‘
-
[‘
AîrSupplie’s"
‘
'
_
_j ;
,59' 5 ' …
Itis well ‘khOWn that
(average valueï'l4‘ÿ7
pounds per
Will support a water column 34 ft high…
…
From this fact it can be calculated that
only one inch high
is supported by a pressure of only 0.0036 pounds per square inch. ‘
»
Therefore, to force air to a depth of even 24 in., which is deeper than
_
aquaa,- only a very small pressure is‘required. This
'
'
conclusion is of great importance to aqùarists for it allows the uSe '
»
of extremely simple air pumps.
The most popular type of small pump uses the vibrating diaphragîm ,
'
mechanism which pushes air through a simple automatic valve system,
and is operated by a magnetic coil fed directly from the mains supply
(Figure 20). These pumps are cheap, efficient, easy to repair and
Movement
.
'
.
Coil termiñäls
,
% I Dîaphrâgm
Enerngan
W/
Arm
\
Magnet\
Ç0”
.
Diaphragm
"
,
Pivot
\ |
_
Iê SUPP'V
Chamber
/
\
chamber
.
Ê/
Input chamber
Output chamber
Diaphragm
'
Air out
’
…
"
,
"
(a)
=
'
arm
_
Fivot
'
.
—Î
Diaphragm
————_'—'__——
.
?
-
‘
_
-
L
'
_
coil"
«
Ôî_r°Ut .
'
Mains supply
'
—
-
°
'
-
Coil terminals ' '
Base
'
,_
.'
2
:
F1g
:‘(a)Mhdéfir,
I_j
!
;.
Chamber—f
'
_
—;«.‘
‘
_
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