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ANALYSIS OPINION
alcohols in the fluid because of these problems. Tirdly, IPA is easily contaminated. Alcohol
has a property of being ‘infinitely hygroscopic’ which means it likes water; it wants to absorb water. Tis property means that IPA in loosely sealed bottles in the back of a truck will absorb moisture from the air along with any contamination that resides in the air. Tis is why IPA oſten leaves a ‘water-mark’ residue on the connector end-face. Tese residues can ‘burn’ into the surface of the glass and increase the signal loss of the connector permanently, requiring time-consuming re-termination. Lastly, alcohol is flammable. It cannot be
carried on to an airplane nor easily shipped without hazmat paperwork and fees. Tis means that technicians, installing and repairing fibre links in remote locations, oſten have to leave their cleaning fluid at home. Becoming aware of the problems of alcohol, its
use discontinued and dry cleaning was adopted. However, that has been proven to be less than desirable. Wiping dry on a fibre end-face will generate a static charge (technically known as a ‘triboelectric charge’), which is extremely difficult to dissipate. Tis static charge turns the end-face into a microscopic magnet, attracting dust out of the air on to the heart of the end-face. Triboeclectric charging will occur when
rubbing any nonconductive surface with any dry wipe, such as a ‘Cletop’ or a fabric wipe. Te build-up of this ‘static’ charge on a connector end-face will attract unwanted airborne particulate and dust to the connector end-face. Te condition will be exacerbated in dry conditions (low humidity) such as winter cold or desert heat.
Importance of cleanliness With data rates over fibre only increasing, the need to clean properly has never been more important. A modern, water-free, high-purity fluid engineered for cleaning fibre optic connectors will both dissipate, and at least temporarily prevent, this build-up of triboelectric charges in the connector end-face. Terefore solvents should play an import role in cleaning. During the wet/dry cleaning process, a section
of the cleaning wipe is dampened with the cleaning fluid. Te connector end-face is wiped, usually moving from the damp area towards the dry area of the cleaning material. (In the case of port cleaning sticks or automated devices, a cleaning stick or device is dampened with a solvent and used to clean the end-face.) When a fast-drying, static-dissipative fluid is used with a wipe or highly absorbent cleaning stick, no
Mike Jones
drying step is necessary. Tis saves time, money and cleaning supplies. When selecting a fibre optic cleaning fluid,
there are several factors that should be considered. Te first consideration is whether the solvent readily removes a wide variety of soils and unwanted contaminates. Also, the user should make sure that the fluid is compatible with the wiping material or cleaning swabs. For example, one would not want to pair a solvent with a swab or wipe which was constructed of a material that the liquid would dissolve. Te second consideration is the safety of the solvent. Is the cleaning fluid flammable? Is the
onto the connector end-face spreading contamination. Very fast drying solvents will not remain in the liquid state long enough to become trapped within an alignment sleeve. Another consideration is the packaging of the
fluid. Te ideal packaging will prevent spillage, prevent re-contamination of the fluid during storage and normal use, and only dispense in quantities that are well-suited for a single cleaning. Te fluid should be safe to use over a wide temperature range and should not freeze in field applications. Spilling is another worry; it can be costly and dangerous, particularly in the case of flammable liquids. Open containers or pump-type dispensers can easily be contaminated from wipes, airborne contaminates or by refilling with unapproved fluids. Metered pumps are the ideal dispenser since the user cannot ‘over apply’ a solvent. Consider also materials compatibility. A
well-engineered fluid will be compatible and safe to use with a wide range of materials including optics, plastics, metals, elastomers, electronic assemblies and adhesives. A proper cleaning fluid will dry without residue, and will not create damage or alter the connector end-face, its housing, or surrounding associated equipment. Te environmental impact of the fluid is
Users will need new cleaning fluids in data centres, telco central offices, cable TV head- ends, and out in the field
cleaning fluid safe for technicians to handle? Can it be shipped as a non-hazardous material? Will it freeze? Is it safe for the environment? Te answers will be found on the product spec sheet and the MSDS sheet for the cleaning fluid.
Speed is of the essence Another consideration is the speed of drying of the solvent: faster is better. Slower drying solvents require more time or more wiping to dry (which can delay progress, and also contribute to static charge build-up). But more importantly, slower drying solvents can ‘hang’ in the split of the alignment sleeve of an adaptor or optical port of device. Te trapped liquid, can then weep back
important as well. Te US Government has four classifications of chemicals affecting air quality and the environment. Te classifications are VOCs (volatile organic compounds), ODPs (ozone depleting pollutants), HAPs (hazardous air pollutants), and lastly GWP (global warming potential). In general, most fluids cannot be positive in all four categories. For example, if a material is not a VOC then it probably has a higher global warming classification. Te best recommendation is to select the safest solvent that will satisfactorily perform the cleaning task and the best packaging to utilise as little fluid as possible. Lastly, one must consider the cost, which must
include the cost of the solvent, the safe storage and transport of the solvent, and the packaging of the solvent (the likely amount of solvent used per clean). In conclusion, users will need new cleaning
fluids in data centres, telco central offices, cable TV head-ends, and out in the field to clean today’s fibre optic connectors. Tere are many considerations that must be taken into account to provide the best product for the user. Price per can or bottle alone does not reflect the real cost. We all have responsibilities to provide for the user with a fluid and a package that is safe, convenient, reliable and environmentally responsible.l
Issue 5 • Autumn 2014 FIBRE SYSTEMS 17
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