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Technical bulletins

Technical bulletins

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Dates of SCUBA cylinder aluminum alloy changes

Dates by models when Luxfer changed the aluminum alloy in its scuba tanks from 6351-T6 to Luxfer’s proprietary 6061-T6 alloy.

S808 - May 1987

S72 - August 1987

S100 - August 1987

S80 - January 1988

S50 - April 1988

S92 - April 1988

S30 - May 1988

S63 - May 1988

S40 - June 1988

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Temperature exposure

Luxfer Gas Cylinders strongly recommends that you make the following information available to any and all persons who handle and/or fill high-pressure aluminum gas cylinders:

You are warned that failure to strictly follow these guidelines could result in overheating of the cylinder which could weaken the cylinder, causing it to fail under pressure, exposing bystanders to serious injury or even death and/or loss of property.

WARNING:
  • Do not expose any aluminum cylinder to temperatures in excess of 265ºF (130ºC).
  • If you know or suspect an aluminum cylinder has been exposed to elevated temperatures BETWEEN 265ºF (130ºC) and 350ºF (175ºC), it MUST be hydrostatically retested before being returned to service.

Common evidence of exposure to elevated temperatures above 265ºF (130ºC) includes:

  • Charring or blistering of the paint or other protective coating
  • Distortion of the cylinder
  • Melting of fuse plugs
  • Charring or burning of labels
  • Increases in total or permanent expansion from hydrotesting
  • Distortion of valve or carrying handles
WARNING:
  • Any cylinder exposed to the direct action of fire MUST be removed from service as its mechanical properties are adversely affected by exposure to high temperatures (49 CFR 173.34) and it may fail under pressure.
  • Any aluminum cylinder exposed or suspected of having been exposed to temperatures in excess of 350º F (175ºC) MUST be condemned (CGA C-6.1) and removed from service.
  • If your cylinder has a heat-indicating clear coat, it must be condemned immediately if the coat changes to a brown color.

The properties of aluminum cylinders rapidly degrade or change when temperatures exceed 350ºF (175ºC). The longer the exposure the greater the degradation of the metal, which weakens and may later fail under pressure. The higher the temperature above 350ºF (175ºC), the faster and greater the degradation.

PAINTING RECOMMENDATION:

To avoid the risk of cylinder failure and risk to human life, Luxfer strongly recommends that cylinders should only be repainted using paints that cure and dry at room temperature. These paints may be water-based although some areas permit solvent paints (check with your local authorities). A clear coat, which also cures and dries at room temperature, may be applied over the new paint. Use only paints specifically recommended for use on aluminum surfaces.

WARNING:
  • Do not use caustic paint strippers or corrosive cleaners to remove paint from aluminum cylinders. They will damage the cylinder and weaken the metal which could later cause a failure under pressure.
  • Do not remove old paint by using blasting media that will or may remove metal from the cylinder.

If you have any questions regarding the above, contact Luxfer's Customer Service at (951) 684-5110. If you are a professional refinisher or repainter of aluminum cylinders, please contact Luxfer for a special technical bulletin on cylinder repainting.

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Paint strippers for aluminum cylinders

CAUTION

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.

If the entire cylinder is to be painted, please read the technical bulletin on Heat Exposure or contact Luxfer Gas Cylinders' Customer Service department for recommendations.

Luxfer recommends 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. "Zip Strip", produced by Star Bronze Company, is a satisfactory gel stripper. For more information, contact:

Star Bronze Company, 803 South Mahoning, Alliance, OH 44601. Phone: (216) 823-1550

In all cases, follow instructions and precautions when using strippers.

For more information, call Luxfer's Customer Service department at (951) 684-5110 or, if a scuba cylinder owner, see Luxfer's Guide to Scuba Cylinder Inspection.

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Cylinder OD cleaning procedure for brushed and unpainted cylinders

Aluminum cylinders in normal service, particularly those having a brushed finish, can pick up grime and scuffing which mar 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 a Luxfer cylinder should be done so as to not disturb or ruin the coating of the aluminum cylinder. Luxfer does not recommend the use of chemical label removers. A particularly good physical label removing tool (the Super Scraper) is available from Motsenbocker. Call (858) 581-0222 for your nearest supplier.

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Cylinder ID cleaning procedure

High-pressure cylinders in normal traffic can accumulate I.D. contamination which may detrimentally affect end use. The following procedures are recommended for I.D. cleaning of aluminum cylinders.

  • Moisture and grime.
  • Steam clean and blow dry.
Oil, grease, lubricants

Clean with a soapy solution - one tablespoon of liquid dish washing detergent to one gallon of tap water. Rinse several times with tap water, rinse twice with demineralized or soft water, steam clean and blow dry. Complete the process without a break. Never leave cylinder freestanding with water.

Odors

Rinse thoroughly with a solution of baking soda (one cup baking soda to one gallon of tap water). Rinse with clean tap water. Then, rinse with a solution of vinegar (one half cup of household vinegar to one gallon of clean tap water). Rinse several times with fresh tap water, rinse twice with soft water. Steam clean and blow dry. Complete the process without a break. Never leave cylinder freestanding with water.

Corrosion

Tumble the cylinder at 25 to 35 rpm for 10 minutes with a wet detergent aluminum oxide chip combination (two to three cups of aluminum oxide tumbling chips to two quarts of soft water and one teaspoon of liquid washing detergent). Rinse cylinder well with warm tap water (or soft water if the tap water is hard), steam clean and blow dry.

NOTE: Use demineralized water or make sure water is soft.

OBSERVE MANUFACTURERS' CAUTIONS FOR ALL PRODUCTS USED.

NOTE: Tumbling Media is available from Galiso Nuvac, 22 Ponderosa Ct., Montrose, CO 81402-1468, (800) 854-3789. For more information, call Luxfer's Customer Service department at (951) 684-5110 or, if a scuba cylinder owner, see Luxfer's Guide to Scuba Cylinder Inspection.