Mounting
All aluminium electrolytic capacitors incorporate a safety vent of some form in order to relieve build up of internal pressure due to gassing. For the smaller ranges, such as snap-in or solder pin types, this takes the form of a weakened area in the side or base of the can. For the larger, screw terminal types the vent is incorporated in the deck.

In all cases consideration must be given, when mounting the capacitor, to the operation of the vent under failure conditions. It is recommended that capacitors are always mounted with the safety vent uppermost, or in the upper part of the device. Should the vent operate the least amount of electrolyte will then be expelled.

It is worth noting that screw terminal capacitors may be mounted in any position so long as the vent can operate. The operational and parametric performance is totally unaffected by the physical orientation but should the vent operate with the capacitor mounted upside down then a few drops of electrolyte may be expelled.

Board mounting types are designed to be mounted by their terminals alone. Larger types may have dummy pins for extra rigidity. Screw terminal and tag ended types may be fixed with a base stud or suitable mounting clamp.

Adequate space should be allowed between components for cooling air to circulate, particularly when high ripple currents are being applied.

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Altitude and Low Air Pressure
All capacitors manufactured by BHC are hermetically sealed and should therefore suffer no electrolyte seepage even under vacuum conditions. Additionally the electrical parameters of capacitance, esr, impedance and leakage current will be unaffected.

If a capacitor is operated at altitude, however, the life will be affected slightly for two reasons. Convected heat loss will be reduced as the air density falls resulting in the capacitor running hotter with a consequent reduction in life.

As the air pressure drops the differential between the internal case pressure and external pressure increases. A complete vacuum would cause the internal pressure to rise by 15 psi (approx.). If maintained this would lead to increased vapour loss and give a slight reduction in life expectancy.

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