How do you clean connectors for testing?

With fiber optics, our tolerance to dirt is near zero. Airborne particles are about the size of the core of SM fiber and are ususlly silica based- they may scratch PC connectors if not removed! Test equipment that has fiber-bulkhead outputs need periodic cleaning, since they may have hundreds of insertions of test cables in short time frames. Here’s a summary of what we have learned.

1. Always keep protective “dust caps” on connectors, bulkhead splices, patch panels or anything else that is going to have a connection made with it. Dust caps themselves may contain dust so whenever a connector is to be used, clean it.
2. Use any of the commercial fiber optic cleaning kit to clean connectors and mating adapters. Alternatively, use fiber optic cleaning wipes and isoproply alcohol to clean the connectors. Some solvents MIGHT attack epoxy, so only pure alcohol should be used. Cotton swabs and cloth leave threads behind. Some optical cleaners leave residues. Residues usually attract dirt and make it stick.
3. All “canned air” has a liquid propellant. Years ago, you could buy a can of plain dry nitrogen to blow things out with, but it’s long gone. Today’s aerosol cleaners use non-CFC propellant and will leave a residue unless you 1. hold them perfectly level when spraying and 2. spray for 3-5 seconds before using to insure that any liquid propellant is expelled from the nozzle. These cans can be used to blow dust out of bulkheads with a connector in the other side or an active device mount (xmit/rcvr). NEVER use compressed air from a hose (they emit a fine spray of oil from the compressor!) or blow on them (you breath is full of moisture , not to mention all those yukky germs!)
4. A better way to clean these bulkheads is to remove both connectors and clean with fiber optic cleaning wipes, then use a fiber optic cleaning swabs made of the same material with alcohol on it to clean out the bulkhead.
5. Detectors on optical power meter should also be cleaned with the fiber optic cleaning wipesoccasionally to remove dirt. Take the connector adapter off and wipe the surface, then air dry.
6. Ferrules on the connectors/cables used for testing will get dirty by scraping off the material of the alignment sleeve in the splice bushing. Some of these sleeves are molded glass-filled thermoplastic and sold for multimode applications. These will give you a dirty connector ferrule in 10 insertions! You can see the front edge of the connector ferrule getting black! The alignment sleeve will build up an internal ledge and create a gap between the mating ferrules – viola: a 1-2 dB attenuator! Use the metal or ceramic alignment sleeve bulkheads only if you are expecting repeated insertions. Cleaning the above reguires agressive scrubbing on the ferrules with the fiber optic cleaning wipes and tossing the bulkhead away.
7. You can buy a fiber optic cleaning kit for fiber optics. They are good solutions but perhaps not as cost effective as making your own to meet your needs.

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