Cylinders are made out of two types of material: steel and aluminum (actually an aluminum alloy). Each have different properties that make it appealing for different types of construction and use. Steel cylinders are tough, making them resistant to damage. They also tend to support higher capacities, because of their increased strength.
A Brief Scuba Cylinder History
Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. Nitrox Scuba Tanks There are two basic types of breathing gases available to the sport scuba divers. Normal Air – Air is taken through a filtration system and then pumped under pressure into your scuba tank.Always purchase your air fills from a Certified Pure Air Station. Diving cylinders are made in two types: Aluminum tanks and Steel tanks. There's not much difference between the two other than the obvious fact that they are made out of different metals. Aluminum tanks are the most common in the world and since they are more cost efficient, especially compared to steel tanks, they can be found at almost any. A diving cylinder, scuba tank or diving tank is a gas cylinder used to store and transport the high pressure breathing gas required by a scuba set.It may also be used for surface-supplied diving or as decompression gas or an emergency gas supply for surface supplied diving or scuba. Cylinders provide gas to the diver through the demand valve of a diving regulator or the breathing loop of a.
- Created on Monday, August 15 2011 09:03
- Written by Bill High, Founder, PSI-PCI, Inc.
A Brief Scuba Cylinder History
By
Bill High
PSI-PCI, Inc.
The first non-military scuba system arrived in the U.S.A. in 1949.Within months, a small group of scuba divers emerged from among geology, oceanography and biology students at Scripps Institute of Oceanography, La Jolla, California.
Throughout the 1950's and early 1960's, several steel cylinder sizes were marketed having pressures ranging from 2,150 psig to 3,000 psig. Between 1958 and 1960, valves changed from mostly 1/2 inch tapered thread to 3/4 inch, 14 turns to the inch straight thread with O-ring.However, there were some 1/2 inch straight threaded cylinders as well.In the late 1980's, the DIN valve was introduced into the U.S. from Europe for use with cylinders rated above 3,000 psig.Only steel cylinders were authorized for commercial service until late 1971.
Most early commercial steel scuba cylinders ranged in volume from about 65 cuft to 95 cuft.However, many surplus World War II era 38 cuft cylinders with a service pressure of 1,800 psig were used, commonly as doubles.Some '38's' still pass their quality assurance tests and remain in service today.
The U.S. manufacturers of steel scuba cylinders included Pressed Steel Tank Co. (PST), Norris Industries, and Walter Kidde Co.The Italian firm Faber makes U.S. Department of Transportation (DOT) approved cylinders sold until recently under several brand names. Currently Faber cylinders are distributed by the Blue Steel Company.In the early 1990's, Heiser manufactured steel cylinders under the brand name Beauchat for sale in the U.S.Because of excessive weight, these cylinders were not popular. In 2004 Worthington, a Canadian company began distributing its steel cylinders under several brand names.
By the mid 1950's, PST and one other company began making aluminum cylinders from 6061 alloy for the U.S. Navy.The fabrication process was very different from the way aluminum cylinders are made today.Those round bottom aluminum cylinders are illegal for most purposes U.S. because they have no DOT designation. They must not be hydrostatic retested and not filled at commercial air stations.
Newly formed Luxfer USA, Ltd. (in 1997 the company name was changed to Luxfer Gas Cylinders), with DOT special permit SP6498, began producing aluminum cylinders in late 1971.Using 6351 alloy in a cold extrusion process, the cylinder did not require a bottom plug as did the former military type.The Luxfer approved cylinder had a flat bottom, as are all aluminum scuba cylinders made today.In order to be equivalent to the then popular steel cylinders, Luxfer made its cylinder 6.8 inches in diameter to fit existing non-adjustable backpacks and with a similar 2,475 psig service pressure.To achieve the 72 cuft capacity, the Luxfer cylinder was made longer but, as a consequence, it was about 11 pounds buoyant when near empty.Divers quickly named it the 'floater'.
Walter Kidde (with special permit SP7042), Norris Industries(SP6688) and Kaiser (SP6576) followed Luxfer into the aluminum cylinder business during the early 1970's.The Kaiser cylinder (brand name AMF) has a 2,700 psig service pressure and a somewhat rounded (beveled) bottom.
Luxfer and Walter Kidde continued production under their DOT SP6498, E6498 or SP7042, E7042 until the DOT formalized the aluminum cylinder category 3AL in July 1982.Unfortunately for owners of Norris Industries SP6688 and Kaiser SP6576, BOTH CYLINDERS must be removed from service in the US as those permits expired by 1979. A special grandfather clause allows their use in Canada.Like the illegal navy surplus aluminum cylinders, many SP6688 and SP 6576 cylinders are used in the US
Clc workbench price. because hydro retesters, fill station operators and owners ignore or are ignorant of theirstatus.
The Catalina Tank Co. (now called Catalina Cylinders) began manufacturing 3AL cylinders in 1986 using 6061 alloy.Luxfer switched completely to the 6061 alloy by June, 1988 while Walter Kidde continued using alloy 6351 until production ceased in July, 1989.Today, only Luxfer Gas Cylinders and Catalina Cylinders produce 3AL scuba cylinders for sale in the US and much of the world.In the early 1990's, Parker produced a few aluminum scuba cylinders.
PST created renewed interest in steel cylinders by introducing high-density 3,500 psig steel E9791 cylinders in 1987.Those cylinders were sold by Sherwood (Genesis) and U.S. Divers Co. (HP3.5).By 1998, that cylinder type was distributed in several volumes by other companies.In 2004 PST introduced an E series cylinder in both 2,400 psig and 3442 psig.
Coyne cylinders joined the steel scuba business in 1993, producing a limited number of 2,400 psig cylinders in several sizes.Coyne, a subsidiary of Taylor-Wharton is not manufacturing scuba cylinders in 2001.
Two other cylinder types attracted much interest in the diving community.About 1986, Dacor demonstrated a stainless steel scuba cylinder at the DEMA trade show.It was an attractive cylinder that boasted many advantages over other metals.However, no DOT approved cylinders were ever produced including the models shown at the trade show.About 1990, two Russian titanium cylinders were demonstrated at the DEMA show.Their pressure rating exceeded 6,000 psig.However, because titanium cylinders require welding, DOT approval was difficult to acquire as high-pressure DOT cylinders must be seamless.Titanium cylinders are now produced in Russia and sold by a U.S. company to international military units.Although heavier than common scuba cylinders, those cylinders have exceptional capacity when compressors are available to achieve the high rated pressure.
Readers interested in more scuba cylinder history and safety should read Inspecting Cylinders-5th Edition available from PSI-PCI, Inc.Other cylinder articles appear on the web site, psicylinders.com. You may contact PSI-PCI at This e-mail address is being protected from spambots. You need JavaScript enabled to view it. or 425-398-4300 with questions.
One of the most overlooked aspect by most divers is how their scuba tanks are made. However, they have to pay attention to this because it affects diving in one way or another. Also, it always pays to know some bits of information about the equipment you are diving with.
Comparison
Want to know the difference between the two? Check out this quick comparison list.
Material – Generally speaking, tanks are made of two materials: aluminum alloy and steel. But there is a recent addition in the form of carbon tanks. Each has varying properties and features that make it ideal for a particular purpose. As you might have guessed, aluminum alloy is much softer than stainless steel. While softer, they work as well for general use. The walls within, however, is thicker than that of steel. Because of this, aluminum tanks are generally heavier than those made of steel. The downside of aluminum? It doesn't handle overfilling well. Steel, on the other hand, is tough and damage-resistant. They also support higher capacities compared to aluminum. However, it can rust without proper maintenance. Finally carbon's material is amazingly strong, yet extremely light in terms of weight. However, carbon fiber tanks are pricier than the first two.
Identification – Unless you're doing metalwork for a living, it's quite a challenge distinguishing which tank is made from steel or aluminum. Good thing these days, some states require stamping of information on dive tanks, including its construction and material. However, the stamps use some form of codes, which you must learn to read. For example, it the tank says '3AL' your cylinder is crafted from aluminum alloy. If it's '3AA', then your tank is made from steel. Carbon fiber tanks are marked with '3FCM'.
Buoyancy – The type of cylinder you use has an effect on your buoyancy. Steel tanks are less buoyant than aluminum, thus you will need less weight when diving with one. When using aluminum, it is the other way around. Carbon fiber tanks are usually lighter than steel. As a general rule, you have to add about 5 pounds per 2 kg to your weight base when you're using an aluminum tank.
Top Picks on Scuba Tanks
Luxfer Compact Aluminum 80 CF Tank
With maximum fill pressure of 3300 PSI, this 80-cubic feet tank is a favorite choice among modern divers. When empty, it weighs 34.7 pounds. This tank is designed to maintain a bit of negative buoyancy underwater, even when there is no air inside. Luxfer is industrial strength aluminum alloy. According to customers, the tank can be used not only for scuba diving, but also as filling source for PCP air rifles. When it comes to price, this 80CF tank beats others with the same 3300 PSI.
Faber FX High Pressure Steel 100 CF Tank
This tank makes an excellent choice for divers looking for a durable high pressure steel tank. It has DOT E-13488 specification, meaning overfilling is not allowed. Maximum fill pressure is 3442 psi, and weighs 34.3 pounds when no valve is attached. Every package comes with a valve and tank boot. Customers say that it is an awesome scuba tank to invest on. Compared to aluminum tank, its buoyancy and weight distribution is pretty sufficient. And, even after 50 diving sessions, the tank looks good as new.
Cyl-Tec 80cf Scuba Diving Tank
Having the most popular size of a dive cylinder, Cyl-Tec's 80 CF scuba tank is built from high strength aluminum alloy. The tank is designed following the standards of US Department of Transportation. Package comes with a new combo valve. Based on customer feedbacks, this scuba tank is of good quality, and comes with protective plastic webbing on the surface. Other than scuba diving, the 80CF works well for compressed air applications or paintballs.
What Two Metals Are Scuba Tanks Commonly Made From Atoms
Sherwood Aluminum 100CF Scuba Diving Tank
What Two Metals Are Scuba Tanks Commonly Made From Recycled
Sherwood's high quality tanks are trusted by divers for years. Maximum fill pressure is 3300 PSI. Capacity, on the other hand, is up to 100CF. It weighs a total of 46.2 pounds, and comes in three different colors including black, yellow, and no paint. According to user reviews the diving tank is perfect, hydro tested, and offers a great deal for all sorts of divers out there.
What 2 Metals Are Scuba Tanks Made From
How you choose your tanks has an impact on your diving sessions. Therefore, it's required that you pay extra attention to the type of tanks that suit your diving environment and personal specifications. After all, your oxygen source will go through it so choosing the finest one there is must be of great priority. Aside from the type of scuba tank, it is also important that you select its accessories accordingly. Valves, O-rings, and carriers are just some of the attachments you want to consider purchasing.
