Dust Covers
Connector Caps Definition
Connector Dust Covers are used to protect the pins of connectors that are exposed when having no cable attached. Dust covers may be produced in either Plastic or Metal. Plastic dust covers are much cheaper than there more expensive metal counter-parts. Metal dust covers may also be made to shield against EMI issues. In addition many styles of metal dust covers also come with an attached chain which may be secured to the chassis. Using the chain insures that the dust cover is not dropped or lost when disconnected for cable attachment.
Either metal or plastic dust covers come in almost any connector shape, including D-Sub or circular connectors. Circular caps will press fit on in the case of plastic or screw on in the case of metal types. However there are Metal Slide-on Dust Covers that are available. While D-Sub miniature types will press fit on with either plastic or metal caps, but the metal will also use the locking screws on either side of the D-connector. Environmental Protection Rating.
| Alternate terms; |
Dust Cover Manufacturers
Anderson Power Products {Connector Dust Covers}
Caplugs {Plastic Caps and Plugs for connectors}
Sys Concept Inc. {Metal Dust Cap w/ Chain}
StockCap {Plastic Dust Caps, Hoods}
Unitrack Industries {Metal Dust Caps w/chains}
Fuse Holders is the next topic in Chassis Design.
Design Guideline; Protective measures. All unmated connectors should be protected with metal or plastic caps or otherwise suitably protected during maintenance, storage and shipment. Protective caps specified by military specifications or military standards and designed for mating with specific connectors should be used. Unmated connectors which may contain electrically "hot" circuits while in environmentally hazardous areas should be covered with moisture-proof and vapor-proof caps. Connectors on enclosed cabinet mounted equipment need not be provided with protective caps unless an environmental hazard exists. [Reference MIL-HDBK-454].
Connector Cap Details
Dust Cap Chain; Bead chain, Safety Chain, Rope chain, Lanyard.
Common chain lengths; 2.25 inches, 3.25 inches, 3.75 inches
Common Commercial lengths; 3, 5 and 6 inches
Chassis Attachment point, Eyelet ID; 0.144 inches, .17 inches, .281 inches, .5 inches, .52 inches .635 inches. End-Ring Assembly
Circular MIL Cover
Specifications and Standards
MIL-C-39012/25 Connectors, Coaxial, Radio frequency (Hardware for Radio frequency Coaxial Connectors);
MIL-PRF-39012 BNC Dust Cap [Slash Sheet 25]
M39012/25-0006 BNC Jack, bead
M39012/25-0007 BNC Jack, safety chain
M39012/25-0008 BNC plug, bead
M39012/25-0009 BNC plug, safety chain
MIL-W-83420 Wire Rope, Flexible, for Aircraft Control
MIL-DTL-83420 Galvanized steel wire rope
Type I - Nonjacketed wire rope
Type II - Jacketed wire rope [nylon jacketed]
MIL-PRF-28876/15; Connectors, Fiber Optic, Circular, Receptacle Style, Multiple Removable Termination, Dust Cover, Screw Threads, Environment Resisting
MIL-DTL-28840/15; Connectors, Electrical, Circular Threaded, High Shock, High Density, Shipboard, Dust Cover, Plug
MS17349E Cover, Protective, Electrical Connector, Receptacle Cover, Class L
Related Topic: EMI Issues with a Chassis
BNC Connector Cap, Metal Cover
Design Hint; A BNC Terminator will also act as a Dust Cap or EMI shield for the connector.
If a 50 ohm terminator is required, than spec out the termination instead of a standard dust cap.
Termination loads also come with attachment chains.
BNC Connector Caps
Example usage of connector covers. Note that all the chained protect caps are metal; however there are two purple plastic dust caps being used on this rear panel. Also that a few of the interfaces do not have metal caps attached to them. Normally if the equipment requires an interface to always be active in order for the equipment to function, then that connector will not require a protective cap because a cable will always be attached during operation. While the optional I/O will have an attached cover.
How To Specify a Equipment Chassis; Chassis Design Index page
