Scuba Cylinder Care
Care and Storage of Aluminium and Steel Dive Tanks
How To Take Good Care Of Your Dive Cylinder
Although scuba cylinders have been designed to exceed stringent performance and safety standards, it's up to you to ensure that your cylinder is always kept in peak condition by carefully following these recommendations for continued care and maintenance.
By taking care of your cylinder you'll be rewarded with many years of safe, trouble-free service. Protect it from damage and never abuse or modify it. Neglecting the cylinder could result in irreversible deterioration and a potential threat to personal safety. Wash your cylinder in fresh water and dry after each use.
For New Scuba Cylinders
- Ensure that your cylinder is fitted with a compatible valve and associated components. Putting the wrong valve on a scuba tank can result in a very explosive and potentially deadly situation.
- When using oxygen-enriched air, oxygen or nitrox mixtures, ensure that the cylinder is fitted with an oxygen or nitrox-compatible valve assembled with an oxygen compatible O-ring and lubricant. If your cylinder is Oxygen Clean then it should be marked as such with an appropriate sticker.
- Establish that the filling facility is suitable for providing a controlled oxygen-enriched air-fill, which must be totally free from oil carry-over and loose particulate, such as at O2ToGo Dive Centre.
- If there's no assurance that the valve, O-ring and lubricant used is oxygen compatible, or that the filling conditions conform, O2ToGo Dive Centre recommend that you don't fill the cylinder until oxygen suitability is confirmed.
- If you choose a standard air-fill only but decide to switch to an oxygen-enrich fill at a later date, remember to ensure that your cylinder is oxygen clean and that your valve and associated accessories are oxygen compatible and clean.
For Continued Use of the Scuba Cylinder
- Check that the cylinder is within its re-test period. In Canada, a visual inspection is required to be done annually and a hydro testing is required a minimum of once every 5 years. Cylinders should be stamped with the test centre number plus the month and year they were last tested, e.g. 01 18 (Jan 2018). This example means the cylinder can be filled until the end of January 2018 before having to be tested again.
- NEVER fill a cylinder that's outside its re-test period.
- Visually examine the cylinder for evidence of damage from previous use or transportation. If in doubt (i.e. the cylinder shows signs of ANY damage) take it to a re-test station, like O2ToGo Dive Centre, for an expert opinion and/or hydro testing.
- Determine if the cylinder shows external corrosion from poor storage, particularly after lengthy storage. If corrosion is evident, take the cylinder to a re-test station, like O2ToGo Dive Centre, for an expert opinion and/or hydro-testing.
- An appropriate valve (with the correct thread) should be torqued into the cylinder using calibrated torque wrenches with correctly fitting engagement heads.
Filling Scuba Cylinders
- Before you connect the cylinder to the compressor or storage bank ALWAYS verify the rated filling pressure.
- NEVER fill the cylinder or allow it to be filled beyond the maximum rated working pressure (WP) shown on the cylinder neck.
- If you suspect or hear a hissing sound — stop filling immediately. NEVER fill or use a cylinder that is leaking. The cylinder must be taken to an approved re-test station, like O2ToGo Dive Centre, for a thorough examination. Never try to tighten the valve if leaking around the cylinder neck.
- ALWAYS check for leaks after filling and before use by immersing the cylinder into a tank or container of water. Take enough time to thoroughly check for even the smallest escaping bubble!
It is strongly recommended that extreme care is taken to avoid any moisture transfer into your diving cylinder.
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How To Safely Move Dive Cylinders
Keep your cylinder in top condition by following these common-sense guidelines:
- Fit suitable protective valve caps and covers to cylinders, when necessary, before transporting. Caps and covers help prevent moisture and dirt from gathering in the valve of the cylinder, in addition to providing protection during transport. See Cylinder Accessories / Parts for some of the products available from O2ToGo Dive Centre.
Trident Rubber DIN/Yoke Valve Cap Protector Cover
Our Price: $5.00
Keep one of these protective covers on the top of your cylinder/tank Yoke valve to prevent loss of your O-ring and keep debris out of the valve when not in use.
Trident Male DIN Valve Cover Plug - Machined Delrin
Our Price: $11.00
Works with either 200-bar or 300-bar DIN valves to protect your scuba diving cylinder/tank valve from dust and debris.
Always secure your cylinder safely when in transit.
Tank Holder - Foam Triple Cylinder Holder
Our Price: $43.95
This lightweight cylinder holder design works great in car trunks, trucks, and boats. It will hold three of most tanks and stop them from rolling around.
- Prevent the cylinder from rolling about — any impact could damage the shell by indenting, scratching, gouging, scoring or chipping off protective paint finishes.
- Do NOT throw the cylinder onto sand or ground — it may impact against a hidden hard object that could cause damage.
- Take care to avoid dropping your cylinder — as well as damaging an empty cylinder, dropping a charged cylinder could shear the valve.
Prevent the cylinder from being exposed to direct sunlight or where the sun is directed through windows or clear glass roofing.
- Keep your cylinder cool. Filled cylinders that become warm (up to 60°C) could result in breathing difficulties due to the temperature of the contained gas. Never expose your cylinder to temperatures in excess of 60°C.
Consider adding a sturdy tank handle to you steel scuba cylinder. These make carrying and handling heavy dive cylinders much easier and safer.
Trident Dive Cylinder Tank Carry Handle - Standard
Our Price: $30.00
Safe and easy carrying of aluminum and steel dive cylinders. Fits tanks up to 8" diameter.
How To Clean Scuba Cylinders After Diving
- Do not leave cylinder valves open after use. This allows moist-air intake that can cause internal corrosion.
- After use, thoroughly wash the outside and boot assembly with clean water containing mild soap or detergent, rinse off and wipe dry with a towel.
- It is advisable to regularly remove the cylinder from its backpack and the boot for a more thorough cleaning.
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How To Store Scuba Diving Cylinders Safely
Safe storage for scuba cylinders is often neglected.
- ALWAYS ensure your cylinder maintains a slight positive pressure of around 300 psi (20 bar).
- NEVER store the cylinder on bare concrete, or any surface that may hold moisture.
Short Term Storage
- For short term storage, the cylinders can be stored full.
Long Term Storage
- Long term storage is defined as more than 90 days. For long term storage, the cylinder should contain less than or equal to 300 psi (20 bar). This is what some of the cylinder manufactures recommend. Some others say it should be less than or equal to 50 psi (3 bar). However, scuba surface pressure gauges (SPGs) often don't read this low, therefore you'd maybe use the first measure on your SPG.
Note: A cylinder expands every time it is filled and contracts when emptied. Repeated expansion and contraction fatigues the metal and eventually it will fail. (This is why we do hydro testing every 5 years, to detect cylinders that no longer tolerate repeated expansion/retraction.) So, it is best to store cylinders nearly empty to reduce metal fatigue.
- Oxidation of the metal cylinder is directly proportional to oxygen content, or the partial pressure of oxygen. Therefore cylinders should be stored almost empty to minimise the partial pressure of oxygen and corrosion.
- In steel cylinders, oxidation of the steel consumes oxygen in the breathing gas and has been shown to dramatically reduce the oxygen content of the gas in certain situations. Therefore, steel cylinders should be stored nearly empty so that they must be filled with fresh gas before use. Alternatively, the gas in a steel cylinder must be tested for oxygen content after long-term storage.
- Cylinders should be stored vertically and tightly secured to prevent them being knocked over.
Note: Small amounts of moisture inside of the cylinder cause corrosion. If the tank is stored on its side, the corrosion is spread across the thinner sidewall. If the tank is stored upright, the corrosion is focused on the thicker base. Thus cylinders should be stored upright.
- The ambient temperature should be less than 60°C (140°F).
- The storage of tanks should be well away from heat sources, including hot lights, heaters, furnaces, freezers, electrical or combustion motors.
- Keep the area dry and free from caustic chemicals. Trace vapours can cause corrosion!
- It is important to consider the storage area location and to keep the area protected from passersby.
- Oxygen cylinders must be stored at least 6 metres (20 feet) flammable gas containers or combustible materials such as oil or grease. Ideally they should be separated by a non-combustible barrier.
Scuba Cylinder Testing Check List
- ALWAYS ensure your cylinder is re-tested within the prescribed period. In Canada this is done every 5 years.
- ALWAYS ensure your cylinder has it's annual visual inspection.
- ALWAYS ensure that the cylinder attachments are maintained, serviced, inspected and handled in strict accordance with the manufacturers instructions.
Of course, O2ToGo Dive Centre can do your annual Scuba Cylinder Testing.
Repair of Scuba Cylinders
- If the painted surface is damaged do not ignore it! Clean the area with fine wire wool and touch up the damage with a room-temperature air-drying primer followed by a room temperature drying gloss paint. Do not use paints with a curing temperature above ambient. For further information contact the cylinder manufacturer.
- Do not attempt to remove a damaged paint surface with abrasive wheels, files, shot-blasting or aggressive chemicals. This may reduce the wall thickness making the cylinder unsafe for pressure storage.
- If using stainless steel fixtures as a backpack clamp on bare aluminium cylinders — coat with a suitable plastic to insulate from the aluminium.
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How To Read Scuba Cylinder Markings
- NEVER alter or obscure the cylinder markings!
- NEVER fill or partially fill your cylinder with Oxygen, Oxygen mixtures or Nitrox unless the cylinder and valve have been properly cleaned and maintained for these mixtures!
- The markings stamped on the neck of your cylinder contain important information which should be referred to when re-testing or filling.
Typical markings include:
How To Clean The Exterior Of Aluminium Scuba Cylinders
- Aluminum cylinders in normal service, particularly those having a brushed finish, can pick up grime and scuffing which altar the appearance. There are a variety of commercial aluminum cleaners available which can be used to clean and improve this appearance. Please make certain that the product used is specifically marked "suitable for aluminum." Otherwise, serious damage could occur resulting in reduction in wall thickness and inherent strength.
The following methods of cleaning, or combinations thereof, are also acceptable:
- Soap and water
- Solvent wipe
- Non-metallic scrubbing pads
Do not use solvent wipes or non-metallic scrubbing pads on painted/clear-coated cylinders! Use only solvents suitable for painted surfaces.
- Label removal from the coated surface of an aluminium cylinder should be done so as to not disturb or ruin the coating of the aluminum cylinder. O2ToGo Dive Centre does not recommend the use of chemical label removers. A particularly good physical label removing tool can be useful.
How To Remove Paint From Aluminum Scuba Cylinders
- Some aluminum cylinders come painted. Unfortunately this paint soon starts coming off with flakes of paint ending up everywhere. Thus we are often asked how it can be removed.
- To remove paint from aluminum cylinders, NEVER use caustic paint strippers or acid paint strippers, burning techniques, or solvents that harm the environment or pose personal health or safety concerns. Any chemical used to remove paint from, or to paint a cylinder, should specifically say on the label that it is safe and recommended for use on aluminum surfaces.
- We recommend you use gel strippers to remove paint from cylinders. Gel strippers are brushed on the cylinder, allowed to stand, and then removed by a water rinse, typically under high pressure. In all cases, follow instructions and precautions when using strippers.