissues by over-expansion or crushing. Some gas spaces, such as the mask, will automatically release excess gas as it expands during ascent, but have to be equalized during compression of descent.[21]
Equalising of the mask is an essential skill for any form of diving. Goggles that do not cover the nose can not be equalised and are unsuitable for diving. The mask is equalised by exhaling sufficient air through the nose to provide a balanced internal pressure. Any excess will simply leak out around the skirt. Equalising (or clearing) the ears is necessary to prevent barotrauma to the middle and inner ear. Some divers need to pinch the nostrils closed as part of their equalisation technique, and this must be allowed for in the design of the mask skirt.[21]
Tipos de máscara de buceo
Older diving mask with one big window
Disassembled single-window, low-volume dive mask
A two-window, soft-silicone dive mask without purge valve
A HydroOptix Double-Dome mask
Mask with bifocal lenses for reading instruments
A diving mask showing the retaining strap
A twin-lens, low-volume diving mask, Aqua Lung (Technisub) Sphera, with wide peripheral view of the type favoured by many Underwater Hockey players.
Early model diving masks came with a single pane of glass or transparent plastic, whose shape was usually elliptical, sometimes circular or even rectangular or triangular with rounded corners.[25] These masks have indentations in the skirt at the bottom on either side of the nose, into which the diver can insert a thumb and forefinger to pinch the nose, when performing a Valsalva maneuver to clear their ears. This design was improved by bringing the window closer to the face, reducing the volume of air inside the mask, thus making mask clearing easier. The window has a cutout to fit around the nose, which is covered by the rubber or silicone material of the skirt. This facilitates pinching the nose when ear-clearing.[21]
A further development is the mask with two windows, one for each eye. It can have the windows closer to the face than the one-window type, and therefore contain even less internal volume for the diver to clear or equalise. These types are often called a "low-volume mask".[21] Participants in the sport of underwater hockey are required to use twin-lens masks of this type for their own safety - the sport uses a heavy lead puck similar to an ice hockey puck, nan but skilful players can flick the puck considerable height off the bottom when making passes which leads to the possibility of accidental puck contact with other players. Should a puck hit the lens of a single-lens mask there is a good chance it will break the glass and pass through the aperture to hit the face and eyes, but with a twin-lens mask though the glass may break the frame will prevent the passage of the puck any further.[26]
Recent innovations have produced more complex designs, intended to provide extra features:
- The double-dome mask. This was invented by HydroOptix. 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, or 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). The diver's vision will become myopic when he puts his head out of water with the contact lenses in.[27]
- The "Data Mask", or integrated diver display mask, developed by Oceanic, is a half mask with a built-in LCD head up display which displays various dive and breathing set conditions including the function of a diving computer, depth and tank pressures.[28]
Equipos relacionados
There are several specialised types of diving headgear or outerwear:
- full face diving mask - often worn by working divers who need underwater verbal communication ability.
- Lightweight diving helmet - usually worn by divers using surface supplied diving equipment.
- Copper hat - part of the old fashioned standard diving dress.
- 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.[29]
Ver también
- Underwater vision – Effects of the underwater environment on (human) vision
- Human factors in diving equipment design – Influence of the interaction between the user and the equipment on design
Referencias
- ^ a b c Professional Association of Diving Instructors (2008). Encyclopedia of Recreational Diving (3rd ed.). Rancho Santa Margarita, CA: PADI. ISBN 978-1-878663-01-6.
- ^ a b NOAA Diving Program (U.S.) (28 Feb 2001). Joiner, James T. (ed.). NOAA Diving Manual, Diving for Science and Technology (4th ed.). Silver Spring, Maryland: National Oceanic and Atmospheric Administration, Office of Oceanic and Atmospheric Research, National Undersea Research Program. ISBN 978-0-941332-70-5. CD-ROM prepared and distributed by the National Technical Information Service (NTIS)in partnership with NOAA and Best Publishing Company
- ^ Specification for snorkels and face masks. Amendment Slip No. 1 to BS 4532:1969 Snorkels and face masks, 30 December 1977 (Technical report). London: British Standards Institution. 1969.
- ^ GOST 20568-75. Маски резиновые для плавания под водой. Общие технические условие. Rubber masks for submarine swimming. General specifications. Retrieved on 8 March 2019 at https://pdf.standartgost.ru/catalog/Data2/1/4294832/4294832859.pdf.
- ^ Deutsches Institut für Normung: DIN 7877: Tauch-Zubehör. Tauchbrillen. Sicherheitstechnische Anforderungen und Prüfung. Diving accessories for skin divers. Diver’s masks. Requirements and testing, Berlin/Cologne: Beuth Verlag, 1980.
- ^ Ireneusz Wasielewski/Instytut Przemysłu Gumowego STOMIL (Łódź) (1982) BN-82/8444-17.01. Gumowy sprzęt pływacki - Maski pływackie. Warsaw: Wydawnictwa Normalizacyjne „Alfa”. Document retrieved on 10 January 2020 at http://bc.pollub.pl/publication/2949.
- ^ American National Standards Institute (1985). Underwater Safety. Recreational Skin and Scuba Diving. Lenses for Masks. ANSI Z87.11:1985 (Technical report). New York: American National Standards Institute.
- ^ Austrian Standards Institute (1988). Tauchmasken (Tauchbrillen); Sicherheitstechnische Anforderungen, Prüfung, Normkennzeichnung. Diving accessories; divers' masks; safety requirements, testing, marking of conformity. ÖNORM S 4225 (Technical report). Vienna: Austrian Standards Institute.
- ^ Bureau of Standards, Metrology and Inspection. 潛水鏡. Diving mask. CNS 12497 (Technical report). Bureau of Standards, Metrology and Inspection, Republic of China.CS1 maint: uses authors parameter (link) Preview available at https://www.cnsonline.com.tw/.
- ^ Bureau of Standards, Metrology and Inspection. 潛水鏡檢驗法. Method of test for diving mask. CNS 12498 (Technical report). Bureau of Standards, Metrology and Inspection, Republic of China.CS1 maint: uses authors parameter (link) Preview available at https://www.cnsonline.com.tw/.
- ^ British Standards Institution (2015). Diving equipment. Diving mask. Requirements and test methods. BS EN 16805 (Technical report). London: British Standards Institution.CS1 maint: uses authors parameter (link)
- ^ a b c d Adolfson J and Berhage, T (1974). Perception and Performance Under Water. John Wiley & Sons. ISBN 0-471-00900-8.
- ^ Luria, SM; Kinney, J. A. (March 1970). "Underwater vision". Science. 167 (3924): 1454–61. doi:10.1126/science.167.3924.1454. PMID 5415277.
- ^ Weltman, G.; Christianson, R. A.; Egstrom, G. H. (October 1965). "Visual fields of the scuba diver". Human Factors. 7 (5): 423–30. doi:10.1177/001872086500700502. PMID 5882204.
- ^ Luria, S. M.; Kinney, J. A. (December 1974). "Linear polarizing filters and underwater vision". Undersea Biomedical Research. 1 (4): 371–8. PMID 4469103. Archived from the original on 2009-09-14. Retrieved 2008-07-06.
- ^ a b Sawatzky, David (1 November 2015). "Corrective Dive Masks". Columns, Diving Medicine. Diver magazine. Retrieved 10 December 2016.
- ^ a b c d e f NOAA Diving Program (U.S.) (December 1979). Miller, James W. (ed.). NOAA Diving Manual, Diving for Science and Technology (2nd ed.). Silver Spring, Maryland: US Department of Commerce: National Oceanic and Atmospheric Administration, Office of Ocean Engineering.
- ^ Butler, FK; Gurney, N (2001). "Orbital hemorrhage following face-mask barotrauma". Undersea and Hyperbaric Medicine. Undersea and Hyperbaric Medical Society. 28 (1): 31–4. PMID 11732882. Retrieved 2008-07-06.
- ^ Bennett QM (June 2008). "New thoughts on the correction of presbyopia for divers". Diving Hyperb Med. 38 (2): 163–4. PMID 22692711. Retrieved 2013-04-19.
- ^ Lonne, Torben. "Diving With Contact Lenses". Articles. DIVE.in. Retrieved 10 December 2016.
- ^ a b c d e f Hanekom, Paul; Truter, Pieter (February 2007). Diver Training Handbook (3rd ed.). Cape Town, South Africa: Research Diving Unit, University of Cape Town.
- ^ Roberts, Fred M. (1963). "2 Basic equipment". Basic Scuba: Self contained underwater breathing apparatus: Its operation, maintenance and use (2nd ed.). New York: Van Nostrand Reinholdt.
- ^ a b c British Sub Aqua Club. Sport Diving. London: Stanley Paul. ISBN 0-09-163831-3.
- ^ Nelson, Brenda (28 March 2017). "Tips for Preventing Mask Fog". PADI Blog. Professional Association of Diving Instructors. Retrieved 24 April 2017.
- ^ Jack McKenney: "Up to our snorkels in masks", Skin Diver (June 1973), pp. 18-21.
- ^ uwhberlin (2 February 2015). "Gear needed for underwater hockey". Underwater Hockey in Berlin. Retrieved 4 May 2017.
- ^ "Discover What You Have Been Missing!". HydroOptix. 30 April 2009. Retrieved 2009-09-23.
- ^ "DataMask HUD". Oceanic Worldwide. 2007. Archived from the original on 2004-12-06. Retrieved 2009-09-23.
- ^ "Fluid Goggles". Liquivision Products. 2009. Retrieved 2009-09-23.
Otras lecturas
- Alexander, JE (1977). "Allergic reactions to mask skirts, regulator mouthpieces, and snorkel mouthpieces". South Pacific Underwater Medicine Society Journal. 7 (2). ISSN 0813-1988. OCLC 16986801. Retrieved 2008-07-06.
- Chou, Brian; Legerton, Jerome A; Schwiegerling, Jim (2007). "Improving Underwater Vision: Contact lenses and other options can help patients safely maximize their vision underwater". Contact Lens Spectrum (June). Retrieved 2009-06-27.
- Olsson, DJ; Grant, WD; Glick, JM (2008). "Conjunctivitis outbreak among divers". Undersea and Hyperbaric Medicine. Undersea and Hyperbaric Medical Society. 35 (3): 169–74. PMID 18619112. Retrieved 2009-08-07.
enlaces externos
- Deep Ocean Diving's Ocean Science – Explanation of the physics of underwater vision.