Welder World Blog

Posts Tagged ‘gas’

Mild steel welds can be quite difficult to get right if you are not used to this kind of work. It can be one of the most difficult jobs to do when working with mild steel tubes. Hats off, if you can do it well, but it takes a real man to be able to do this job. You will need to wait for the mild steel tube to cool after interval passes, while making sure that you keep the tip extremely hot and shielded with argon. You also have to make sure that you snip the tip of the welding rod if it ever gets crapped up so as to keep your tungsten sharp as it should be.

Purging steel is a very tough thing to do. Mild steel tubes and all the other types of stainless steel products need to be purged with argon gas to prevent them from sugaring or granulation, which is the effect of severe oxidation.

Mild steel welds cannot be complete without an argon purge on the inside surface of common mild steel tube. And this process is done by wrapping aluminum duct tape around the ends of the mild steel tubes while argon gas is left to be trapped inside it.

To be able to determine whether the tube has been purged enough, you need to use an oxygen analyzer; and to make sure that you do a good purge, here are some tips that you can follow:

1. Check that there is no water left inside in mild steel tube. Even a single drop of water will cause damage on the purging process. This is due to the components of water which are hydrogen and oxygen. Wait until all the water will evaporate.

2. You can poke a small hole at the topmost part of the tube to allow the argon gas to flow continuously inside it. Argon should freely flow inside the tube to let all the air out of the tube, as argon is denser than air. Argon will also remove air out of the tube because it has the ability to displace it.

3. Use a diffuser and place it at both ends of your argon hose to ensure a higher flow rate of the gas. A homemade diffuser can be easily fabricated with using stainless steel wool, perforated stainless steel sheet and small piece of sheet metal.

If you are sure that a good purge was done, you can proceed with tacking. You can do this by getting the tape off to let the tack cool down, after which you should re tape it. The tacking should be done 180 degrees apart.

There are more tips that you can follow when welding stainless steel pipe.

1. Instead of using a 3/32 inch rod, you should use a 1/8 inch wire to do better welding.

2. Re-welding can be done on impenetrable areas.

3. Prefer to use stainless steel wire brushes and files which are for stainless steel alone.

4. To avoid overheating, use enough amperage.

Tig welding an end cap on a post 1.5mm-3mm x 80mm box section.
Video Rating: 5 / 5

Find More Welding Mild Steel Articles

Air compressors are useful mechanical devices that are used for the purpose of transforming power such as gas or electricity into another form of energy referred to as kinetic through a process called compression. Compression results from either filling and releasing air or accelerating and decelerating air. When air is compressed through either of these ways, it is has many uses. Air compressors are commonly used in a number of home improvement tools such as staplers and spray guns. They are also commonly used in the removal of rubbish and they can be bought through a number of online resources.

Heavy duty air compressors are designed for industrial processes and offer more value for money because the air storage is long lasting and uses less energy for optimal functions. A quality air compressor should constitute essential safety features such as valves that allow the release of air in instances when the pressure in the tank is too much. Belt guards are other features that enhance the safety of the device.

Air tools require gas as a source of energy to perform their functions. This gas is typically derived from gas compressors that contain compressed air. Portable cylinders contain carbon dioxide that makes the device lighter and easier to move around with. A key advantage of air tools is that they are affordable in comparison to electric tools and they are easier to maintain. Air tools are also considerably much safer to use than those that are powered by electricity. Te portability and compact size do not comprise the ability of the tool to carry out essential tasks effectively. Many people use air tools around their homes and they can also be found in fully fledged industries. A light and portable air tool can effortlessly enable the user to perform tough jobs while providing impressive speed as well as heightened performance. Examples of air tools are drills, polishers and hammers.

MIG welders can be used for both domestic and commercial purposes. Air tools are especially useful when access to other forms of power is limited. It is important to choose the correct MIG welder based on what it is required. Welders are used for functions such as fabrication, repair and manufacturing.  For MIG welding to be achieved, a wire feed is required. This wire is passed through a tip that is heated and the action of pulling the trigger causes the wire to melt thereby forming what is referred to as weld puddles. It is easy to learn how to go through the MIG welding process MIG welders are high in productivity and are not messy to use. They are also able to cater for various positions and metals like steel.

Sealey tools consist of quality products such as drill press vices, wrenches, saws, ventilators and screwdrivers. These tools are essential for any workshop or industry tasks. Pressure washers function by using a high amount of pressure that releases water for extensive cleaning purposes that involve cars, buildings and roads. Tool boxes help to ensure that everything is kept in order and that all the tools that one needs can be easily located. Good tool boxes should be portable with adequate compartments for storage.

A comparison between Eastwood’s MIG 135 Welder and the leading competitor’s welder. Check out our entire welding line here: www.eastwood.com

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The popular jewelry manufacturing procedure was already recognized for the use of gas welding in mid nineteenth century also, but only a blend of hydrogen and oxygen was used in the process as, together, they formed a very intense and hot blaze. It was the invention of acetylene at the end of the same century that shaped gas welding what it is today. Acetylene is a gas that is formed by the chemical grouping of water and calcium carbide; in gas welding, this amalgam may provide flames up to 4000 degrees Fahrenheit. Currently, it is pretty common to use a combination of acetylene and oxygen in gas welding to acquire a higher temperature of 6000 deg. F.

The advantages of gas welding include lower costs, mobility of LPG equipment transport and flexibility, compared to the use of electric set ups. Moreover, there is no difference in terms of performance since any metal can be welded, cut or heated using a gas welding tool on oxygen and acetylene. If you choose gas welding, ensure that cylinders need to be kept in a vertical order, and that the caps of valve should be in right place when the cylinders are not in use.

The cylinders are associated between them and the torch with all sorts of hoses, available in various sizes; one prominent mention here is that all hoses used in gas welding need to be marked with the kind of repair level they are meant for: light, normal, or heavy. When purchasing the LPG equipment, make sure that you know all the details for the rubber welding hoses. The user of Gas welding is exposed to the danger of combustion in the hoses and regulators; hence, daily valve tests are required in order to ward off flashbacks.

Some of the gas welding tools are specifically designed to curb flashbacks; which is acquired with the help of a flashback arrestor. This device is identical to a check valve, but it also includes a trap that cuts of the gas flow when flashback occurs; hence, arrestors are a must-have type of LPG equipment that is important for those who use gas welding equipments.

Gas Welding Safety Tips

To lift up gas cylinders, use the LPG equipments that are designed to perform that task.

Check torches and clean only using suitable tools.

While welding use blowback guard torches.

Always keep a watch on the LPG equipment and fix any leakages at all connections.

Check hoses for worn and leaks spots.

Keep fire extinguishers at handy places, at the welding site.

Keep cylinders and hoses away from flames, sparks, to avoid any holes on it.

Use a flint lighter to fire the flame in welder.

Use two-stage regulators whenever required.

Open cylinder valves very slowly when using a single-stage regulator.

During using a single-stage regulator, open only the acetylene cylinder valve 1/4 to 3/4 turn.

Keep the wrench in place. In this way you can close the cylinder easily and quickly in case of any emergency.

Established in 1993, Riland Industry Co., Ltd. is the first manufacturer of inverter welding machines in China. With 16 years of R&D effort, today Riland has become the leader in manufacturing inverter welding/cutting power source and integrated automatic welding equipment sets. For details, please contact benjamin@riland.com.cn

Find More Gas Welding Sets Articles

In the expansion of the aluminum industry, aluminum castings have played a vital role. Anyone who is into the business of metal castings must be willing to learn some tips of welding aluminum castings with less amperage. There are few Tig welding inverters that can help you to meet your objective of power saving why you try to weld your castings in aluminum. These inverters use power as low as 115v only. These machines are first-class power sources but their output is limited to 200 amps only. At 200 amps, it’s not hot enough enabling you to weld with more comfort.

Another proven method to reduce amperage during welding is the preheating of the aluminum parts at a temperature of 200 degree. For preheating aluminum castings, you may use either a furnace or an oxy-fuel torch. But if you won’t have these two tools in place, still you have options to lower your amperage. Now in such a case, you need a gas grill. You may spare a gas grill just for preheating of aluminum parts but not for cooking anything on it. When you are ready with your gas grill, use aluminum foil to wrap the part to be preheated. Then put it on the oven. Keep the flame at medium and allow the heat to conduct through the part. Using a small propane torch won’t be a bad idea to make the part hot enough by moving the torch over it.

If you didn’t like the idea of using gas grill, here is another tip for you to reduce the amperage. When you try to Tig welding aluminum castings with less amperage, prefer using a 50-50 helium/argon mix as a substitute of straight argon. This mix does the magic, as helium provides more energy. Especially, for thick aluminum, use of helium is generally recommended. Helium adds more voltage to aluminum arc and supply of extra current is not needed. For aluminum with a thickness less than ? inch, use of straight argon can be a sensible choice.

Still, there is one great tip for Tig welding aluminum castings with low amperage. Now, you can think using a small Tig cup. Sometimes it is also called as Tig welding nozzle. This is actually a ceramic tip that is fixed at the end of the Tig torch. This Tig cup allows release of less shielding gas and prevents the oxidation of the tungsten electrode. The idea is not to use too much torch gas. The less amount of gas projected on the aluminum parts demands for less mount of amperage. Moreover, the degenerated arc energy adds to the gas shielding. Thus, welding parts get an extra amount of energy. In fact, allowing too much gas to flow will make it difficult to work with it.

Today, aluminum industry is a well-developed industry and hundreds of compositions of aluminum alloy castings are available keeping in mind their commercial usage. In most types of commercial casting processes, these tips for Tig welding aluminum castings will be greatly beneficial to reduce amperage.

More Propane Torch Welding Articles

For many industrial applications, welding can expedite the process, ensure consistent quality, and reduce costs. In addition, welding equipments in Australia is generally a safer machine tool means workplace safety increases as well. Welding is becoming more commonplace in industrial settings, and researchers continue to develop new welding methods and gain greater understanding of weld quality and properties.

When all industrial projects struggle for the same available by lot of wealth, have you ever think about, how can welding engineers, welding production supervisors or operations managers make their demand for new welding equipments stand out from challenging assignments?

Profitable Welding Equipments First-Rated Effectiveness On Investment The Clear Choice

Up to date industrialized and high volume production operations must be a focal point on continuous improvement to remain lucrative and aggressive. Constant improvement in mechanized companies can take many forms. Digital organize equipment can also subordinate costs connected with examination, weld testing, engineering evaluation, disposition and subsequent rephrase. These are the key aspects of technologies can even assist defeat the shortage of skilled welding workforce.

Productively attain new welding equipments, people such as welding engineers and maintenance superintendents also understand the time value of for the investments done by their industrial clients. Manual labor may report for an important segment of your total developed costs, but it is uniformly imperative to comprehend material costs, deployment costs and cost prevention prospects, particularly if manufacturing rates are greater than ever.  Each situation will differ. To help you understand you’re welding work costs and to achieve a precious external perception — work with welding equipment suppliers and dealers who take an advice-giving come up to.

Welding Equipments Authentic For Manufacturing Unit, Just The Best

One of the oldest forms of welding, gas welding is still extensively used nowadays for numerous applications. Using an open flame and combining oxygen and acetylene, this is a flexible and relatively forgiving welding process. While still used by many for welding, this expertise is used more and more for either cutting or brazing operations. Because of its manageability and flexibility via controlling or adjusting gas mixtures, the welder can execute many different operations with this type of welding equipment.

MIG welders, or Metal Inert Gas welders, get their name from the development of commencing gas around the welding curve. This gas, frequently carbon dioxide or argon or a combination of both, make sure a spotless background for the curve with fewer possibility of oxidation.

When considering purchasing a MIG welder, it is significant to make your mind up for what kinds of substances and what amount you plan to use the welder. One decision you need to think about in the beginning is where you will use the machine and what your options for electricity supply are.

Mainly auto shops have 220-volt current obtainable, while it is less accessible in suburban garages. There are some good 110V MIG welders available from Australia, but you will definitely be limited to the types of substances that you will be able to work with. One benefit of these minor machines is manageability. Not only are these machines lighter and less important, they also can utilize smaller gas tanks, which is good for storage space and progress.

Learn setting up the welding machine from an expert in arc, tig and mig welding in this free DIY video. Expert: Malcolm MacDonald Bio: Malcolm MacDonald graduated from Connestoga College in 1968 taking the Fitter Welding Program. Filmmaker: Melissa Schenk
Video Rating: 4 / 5

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The interest for cooking has been increasing exponentially in modern times. But as time goes by, the techniques to put up the greatest and best tasting meals are gradually shifting from manual operations to gadget-geared ones. Molecular gastronomy is definitely making history in kitchens! If you want to get a taste of such professional sounding cookery technique, you better get the right gas cylinders for food preparation.

These vessels contain gases at their liquefied states. Since the gases stored in them are at higher pressurized levels, these containers are made from durable metal material such as steel or aluminum alloy.

In the older times, they were merely used for industrial purposes such as welding or other mechanical procedures. But through time with the rise of discovering innovative cooking techniques that involve high regard to the molecular composition of food, these gas cylinders have transformed into being useful cooking equipment.

One of the most popular types of such vessels used for cooking or food preparation is the nitrous oxide cartridges. This kind is under the Case II classification of such gas containers. This category means that the substance, as in the nitrous oxide gas, only reaches its liquefied state when standard temperature with increased pressure is applied on it.

These metal containers are also known by a lot of names – whipped cream chargers, whippets or whippers. The smallest kind contains 8 grams of pure nitrous oxide while the bigger types come in 16 gram cylinders. They typically come in thumb size tubes measuring about 2.5 inches long and .7 inches wide. At first sight, they look like gun bullets due their structure – a narrow tip with a rounded end.

But for the cylinders used for industrial or commercial kitchen purposes, nitrous oxide tanks are larger both in height, weight and structure. These often involve a gas tank system that permits about ten liters of whipped cream will be produced per hour. This kind of vessels is usually used in coffee shops or patisseries.

For froths, foams or whipped cream to be produced, the vessel has to be attached to a dispenser. Upon doing so, the gas will be released into the other container, which should firstly contained prepared cream (preferably with at least 28% fat content).

Afterwards, the nitrous oxide cartridges will do the work. It will aid the process of producing bubbles in large amounts, which in the end would produce cream with the all new fluffy texture. The mentioned fat content in the cream to be put inside the canister is crucial. The rule of thumb is that the higher the fat content, the more fat molecules could be worked up and turned into a puffed coating of the cream. The lesser content might mean the whipped cream could instantly become watery.

The best thing about the gas cylinders such as the nitrous oxide cartridges is that they empower even the simplest people. You for one now have the power and capability to put up a great dish that might even deserve to rival those meals in restaurants!

Welding is mostly used for the combination processes i.e. arc, resistance, laser, electron beam, stud and orbital welding.

Weld controllers are required to help the processes used by these tools. Welding machines also work as aid to welding power source. There are also wide-ranging system to cutting machine, torch, feeders, cables, robots and feeders. This article describes the purpose of arc welding in detail.

Arc welding methods and welding machines

For melting the metals at welding point, Arc welding is utilizing welding power supply to produce an electric arc between the base material and an electrode. Arc welding equipments can use either direct current or alternating current, and consumable or non-consumable electrodes. Shielding gas protects welding region using some inert or semi-inert gas and evaporate wadding material. The method of arc welding is broadly recognized for low capital and running costs.

MIG (Metal Inert Gas) welding and TIG welding are the two general specifications of Arc Welding. MIG is also acronym as MAG (metal active gas welding) and regarded as one of the mostly popular arc welding methods. MIG welding equipments uses various kinds of gas like pure carbon dioxide, argon gas and some time blend of both to complete the process.

TIG (Tungsten Inert Gas) Welding is another latest welding process.  This term stands for its utilization when shaping an arc in between the electrode and the item. Argon is use to inert gas portion in welding. TIG welding is slower compare to MIG and at the same time more expensive.

Arc welding has other methods like flux cored arc welding, gas metal arc welding, resistance seam welding, spot and shielded metal arc welding.

More welding measures serve by arc welding machines

Frictional welding is also a type of welding equipments. Examples of friction welding machines are hot plate welding, plastic welding, electron beam welding and Oxyfuel welding.

Despite the diversities in arc welding procedures, the purposes that are common is it all stops rust, serve varying actions and render water cooling uses. Of course heavy-duty equipment with engine driven generators is the best to fulfill these methods.

Gas Welding is alive and well!
* If you want to create artistic projects, many people will choose gas welding exclusively.
* At some point, most arc welders will want to, or NEED to use gas welding. I’ll help you get started. Then YOU need lots of practice!

Seriously, practice is CRITICAL for running great beads.
* If you’re doing artistic stuff, you’ll want it to LOOK great.
* Eye-hand coordination gets tougher because you’re doing more multi-tasking then arc welding.
Being able to DIRECTLY be shown details about how to do special jobs like gas welding is the BEST way to get started. (By WATCHING some else gas weld).

Here’s the “scoop” for this article:
1) I’ll give you a brief introduction to the gas welding world…
2) Then I’ll hit on some safety tips…
3) Next the equipment itself…
4) Getting started:
* The flame.
* Adjustments.
* Angles.
5) Filler rod, tacking, the puddle, problem solving.
6) Brazing Tips.

INTRO:
* Gas welding in this page refers to oxygen-acetylene welding of metals.
* Your are actually WELDING two pieces of metal together, wheras brazing doesn’t melt the parent material, just the material used to join the pieces.
* The torch itself needs to be able to melt the metals being used: filler rod, & “parent metals”.
* Having an oxygen-acetylene torch around enables you to not only WELD, but also to cut the materials, heat & bend materials, & loosen tight-fitting materials via heating.
* Safety is paramount! You are working with extremely hot & potentially explosive materials!

SAFETY STUFF:
SERIOUSLY gas welding can really be fun, interesting, & profitable!
BUT:
* The tuned gas flame can exceed 6,000 F.
* Un-protected eyes can be fatigued & permanently harmed in a short time.
* The acetylene tank could explode under certain conditions: dropping, in a fire, from an arc or torch flame penetrating the casing, etc.
* The oxygen tank starts with 2000 PSI & can literally go like a rocket if the top valve assembly breaks off.
* Hitting something already burning with the high pressure torch valve can really accelerate the fire.

So, be careful!

GETTING STARTED:

The Flame:
* Set the gas and oxygen pressures MUCH lower than for cutting.
* Some gas setting charts call for the 02 & gas pressures to be the same as the tip size being used: tip size 1 = 1 PSI for gas & O2.
* Tip size 5 = 5 PSI for gas & O2, etc.
* I simplify things even farther! I just set both pressures at 10 PSI then crack the valves open at the torch handle to where I need them to be. Just start EASY & work them up to the capabilities of the tip. (or just do it as above).
* Also, tip sizes vary for the size metal being welded: Tip size 1 = 1/16″ metal and tip size 5 = 1/4″ as examples.
* It really isn’t hard to figure out if the tip your using is too small or too big for the job. (Too small won’t get everything hot enough, & too large will tend to blow everything away).
* Crack open the gas & light it right away.
* Crank up the gas till it separates from the tip then back it off.
* Hit the O2 until the blue flame first gets short & bright. This is a “neutral flame”, used for most jobs.

Note that the torch tip & the filler rod should be about at a 45 degree angle.
*Too steep can make the penetration too deep & not pre-heat / too shallow can cause too little penetration.

Let’s do it:
* Starting out, it can give you good practice to just put the flame on metal without a filler rod. This helps you get used to the process without worrying about the filler rod too.
* Heat the metal till there’s a puddle, then begin moving the flame to create a bead.
* Get the blue part of the flame nearly touching the metal.
* Move in a circular or semi-circular fashion to make it into a bead.
* Aim the flame in the direction you’re trying to make the bead. (forehand welding).
* Don’t get ahead of the bead or it can make it not hot enough at the puddle.
* Do this for a few times before using a filler rod.

Introduce a filler rod: (usually the same diameter as the pieces that are being welded).
* start the same way as above and keep the rod at a 45 degree angle also.
* Dip the rod in the puddle frequently, but try not to heat the rod with the flame. (heat the puddle, not the rod).
* Practice running straight beads then work up to following curved paths. (some schools have you write your name with a gas welding bead).

THEN PRACTICE till you can run decent looking beads.

Note that you should be tacking pieces together at least at both ends of where you’re welding, to prevent moving of the gap.

Problem solving:
* Your flame is fluctuating: gas pressure or supply may be low.
* Popping sound: Hot tip, plugged tip, pressure too high.
* Flame stops: 02 pressure high.
* Whistling noise & the flame backs up into the torch: (backfire), 02 or gas too low, the tip is clogged or dirty, or the tip touched the puddle.

BRAZING:
* Many things are similar about gas welding and brazing: but remember that with brazing you aren’t melting the parent metal, just the brazing material (such as brass).
* The brass and the parent metal MUST be clean and hot enough for there to be a good joint. (Use flux! In a can, or coated rods).
* Think of soldering, if you don’t get everything hot enough, it might come apart (or not be a good electrical connection).

Now GET BUSY PRACTICING!

This was a just a BRIEF description of the gas welding process.

Good luck to all you ladies & gents!

SVI Gas Saver Applications

LPG / Natural Gas / CNG  are a vital component of the world’s supply of energy. It is one of the cleanest, safest, and most useful of all energy sources. SVI Gas Savers are effective with all these energy sources. 

Commercial establishments such as Hotels, Restaurants, Caterers, Resorts, Clubs, Cafes, Sweet Shops, Canteens, etc and other institutions such as Hospitals and Hostels choose SVI Gas Saver because of its cost effective results. 

We make businesses more cost-effective, clean and keep customers smiling. 

Cooking ifferent types of cooking are efficiently performed using SVI Gas Saver: Boiling, Stewing, Frying, Grilling, Toasting, Broiling, Roasting, Baking, etc. 

Water Heating: Hotels and Inns need to provide hot water for bathrooms, spas and swimming pools for comfort of their guests.

SVI Gas Saver has been proven to be a cost effective and reduces pollution. 

Laundry: Hotels, Hospitals and other such establishments require steam and hot-water for laundry.

SVI Gas Saver has been proven to be a cost effective and reduces pollution. 

Air Conditioning: SVI Gas Saver can be used in Vapour absorption chillers (used for air-conditioning) to save on huge gas costs required for running traditional air conditioners. 

Incineration: Hospitals and Laboratories generate hazardous bio-medical waste which needs to be incinerated for safe disposal.

SVI Gas Saver is used in heavy incinerators applications for complete burning of the bio-medical waste with reduced harmful emissions and cost. 

Industries require cost-effective and efficient energy solutions for their various processes. In most applications, SVI Gas Saver can be used as a clean and cost-effective solution in furnaces, kilns, ovens, dryers, boilers, hot air generators, etc. Some of which are described below.

Agriculture : SVI GAS SAVER  finds application for drying of various agricultural crops like drying of seeds and pulses, roasting of peanuts, curing of tobacco, etc.

Drying with SVI GAS SAVER  is economical. 

Automobile and Auto Ancillary :SVI GAS SAVER is used for production of automobile components like engine blocks, gears & transmission parts, springs, alloy wheels etc.

SVI GAS SAVER is also used in paint-shop and powder coating units in these industries. 

Ceramics: SVI GAS SAVER is used in kilns and furnaces in the ceramic industry for manufacturing tableware, decorative earthenware, sanitary ware, electrical insulators, etc. 

Chemicals, Paints & Dyes, Soaps & Detergents: SVI GAS SAVER is used in chemical industries for process heating (through steam), roasting and drying of chemicals. 

Dairy: SVI GAS SAVER is used in Dairy industries for process heating, cleaning and drying applications.

The energy source is usually steam or hot water generated through boilers / thermic fluid heaters which uses SVI Gas Savers. 

Ferrous & Non-Ferrous Metals: Typical applications like melting, pre-heating of ingots/bars, various forms of heat treatment, protective surface coatings, etc. uses gas which can be reduced by using SVI Gas Savers. 

Engineering & Fabrication : SVI GAS SAVER  is used in engineering and metal fabrication processes for cutting & joining metals – both ferrous and non-ferrous.

Natural Gas / LPG is a cost-effective option for oxy-gas cutting compared to acetylene, and in brazing furnaces compared to diesel. When there is Natural Gas / LPG there is SVI Gas Savers. 

Food & Beverages : SVI GAS SAVER is used in bakeries for baking of breads, cakes & biscuits, in biscuit units for baking of wafers & cream biscuits. 

Glass : SVI GAS SAVER  is used in glass industries for various processes like glass feeders, annealing lehrs, glass cutting and fire polishing, melting, etc. 

Surface Coatings: The applications include curing of paint after spray painting, baking of powder coated articles, galvanizing and other protective metal coatings uses SVI Gas Savers. 

Paper & Packaging: SVI GAS SAVER is used paper industries for drying to produce high quality paper sheets, and also in the manufacture of packaging materials like corrugated sheets, rolls and boxes. 

Pharmaceutical: SVI GAS SAVER is perfectly suited for Pharmaceutical industries which need steam in a variety of processes, without compromising on clean ambience and high environmental standards. 

Plastics: SVI GAS SAVER is used in plastic industries for heating in injection moulding process and rotomoulding process to produce wide variety of plastic articles such as bottles, storage tanks, containers, etc. 

Printing: SVI GAS SAVER is used in the print industry for drying of ink to produce high quality glossy prints for magazines, etc. 

Textile: SVI GAS SAVER is used in textile & garments industry for numerous applications – Singeing (burning off loose yarn for better fabric finish), Calendaring (another finishing process), Drying after printing on fabrics and Steam generation. 

Others: SVI GAS SAVER powering applications in other industries such as Batteries, Blades, Woven & non-woven sacs, Electrical & Electronics, Consumer Goods, etc And we are finding more and more.

History

Main article: timeline of underwater technology

Original Aqualung SCUBA set

The first commercially successful scuba sets were the Aqualung open-circuit units developed by Emile Gagnan and Jacques-Yves Cousteau, in which compressed gas (usually air) is inhaled from a tank and then exhaled into the water, and the descendants of these systems are still the most popular units today.

The open circuit systems were developed after Cousteau had a number of incidents of oxygen toxicity using a rebreather system, in which exhaled air is reprocessed to remove carbon dioxide. Modern versions of rebreather systems (both semi-closed circuit and closed circuit) are still available today, and form the second main type of scuba unit, most commonly used for technical diving, such as deep diving.

Etymology

The term SCUBA (an acronym for Self-Contained Underwater Breathing Apparatus) arose during World War II, and originally referred to United States combat frogmen’s oxygen rebreathers, developed by Dr. Christian Lambertsen for underwater warfare.

The word SCUBA began as an acronym, but it is now usually thought of as a regular wordcuba. It has become acceptable to refer to “scuba equipment” or “scuba apparatus”xamples of the linguistic RAS syndrome.

Types of diving

Professional diver performing underwater welding

See also: Recreational diving and Professional diving

Scuba diving may be performed for a number of reasons, both personal and professional. Most people begin though recreational diving, which is performed purely for enjoyment and has a number of distinct technical disciplines to increase interest underwater, such as cave diving, wreck diving, ice diving and deep diving.

Divers may be employed professionally to perform tasks underwater. Most of these commercial divers are employed to perform tasks related to the running of a business involving deep water, including civil engineering tasks such as in oil exploration, underwater welding or offshore construction. Commercial divers may also be employed to perform tasks specifically related to marine activities, such as naval diving, including the repair and inspection of boats and ships, salvage of wrecks or underwater fishing, like spear fishing.

Other specialist areas of diving include military diving, with a long history of military frogmen in various roles. They can perform roles including direct combat, infiltration behind enemy lines, placing mines or using a manned torpedo, bomb disposal or engineering operations. In civilian operations, many police forces operate police diving teams to perform search and recovery or search and rescue operations and to assist with the detection of crime which may involve bodies of water. In some cases diver rescue teams may also be part of a fire department or lifeguard unit.

Lastly, there are professional divers involved with the water itself, such as underwater photography or underwater filming divers, who set out to document the underwater world, or scientific diving, including marine biology and underwater archaeology.

Reasons for diving may include:

Type of diving

Classification

aquarium maintenance in large public aquariums

commercial, scientific

boat and ship inspection, cleaning and maintenance

commercial, naval

cave diving

technical, recreational

civil engineering in harbors, water supply, and drainage systems

commercial

crude oil industry and other offshore construction and maintenance

commercial

demolition and salvage of ship wrecks

commercial, naval

diver training for reward

professional

fish farm maintenance

commercial

fishing, e.g. for abalones, crabs, lobsters, pearls, scallops, sea crayfish, sponges

commercial

frogman, manned torpedo

military

harbor clearance and maintenance

commercial, military

media diving: making television programs, etc.

professional

mine clearance and bomb disposal, disposing of unexploded ordnance

military, naval

pleasure, leisure, sport

recreational

underwater photography

professional, recreational

policing: diving to investigate or arrest unauthorized divers

police diving, military, naval

search and recovery diving

commercial

search and rescue diving

police

spear fishing

professional (occasionally), recreational

stealthy infiltration

military

marine biology

scientific, recreational

underwater tourism

recreational

underwater archaeology (shipwrecks; harbors, and buildings)

scientific, recreational

underwater welding

commercial

Breathing underwater

For more information, see Diving regulator.

Scuba diver on reef

Water normally contains dissolved oxygen from which fish and other aquatic animals extract all their required oxygen as the water flows past their gills. Humans lack gills and do not otherwise have the capacity to breathe underwater unaided by external devices. Although the feasibility of filling and artificially ventilating the lungs with a dedicated liquid (Liquid breathing) has been established for some time, the size and complexity of the equipment allows only for medical applications with current technology.

Early diving experimenters quickly discovered it is not enough simply to supply air in order to breathe comfortably underwater. As one descends, in addition to the normal atmospheric pressure, water exerts increasing pressure on the chest and lungspproximately 1 bar or 14.7 psi for every 33 feet or 10 meters of deptho the pressure of the inhaled breath must almost exactly counter the surrounding or ambient pressure to inflate the lungs. It generally becomes difficult to breathe through a tube past three feet under the water.

By always providing the breathing gas at ambient pressure, modern demand valve regulators ensure the diver can inhale and exhale naturally and virtually effortlessly, regardless of depth.

Because the diver’s nose and eyes are covered by a diving mask; the diver cannot breathe in through the nose, except when wearing a full face diving mask. However, inhaling from a regulator’s mouthpiece becomes second nature very quickly.

Open-circuit

The most commonly used scuba set today is the “single-hose” open circuit 2-stage diving regulator, coupled to a single pressurized gas cylinder, with the first stage on the cylinder and the second stage at the mouthpiece. This arrangement differs from Emile Gagnan’s and Jacques Cousteau’s original 1942 “twin-hose” design, known as the Aqua-lung, in which the cylinder’s pressure was reduced to ambient pressure in one or two or three stages which were all on the cylinder. The “single-hose” system has significant advantages over the original system.

In the “single-hose” two-stage design, the first stage regulator reduces the cylinder pressure of about 200 bar (3000 psi) to an intermediate level of about 10 bar (145 psi) The second stage demand valve regulator, connected via a low pressure hose to the first stage, delivers the breathing gas at the correct ambient pressure to the diver’s mouth and lungs. The diver’s exhaled gases are exhausted directly to the environment as waste. The first stage typically has at least one outlet delivering breathing gas at unreduced tank pressure. This is connected to the diver’s pressure gauge or computer, in order to show how much breathing gas remains.

Rebreather

An Inspiration electronic fully closed circuit rebreather

Main article: Rebreathers

Less common are closed and semi-closed rebreathers, which unlike open-circuit sets that vent off all exhaled gases, reprocess each exhaled breath for re-use by removing the carbon dioxide buildup and replacing the oxygen used by the diver.

Rebreathers release few or no gas bubbles into the water, and use much less oxygen per hour because exhaled oxygen is recovered; this has advantages for research, military, photography, and other applications. The first modern rebreather was the MK-19 that was developed at S-Tron by Ralph Osterhout that was the first electronic system.[citation needed] Rebreathers are more complex and more expensive than sport open-circuit scuba, and need special training and maintenance to be safely used.

Because the nitrogen in the system is kept to a minimum, decompressing is much less complicated than traditional open-circuit scuba systems and, as a result, divers can stay down longer. Because rebreathers produce very few bubbles, they do not disturb marine life or make a diver presence known; this is useful for underwater photography, and for covert work.

Gas mixtures

Nitrox cylinder marked up for use

Main article: Breathing gas

For some diving, gas mixtures other than normal atmospheric air (21% oxygen, 78% nitrogen, 1% trace gases) can be used, so long as the diver is properly trained in their use. The most commonly used mixture is Enriched Air Nitrox, which is air with extra oxygen, often with 32% or 36% oxygen, and thus less nitrogen, reducing the likelihood of decompression sickness. The reduced nitrogen may also allow for no or less decompression stop times and a shorter surface interval between dives. A common misconception is that nitrox can reduce narcosis, but research has shown that oxygen is also narcotic.

Several other common gas mixtures are in use, and all need specialized training. The increased oxygen levels in nitrox help fend off decompression sickness; however, below the maximum operating depth of the mixture, the increased partial pressure of oxygen can lead to oxygen toxicity. To displace nitrogen without the increased oxygen concentration, other diluents can be used, often helium, when the resultant mixture is called trimix.

For technical dives, some of the cylinders may contain different gas mixture for each phase of the dive, typically designated as Travel, Bottom, and Decompression. These different gas mixtures may be used to extend bottom time, reduce inert gas narcotic effects, and reduce decompression times.

Hazards and dangers

According to a 1970 North American study, diving was (on a man-hours based criteria) 96 times more dangerous than driving an automobile. According to a 2000 Japanese study, every hour of recreational diving is 36 to 62 times riskier than automobile driving.

Injuries due to changes in air pressure

For a full list, see Diving hazards and precautions.

Divers must avoid injuries caused by changes in air pressure. The weight of the water column above the diver causes an increase in air pressure in any compressible material (wetsuit, lungs, sinus) in proportion to depth, in the same way that atmospheric air causes a pressure of 101.3 kPa (14.7 pounds-force per square inch) at sea level. Pressure injuries are called barotrauma and can be quite painful, in severe cases causing a ruptured eardrum or damage to the sinuses. To avoid them, the diver equalizes the pressure in all air spaces with the surrounding water pressure when changing depth. The middle ear and sinus are equalized using one or more of several techniques, which is referred to as clearing the ears.

The mask is equalized by periodically exhaling through the nose.

If a drysuit is worn, it too must be equalized by inflation and deflation, similar to a buoyancy compensator.

If properly equalized, the sinus passages can stand the increased pressure of the water with no problems. However, congestion due to cold, flu or allergies may impair the ability to equalize the pressure. This may result in permanent damage to the eardrum. Although there are many dangers involved in scuba diving, divers can decrease the dangers through proper training and education. Open-water certification programs highlight diving physiology, safe diving practices, and diving hazards.

Effects of breathing high pressure gas

Decompression sickness

Main article: Decompression sickness

The diver must avoid the formation of gas bubbles in the body, called decompression sickness or ‘the bends’, by releasing the water pressure on the body slowly while ascending and allowing gases trapped in the bloodstream to gradually break solution and leave the body, called “off-gassing.” This is done by making safety stops or decompression stops and ascending slowly using dive computers or decompression tables for guidance. Decompression sickness must be treated promptly, typically in a recompression chamber. Administering enriched-oxygen breathing gas or pure oxygen to a decompression sickness stricken diver on the surface is a good form of first aid for decompression sickness, although fatality or permanent disability may still occur.

Nitrogen narcosis

Main article: Nitrogen narcosis

Nitrogen narcosis or inert gas narcosis is a reversible alteration in consciousness producing a state similar to alcohol intoxication in divers who breathe high pressure gas at depth. The mechanism is similar to that of nitrous oxide, or “laughing gas,” administered as anesthesia. Being “narced” can impair judgment and make diving very dangerous. Narcosis starts to affect some divers at 66 feet (20 meters). At 66 feet (20 m), Narcosis manifests itself as slight giddiness. The effects increase drastically with the increase in depth. Almost all divers are able to notice the effects by 132 feet (40 meters). At these depths divers may feel euphoria, anxiety, loss of coordination and lack of concentration. At extreme depths, hallucinogenic reaction and tunnel vision can occur. Jacques Cousteau famously described it as the “rapture of the deep”. Nitrogen narcosis occurs quickly and the symptoms typically disappear during the ascent, so that divers often fail to realize they were ever affected. It affects individual divers at varying depths and conditions, and can even vary from dive to dive under identical conditions. However, diving with trimix or heliox dramatically reduces the effects of inert gas narcosis.

Oxygen toxicity

Main article: Oxygen toxicity

Oxygen toxicity occurs when oxygen in the body exceeds a safe “partial pressure” (PPO2). In extreme cases it affects the central nervous system and causes a seizure, which can result in the diver spitting out his regulator and drowning. Oxygen toxicity is preventable provided one never exceeds the established maximum depth of a given breathing gas. For deep dives (generally past 180 feet / 55 meters), divers use “hypoxic blends” containing a lower percentage of oxygen than atmospheric air. For more information, see Oxygen toxicity.

Refraction and underwater vision

Main article: Underwater vision

A diver wearing an Ocean Reef full face mask

Water has a higher refractive index than air; it’s similar to that of the cornea of the eye. Light entering the cornea from water is hardly refracted at all, leaving only the eye’s crystalline lens to focus light. This leads to very severe hypermetropia. People with severe myopia, therefore, can see better underwater without a mask than normal-sighted people.

Diving masks and diving helmets and fullface masks solve this problem by creating an air space in front of the diver’s eyes. The refraction error created by the water is mostly corrected as the light travels from water to air through a flat lens, except that objects appear approximately 34% bigger and 25% closer in salt water than they actually are. Therefore total field-of-view is significantly reduced and eye-hand coordination must be adjusted.

(This affects underwater photography: a camera seeing through a flat window in its casing is affected the same as its user’s eye seeing through a flat mask window, and so its user must focus for the apparent distance to target, not for the real distance.)

Divers who need corrective lenses to see clearly outside the water would normally need the same prescription while wearing a mask. Generic and custom corrective lenses are available for some two-window masks. Custom lenses can be bonded onto masks that have a single front window.

A “double-dome mask” has curved windows in an attempt to cure these faults, but this causes a refraction problem of its own.

Commando frogmen concerned about revealing their position when light reflects from the glass surface of their diving masks may instead use special contact lenses to see underwater.

As a diver descends, he must periodically exhale through his nose to equalize the internal pressure of the mask with that of the surrounding water. Swimming goggles are not suitable for diving because they only cover the eyes and thus do not allow for equalization. Failure to equalise the pressure inside the mask may lead to a form of barotrauma known as mask squeeze.

Controlling buoyancy underwater

Diver under the Salt Pier in Bonaire.

To dive safely, divers must control their rate of descent and ascent in the water. Ignoring other forces such as water currents and swimming, the diver’s overall buoyancy determines whether he ascends or descends. Equipment such as the diving weighting systems, diving suits (Wet, Dry & Semi-dry suits are used depending on the water temperature) and buoyancy compensators can be used to adjust the overall buoyancy. When divers want to remain at constant depth, they try to achieve neutral buoyancy. This minimizes gas consumption caused by swimming to maintain depth.

The downward force on the diver is the weight of the diver and his equipment minus the weight of the same volume of the liquid that he is displacing; if the result is negative, that force is upwards. Diving weighting systems can be used to reduce the diver’s weight and cause an ascent in an emergency. Diving suits, mostly being made of compressible materials, shrink as the diver descends, and expand as the diver ascends, creating buoyancy changes. The diver can inject air into some diving suits to counteract the compression effect and squeeze. Buoyancy compensators allow easy and fine adjustments in the diver’s overall volume and therefore buoyancy. For open circuit divers, changes in the diver’s lung volume can be used to adjust buoyancy.

Avoiding losing body heat

Dry suit for reducing exposure

Main article: Diving suit

Water conducts heat from the diver 25 times better than air, which can lead to hypothermia even in mild water temperatures. Symptoms of hypothermia include impaired judgment and dexterity, which can quickly become deadly in an aquatic environment. In all but the warmest waters, divers need the thermal insulation provided by wetsuits or drysuits.

In the case of a wetsuit, the suit is designed to minimize heat loss. Wetsuits are generally made of neoprene that has small gas cells, generally nitrogen, trapped in it during the manufacturing process. The poor thermal conductivity of this expanded cell neoprene means that wetsuits reduce loss of body heat by conduction to the surrounding water. The neoprene in this case acts as an insulator.

The second way in which wetsuits reduce heat loss is to trap a thin layer of water between the diver’s skin and the insulating suit itself. Body heat then heats the trapped water. Provided the wetsuit is reasonably well-sealed at all openings (neck, wrists, legs), this reduces water flow over the surface of the skin, reducing loss of body heat by convection, and therefore keeps the diver warm (this is the principle employed in the use of a “Semi-Dry”)

Spring suit and steamer

In the case of a drysuit, it does exactly that: keeps a diver dry. The suit is sealed so that frigid water cannot penetrate the suit. Drysuit undergarments are often worn under a drysuit as well, and help to keep layers of air inside the suit for better thermal insulation. Some divers carry an extra gas bottle dedicated to filling the dry suit. Usually this bottle contains argon gas, because of its better insulation as compared with air.

Drysuits fall into two main categories neoprene and membrane; both systems have their good and bad points but generally their thermal properties can be reduced to:

Membrane: usually a trilaminate construction; owing to the thinness of the material (around 1 mm), these require an undersuit, usually of high insulation value if diving in cooler water.

Neoprene: a similar construction to wetsuits; these are often considerably thicker (78 mm) and have sufficient insulation to allow a lighter-weight undersuit (or none at all); however on deeper dives the neoprene can compress to as little as 2 mm thus losing a proportion of their insulation. Compressed or crushed neoprene may also be used (where the neoprene is pre-compressed to 23 mm) which avoids the variation of insulating properties with depth.

Avoiding skin cuts and grazes

Diving suits also help prevent the diver’s skin being damaged by rough or sharp underwater objects, marine animals or coral.

Diving longer and deeper safely

There are a number of techniques to increase the diver’s ability to dive deeper and longer:

Technical diving diving deeper than 40 metres (130 ft), using mixed gases, and/or entering overhead environments (caves or wrecks)

surface supplied diving use of umbilical gas supply and diving helmets.

saturation diving long-term use of underwater habitats under pressure and a gradual release of pressure over several days in a decompression chamber at the end of a dive.

Being mobile underwater

The diver needs to be mobile underwater. Streamlining dive gear will reduce drag and improve mobility. Personal mobility is enhanced by swimfins and Diver Propulsion Vehicles. Other equipment to improve mobility includes diving bells and diving shots.

Scuba dive training and certification agencies

Main article: List of diver training organizations

Diving lessons in Monterey Bay, California

Recreational scuba diving does not have a centralized certifying or regulatory agency, and is mostly self regulated. There are, however, several large diving organizations that train and certify divers and dive instructors, and many diving related sales and rental outlets require proof of diver certification from one of these organizations prior to selling or renting certain diving products or services.

The largest international certification agencies that are currently recognized by most diving outlets for diver certification include:

American Canadian Underwater Certifications (ACUC) (formerly Association of Canadian Underwater Councils) originated in Canada in 1969 and expanded internationally in 1984

British Sub Aqua Club (BSAC) based in the United Kingdom, founded in 1953 and is the largest dive club in the world

European Committee of Professional Diving Instructors (CEDIP) based in Europe since 1992 (see Cedip on French Wiki pages)

Confdration Mondiale des Activits Subaquatiques (CMAS), the World Underwater Federation

National Association of Underwater Instructors (NAUI) based in the United States

Professional Diving Instructors Corporation (PDIC) based in the United States

Professional Association of Diving Instructors (PADI) based in the United States, largest recreational dive training and certification organization in the world

Scottish Sub Aqua Club (SSAC or ScotSAC) the National Governing Body for the sport of diving in Scotland.

International Training SDI, TDI & ERDi -based in the United States, TDI is the world’s largest technical diving agency, SDI is the recreational division focusing on new methods and online courses, and ERDi is the public safety component.

Scuba Schools International (SSI) based in the United States with 35 Regional Centers and Area Offices around the globe.

YMCA scuba based in the U.S., part of Young Men’s Christian Association (YMCA), a Christian related organization (open to all faiths, ages and genders despite the historic name)

See also

Altitude diving

Aqualung, a type of breathing set

Aquanaut

Barodontalgia

Barotrauma

British Sub-Aqua Club

Coral Cay Conservation

Decompression sickness

Diver training

Divers Alert Network (DAN)

Diving equipment

Diving hazards and precautions

Diving physics

Diving signal

Diving suit

Drift diving

Engineer Diver

Like-A-Fish, a breathing set that extracts oxygen from surrounding water

scuba diving quarry

Sea Hunt, a television fiction series about scuba diving

Sea Trek

Snorkeling

Snuba

Technical diving

Timeline of underwater technology

Underwater diving

Underwater photography

Underwater videography

Wreck diving

Reference list

Scuba diving, grouped

^ “Compact Oxford English Dictionary – scuba”. Oxford University Press. http://www.askoxford.com/concise_oed/scuba?view=uk. 

^ a b c d e f g h i j US Navy Diving Manual, 6th revision. United States: US Naval Sea Systems Command. 2006. http://www.supsalv.org/00c3_publications.asp?destPage=00c3&pageID=3.9. Retrieved 2008-04-24. 

^ a b c d e f g h i j k Brubakk, Alf O; Neuman, Tom S (2003). Bennett and Elliott’s physiology and medicine of diving, 5th Rev ed. United States: Saunders Ltd. p. 800. ISBN 0702025712. 

^ Vann RD (2004). “Lambertsen and O2: beginnings of operational physiology”. Undersea Hyperb Med 31 (1): 2131. PMID 15233157. http://archive.rubicon-foundation.org/3987. Retrieved 2008-04-25. 

^ Butler FK (2004). “Closed-circuit oxygen diving in the U.S. Navy”. Undersea Hyperb Med 31 (1): 320. PMID 15233156. http://archive.rubicon-foundation.org/3986. Retrieved 2008-04-25. 

^ Hirschl, RB; et al (1995). “Liquid ventilatory in adults, children, and full-term neonates”. Lancet 346: 12011202. doi:10.1016/S0140-6736(95)92903-7. 

^ Sekins, KM; et al (1999). “Recent innovation in total liquid ventilation system and component design”. Biomedical instrumentation and technology 33: 277284. PMID 10360218. 

^ a b Richardson, D; Menduno, M; Shreeves, K. (eds). (1996). “Proceedings of Rebreather Forum 2.0.”. Diving Science and Technology Workshop.: 286. http://archive.rubicon-foundation.org/7555. Retrieved 2008-08-20. 

^ Hesser, CM; Fagraeus, L; Adolfson, J (1978). “Roles of nitrogen, oxygen, and carbon dioxide in compressed-air narcosis.”. Undersea Biomed. Res. 5 (4): 391400. ISSN 0093-5387. OCLC 2068005. PMID 734806. http://archive.rubicon-foundation.org/2810. Retrieved 2008-04-08. 

^ Brubakk, Alf O; Neuman, Tom S (2003). Bennett and Elliott’s physiology and medicine of diving, 5th Rev ed. United States: Saunders Ltd. p. 304. ISBN 0702025712. 

^ Deaths During Skin and Scuba Diving in California in 1970

^ Is recreational diving safe?, por Ikeda, T y Ashida, H

^ Longphre, J. M.; P. J. DeNoble; R. E. Moon; R. D. Vann; J. J. Freiberger (2007). “First aid normobaric oxygen for the treatment of recreational diving injuries”. Undersea Hyperb Med. 34 (1): 4349. ISSN 1066-2936. OCLC 26915585. PMID 17393938. http://archive.rubicon-foundation.org/5514. Retrieved 2008-05-03. 

^ NOAA Diving Manual, 4th Edition, Best Publishing, 2001

^ “Thermal Conductivity”, Georgia State University, accessed 15 February 2008

^ Weinberg, R. P.; E. D. Thalmann. (1990). “Effects of Hand and Foot Heating on Diver Thermal Balance”. Naval Medical Research Institute Report 90-52. http://archive.rubicon-foundation.org/4247. Retrieved 2008-05-03. 

^ Nuckols ML, Giblo J, Wood-Putnam JL. (September 1518, 2008). “Thermal Characteristics of Diving Garments When Using Argon as a Suit Inflation Gas.”. Proceedings of the Oceans 08 MTS/IEEE Quebec, Canada Meeting (MTS/IEEE). http://archive.rubicon-foundation.org/7962. Retrieved 2009-04-17. 

Further reading

Books published by the British Sub-Aqua Club:

The Diving Manual, BSAC, ISBN 0-9538919-2-5

Dive Leading, BSAC, ISBN 0-9538919-4-1

The Club 1953-2003, BSAC, ISBN 0-9538919-5-X

Free Scuba textbook by George D. Campbell, III called Diving With Deep-Six

External links

Divers Alert Networkiving Emergencies/Hyperbaric Chamber Assistance

Scuba diving travel guide from Wikitravel

Divemaster.com large forum and news and information site

Skaphandrus.comnline Scuba Diving Information

v  d  e

Underwater diving

Types:

Scuba diving  Surface supplied diving  Free-diving  Snorkelling  Saturation diving

Specialities:

Technical diving  Deep diving  Decompression diving  Mixed gas diving  Wreck diving  Cave diving  Ice diving  Rebreather diving  Solo diving  Altitude diving

Equipment:

Diving suit  Scuba set  Rebreather  Dive computer  Diver propulsion vehicle  Mask  Fins  Snorkel  Buoyancy control device

Disciplines:

Professional diving  Police diving  Military diving  Underwater photography  Underwater videography

Hazards:

Decompression sickness  Nitrogen narcosis  Oxygen toxicity  Barotrauma  Hyperbaric medicine  Drowning  Shallow water blackout  Deep water blackout  High pressure nervous syndrome  Dysbaric osteonecrosis

Categories: Underwater diving | Mixed sports | B-Class Water sports articlesHidden categories: Wikipedia semi-protected pages | All articles with unsourced statements | Articles with unsourced statements from February 2009 | Articles lacking in-text citations from February 2008 | All articles lacking in-text citations