The Hawaiian gazette., 1873-05-21

possible, and we are continually replacihS
zone piece Of machinery with another, if
the slightest improvement is manifest
This Is especially the case with pumps, of
which there are probably more varieties
and notifications than in any other class
Of machinery, with the exception, per-
hzps, Of washing machines In each of
these inventions we try to simplify as
much rs possible the complications of
previous articles. With simplicity of
construction we attain not only that de-
sirzble object, cheapness, but gain space,
reduce friction, and lessen the liability of
the machine getting out of order. One
Of the late inventions in the line of steam
pumps, which shows a wonderful sim
pIicity Of construction and operation, is
called the Prall Automatic Steam-Con-
densing, Vacuum and Force Pump We
recently saw this pump in operation
81 the Pacific Iron Works on First street,
IN this city CSan Francisco,) where it can
be seen by those interested
The cylinders are made of metal, lined
with wood. Into the upper end of these
cylinders a small steam-pipe is led from
the boilers, the pipe being opened and
closed by simple two-way valve. A
fat plate is placed opposite the mouth of
the steam-pipe in the top of the cylinders
odehect and difuse the steam as it enters.
To the bottom of the cylinders is con-
nected a single suction-pipe- Simple
checkvalves are placed on both the sue
ton and discharge-pipes to prevent a
refow of the water passing upward. The
valve-chambers are constructed with face
plates, which admit of ready detachment,
so as to admit of removing and replacing
the valves. a small injection-pipe COM
municates from one cylinder to the other,
through the valve-chest, and throws jet
OF water into the steam as soon as soon
as Il has driven the water out of the cyl
Under A vacuum Is thus formed, which
draws the water from the suction-pipe
and again fills the cylinder.
The automatic movement of the steam
valve, which admits and shuts off steam
al the proper moment, is produced by
means Of diaphragm of rubber, or of
thin elastic metal, and connected with the
valve by a simple rod This diaphragm
Is placed between two disks, which are
slightly dished on their inner sides to ad-
NIT of a play or movement of the centre
Of the diaphragm between them, equal to
the extent of movement required in the
valve. This diaphragm is connected to
the cylinders by water channels moved
by alternate pressure on each side, thus
admitting steam to one cylinder by down
ward movement, and to the other by
upward. An air-valve is placed in the
upper part of each cylinder, admitting
little air into the top of the cylinder
whenever a vacuum is formed.
In the operation of pumps thus con-
structed the pressure of the water in the
cylinder when filed. bearing against the
diaphragm, will bear it up against its
upper plate. The movement communi-
Gated through the rod to the upper valve
Is sufficient to open the valve wide. If
steam be now admitted through the steam
pipe, It viii pass through the valve at the
upper end, and entering the cylinder will
be diffused by the plate placed under the
opening, into stratum of air upon the
water. The stratum of air serves to pre-
vent al agitation of the water by the
steam when it enters, so that it will spread
itself quietly and evenly over the entire
surface, and operate directly and as eff
fectively as if upon the piston of an ordi-
nary steam-pump. The very thin film of
air being instantly heated at the first con-
tact Of the steam, all further condensation
Of the latter is entirely prevented, and the
full pressure of the steam is brought to
bear upon the water, to force it out of the
pump through the dischsrge-pipe, noise
lessly, and without friction, to any de-
sired height, in proportion to its initial
pressure When, however, the steam, in
expelling the water from the cylinder,
follows it into the discharge-pipe, it is
partially condensed, and the pressure on
the under side of the diaphragm is so far
removed SIS to cause the latter to move
and close the steam-Yalye, whilst sufficient
water is simultaneously withdrawn from
the injection-pipe to complete the entire
condensation of the steam, and produce
vacuum which will cause the cylinder to
promptly fill from the suction-pipe As
soon as the cylinder is filed, the dia-
phragm viii again move under the pres
sure thereon, steam viii again be admit
ted, and the operation of the pump thus
repeated. One cylinder is being filed
while the other is being emptied, so the
fow is continuous, and no intermittent
action Is apparent
In one of the simplest adaptations of
the pump for operating with steam at