Air Supplies
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Fig. 22. A piston-type air pump for aquarium use. (Courtesy Medcalf Bros.)
convenient to use. as they require frequent lubrication, tend to conair supply with oil, and require a more complex piping
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system. The rotating component which_drives the pistons has a very
low torque or turning force, and so the pump can easily be stopped
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by any small back pressure in either piston. Thus the pump must
work at all timesalmost as though it were pumping straight into the
atmosphere, and any excess air produced and not used by appliances
must be bled away to the atmosphere (Figure 23). This makes for
pisto‘*… ……
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Bubble air-lter
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Mains supply
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Large chamber loosely packed
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With nylon wool
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Excess air to atmosphere <—
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Clamp/regulators
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Air to appliances
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Fig. 23. A' typical air-supply system with a piston air pump. The pump should
be mounted at least 12"_ above the water surface and should always be run at
high speed, any slowdown indicating a blockage or back-pressure build—up,
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'Which should 'be—dealt with either by clearance or by venting excess pressure
to
the atmosphere.lf the system incorporates an ozoniser, the water filter
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should be replaced with a silica gel column