Full face goggles serve as essential protective gear in various environments, from snowy mountains to underwater depths. These goggles provide a comprehensive shield for the eyes and face, enhancing visibility and safety. This article explores the different types of full face goggles and their specific applications.
Full Face Diving Mask
Ski and Snowboard Goggles
Ski and snowboard goggles are designed to protect your eyes from various on-mountain hazards, making your outing a lot more enjoyable. At high altitudes, the air is thinner and filters less ultraviolet (UV) rays. The sun's reflection on snow is brighter and more intense. Wind can make your eyes tear and blur your vision. Ice particles can get into your eyes, as well as twigs and branches when you're dropping through the trees.
Ski goggles and snowboard goggles can help protect your eyes from these on-mountain hazards, making your outing a lot more enjoyable.
Lens Shapes
Lenses are usually either flat or spherical. Cylindrical-lensed goggles are priced lower and work fine, but the flatness can cause more glare and slightly reduces peripheral vision. Curved spherical lenses give better peripheral vision, less distortion and less glare, but the cost is higher. The larger the lens, the better your peripheral vision becomes. Newer to the market are toric lenses, which curve both horizontally and vertically like spherical lenses. The vertical curvature, however, is more subtle than the horizontal one.
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Как выбрать горнолыжную маску? Обзор очков для сноуборда и лыж разных ценовых сегментов.
Ventilation
When warm air from your body heat meets cold air from the outside temperature, condensation can form and your vision is compromised. Goggles use a variety of approaches to avoid fogging. Double-layered lenses are found on virtually all goggles since they do not fog as fast as single-layered lenses. Sealed properly, they create a thermal barrier (like storm windows) that is more resistant to fogging. Anti-fog coatings are integrated into virtually all mid-level to high-end goggle lenses to help deter fogging. Anti-fog products can be used on lower-end goggles without a coating or on old goggles that are starting to fog.
The top, sides and bottom of goggles are the keys to help control fogging. Wider vents generally create better ventilating airflow than smaller venting holes. The trade-off? Your face may get cold, particularly in extreme climates. A few high-end goggles include small, battery-operated fans to help disperse moisture. Fans with different settings can be adjusted for standing in a lift line, riding the gondola or going down the slope.
Visible Light Transmission (VLT) and Lens Color
Your lens color serves to filter and emphasize the colors in your vision. The amount of light that reaches your eyes through the lenses is called the visible light transmission (VLT). Visible light transmission - measured as a percentage - is affected by factors such as the color, thickness, coatings and material of the lenses. Lighter lens tints have a higher VLT because more light passes through the lens. Yellow, gold, amber or rose-colored lenses all offer increased VLT and make good choices on cloudy, socked-in days. Darker tints have lower VLT because less light passes through the lens. Brown, black, gray and lenses all offer reduced VLT and thus excel on bluebird days. Clear lenses are appropriate for night skiing.
VLT Chart
Additional Lens Features
Virtually all goggles sold today offer 100% UV protection from all three types of ultraviolet rays-UVA, UVB and UVC. Remember, even when it's cloudy, UV rays are bouncing off of the snow. These let you easily swap out different colored lenses to suit changing light conditions. Many goggles with interchangeable lenses include two lenses for bright-light and low-light conditions. A polarizing filter's primary function is to reduce glare from sunlight on snow or water. Snow goggles with these lenses automatically change tint level according to conditions and UV intensity. The more sun and UV rays, the darker the lenses become. If it's snowing or overcast the lens stays lighter. Indoors, they always stay light no matter the light intensity. Mirrored lenses have a partial or full lens coating on the outside of the outer lens. This reflects more light and thus allows in less light (by between 10% and 50%) than non-mirrored lenses. Some styles offer advanced technology that may pair with GPS and Bluetooth to display navigation, performance and smartphone information within the goggles in real time.
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Frames and Fit
Make sure to get goggles that fit your face. The fit should be snug (not tight) and comfortable. Some models are best suited for smaller or larger faces; you can often find frames in small, medium, large or XL sizes. Women's and kids' sizes may be available, too. Skiers and snowboarders with higher cheekbones or lower nose bridges might consider goggles in a low bridge fit, which are designed to create a more customized fit. Brands like Smith add extra foam padding and adjust a goggle's frame shape to create a better seal and prevent gaps where wind or snow can get inside. Most snow goggles are designed to work with ski or snowboard helmets, but it's still important to try goggles together with your helmet to ensure a comfortable and flush fit. There should be no space between the top of your goggles and the helmet. Make sure the helmet fits snugly against the goggles-without hindering your vision or pushing down on the goggles. Most goggles have a single, sliding clip to make adjustments. Others may have an open/close buckle with sliding clips on each side for adjustments. This keeps the goggle from pinching your face. Foam should be thick enough to cushion your face but not be so thick that it promotes fogging. High-end goggles may use two or three layers of thin padding to enhance venting. If you wear prescription glasses, look for goggles designed to fit over your glasses, also referred to as OTG (over the glasses) styles. These googles have space to accommodate glasses while avoiding pressure on your face from the temples and nosepiece.
Full-Face Diving Masks
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, demand valve or constant flow gas supply that provides the diver with breathing gas. The full face mask has several functions: it lets the diver see clearly underwater, it provides the diver's face with some protection from cold and polluted water and from stings, such as from jellyfish or coral. Full-face diving masks are often used in professional diving.
The full-face mask provides breathing gas to the diver, and an air space to facilitate underwater vision. There is usually one air space for both breathing and vision, and this is automatically equalised by the breathing gas during descent.
Positive Pressure
For some applications it is desirable for the gas inside the mask or helmet to remain at a pressure slightly above ambient at all times while in the water, as this will prevent any contamination from leaking into the gas space during inhalation if the face or neck seal, or the exhaust valve system, does not seal perfectly. In clean water such a leak is a minor problem, but leaks of contaminated water can be a hazard to health, and even life-threatening. A positive pressure inside a free-flow helmet is easily achieved by slightly increasing the opening pressure of the exhaust valve, provided it is adjustable, but for a demand system the cracking pressure of the demand valve must also be adjusted, so that it delivers gas before the internal pressure drops below external ambient pressure. This is not difficult, as a slight adjustment to second stage valve spring pressure is all that is required.
The problem is that when the mask or helmet is off the diver, and the gas supply is pressurised, the demand valve will leak continuously, and a large amount of gas can be lost.
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Components and Structure
A full-face mask consists of a transparent faceplate (lenses, or window) through which the diver can see, a connection to a source of breathing gas, a means of removing any water which may get inside, some facility for the diver to block the nose to equalise the ears, a means of sealing these components to the diver's face and preventing ingress of water and a means of securing the assembly to the diver's head. The faceplate, viewport, or lens is a transparent window, usually flat, which encloses an air space in front of the diver's eyes and allows the eyes to focus correctly underwater.
The shape and maximum size of mask and helmet viewports changed with availability of tougher and easily moulded transparent synthetic materials: Clear acrylic (perspex) became available in 1933 and polycarbonate in 1958.
A structural component is needed to connect all the working parts together and hold the mask in shape. Most full-face masks use a rigid frame for this purpose, which directly or indirectly connects the components together and holds the assembly in shape.
Face Seal Methods
The frame supporting the functional components must be sealed around the face to maintain a leak free internal air space over the eyes, nose, and mouth. Two methods are used. The soft skirted full-face mask is the more common arrangement, and is generally considerably lighter and more compact than the more sturdy and rigid band masks. A band-mask is a type of full-face diving mask with a rigid and relatively heavy frame, to which a face seal is clamped by a metal band.
Band-masks generally have a single faceplate, which may be relatively large, firmly mounted to a rigid frame which also holds the demand valve or other gas supply components. The frame may be of metal (often brass), a strong engineering plastic, or a fibre reinforced resin composite. A face seal, and in some cases a neoprene hood, is clamped onto the edge of the frame by the metal band which gives the mask configuration its name. Where a hood is included, it may have a zipper up the back for ease of fitting, and the spider is secured over the hood. A band mask is generally heavier and more cumbersome to fit than a soft skirted full-face mask, but it provides greater security and protection to the diver, and is lighter and quicker to fit than a helmet, though less secure.
Mask Securing System
A system of three to five straps is used to secure the mask to the diver's head. This component is often referred to as the spider. It is usually a rubber component comprising a group of straps radiating from a central patch or ring, which rests against the back of the diver's head, low enough to resist slipping off over the top. The straps may pass through quick-adjust buckles attached to the mask skirt, or may have holes to hook onto the buttons of a band mask.
Internal Layout
Four types of internal layout can be distinguished. The simplest arrangement is a single interior space, with no subdivisions, and no mouthpiece. This is most appropriate to free flow systems. In this arrangement the diver can talk clearly, including talking with other divers underwater. There also is the problem of "dead space" inside some masks causing risk of carbon dioxide retention. Free flow air supply overcomes these problems by providing so much air that the mask is constantly flushed. A mouthpiece with bite-grip connects the gas supply directly to the diver's mouth inside the mask. If the mask floods, the diver can continue to breathe while clearing the mask, and it minimises dead space. Many Royal Navy and frogman's rebreathers have this mask arrangement. It makes clear talking difficult, but not impossible.
Unique Configurations
Kirby-Morgan makes a unique configuration of full-face mask, the KM-48 Supermask, which has some characteristics of a half mask, while retaining many of the advantages of the full face mask: The rigid plastic main frame of the mask has a rubber skirt which seals around the eyes and nose like a standard half-mask, the nose may be pinched through the rubber nose pocket to equalise in the same way as with a half mask, and there is an extension to the skirt which seals around the lower part of the face and encloses the mouth. This mask has a clip-on pod section which carries the demand valve, and this part seals against the lower part of the frame, allowing the diver to remove the regulator pod when on the surface, or to use an alternative gas supply, which can either be mounted on another pod, or be an ordinary Scuba regulator second stage with a standard mouthpiece. This feature makes it possible to use bailout gas supplied by a dive buddy with a standard regulator while wearing a Supermask.
Kirby Morgan KM-48 Supermask full face diving mask
Fitting and Adjustments
The full-face mask is generally the last piece of equipment fitted before the dive, as it is cumbersome and makes fitting other equipment more difficult by restricting the diver's field of vision, and the mobility of the head. The fitting may require the help of an attendant, particularly for the heavier band masks. The straps must be tensioned sufficiently to ensure a good seal, and to hold the mask securely to the diver's head, but not so tight as to cause discomfort during the dive.
Equalizing and Defogging
The full-face mask must provide a means for the diver to block the nostrils for equalizing the middle ears. This may be provided in several ways. Some masks have a soft rubber nose pocket which allows the diver to pinch the nose directly, some have a soft cushion which can be pressed against the lower part of the nose to occlude the nostrils, and others have a mechanism which applies soft levers to the sides of the nose to pinch it in the same way that it would be done with fingers. Most full-face masks do not have fresh airflow directly over the interior of the faceplate, and are to some extent susceptible to fogging by condensation during a dive. This may be minimized by application of a demister surfactant before the dive, by rinsing during the dive, or in those cases where the system allows, by purging the mask through a free-flow/defog valve, which directs a flow of dry air over the inner surface of the faceplate.
Emergency Breathing Gas and Bailout Valves
Emergency provision of an alternative breathing gas source is required in case of a failure of the primary gas supply. The most prevalent method for masks intended for surface supply applications is known as a bailout valve. The surface supplied diver generally carries a bailout gas supply sufficient to reach a place of safety based on the planned dive profile. This gas supply is regulated by a scuba first stage regulator, and plumbed into the primary air supply circuit via a bailout valve before it reaches the demand valve. The full face masks designed for surface supply work usually mount this valve on the side of the mask frame, in the bailout block, where it is convenient and easily reached by the diver.
Mask Faceplate and Potential Issues
The mask faceplate is generally a high impact strength polymer which is securely attached to the skirt or frame. A failure of the faceplate can be a life-threatening incident with some full face masks, as the water will flood into the oro-nasal inner mask and compromise the air supply. Not all divers will get a satisfactory seal from the skirt of any given full-face mask, as face shapes and sizes differ, but most divers will be able to find a mask that works for them. A major flood caused by a temporarily dislodged mask is easily drained by purging after replacing it in the correct position, and adjusting the straps if necessary. Lesser leaks will usually drain automatically from the mask through the exhaust valve of the demand valve or a purge valve fitted for that purpose as long as the mask is orientated with the valve at the low point.