Year: 1898

page_text: Date of Application, 25th Jan., 1898-Accepted, 2nd Apr., 1898
I, MARCO SACCARDO, Royal Inspector and Railway Engineer, of Bologna, in the
Kingdom of Italy, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement :—
My invention relates to an improved method and apparatus for the artificial ventila-
tion of railway tunnels and the like.
Almost all railway tunnels possess to a more or less degree the drawback that the
air vitiated by the smoke of the locomotive is rendered unsuitable for respiration, and
may injuriously affect the health of the officials. Many improvements have been
tried for removing this drawback, some of them of a transitory character, such as
for instance means of safety which, inserted in the tunnels at intervals, are
intended to protect the officials against the danger of asphyxia; others of a more
permanent character devised to produce a strong current of air for the purpose of
driving out the vitiated air, and replacing it by pure air. These improvements
are usually divisible into two kinds, either artificial ventilation or natural ventila-
tion. When the position of the tunnel admits, it is usual to construct ventilating
shafts, even at considerable outlay, but where this is impossible it is necessary to
have recourse to artificial ventilation. Apart from the fact that even the natural
ventilation has frequently only a passing effect and causes much disappointment,
it must be noted that artificial ventilation is not at all easy to apply. The use
of a centrifugal apparatus or fan at the entrance of the tunnel has been proposed
for the purpose either of injecting pure air or drawing out the spoilt air, but this
arrangement would require the application of a door at the entrance, which would
be very dangerous, and almost always incompatible with the requirements of the
service of the railway. It has also been suggested to draw out the vitiated air from
the tunnel by means of special conduits in communication with the centrifugal
apparatus and having their orifices in the interior of the tunnel at one or more points.
Nevertheless this arrangement invariably requires an immense outlay without the
certainty of obtaining the desired result. But ventilation itself is a thing which if
properly directed should in general succeed, but the principal defect lies just in the
fact that hitherto no importance has been attached to the direction of the ventila-
tion. This consideration is of great importance, for if the ventilation takes place in
the same direction in which the train passes, and with a velocity equal, or almost
equal, to that of the smoke with regard to the movement of the train it will be
either neutralized or very small, and the smoke will remain still more and more strong
around the train. Ventilation in this case has simply rendered the hygienic condition
of the tunnel worse instead of making it better.
All the above mentioned drawbacks may be remedied by means of my invention,
which consists essentially of a ventilating apparatus applied to one of the entrances
of the tunnel, and arranged so as to cause in the same a strong air current by means
of the special apparatus, (and without having recourse to any closing device) in the
direction contrary to that of the train on the rising grade, or if the tunnel is of
Do1

page_text: double incline, the up-draught can be applied in the direction contrary to the longest
slope or that of the greatest inclination.
Experiment has proved that this arrangement has always given favourable results.
The invention is illustrated diagrammatically in the accompanying drawing, in
which
Figure 1 represents a horizontal section of the apparatus placed at the highest
entrance to the tunnel.
Figure 2 represents the same apparatus placed at the lowest entrance to the
tunnel.
In Figure 1 E represents an annular chamber which surrounds the whole or a great
part of the circumference of the gallery a b, and which chamber is in communication
with the ventilating apparatus T by means of the conduit E', the internal section of
which increases gradually from the ventilating apparatus to the annular chamber.
To the said annular chamber is applied the converging tube C also of annular section.
The air compressed in the chamber E escapes from the annular tube C, forming a con-
tinuous jet of air. Its force produces between the front part and the hind part a
difference of pressure which will induce a current of air to pass through from one end
to the other of the tunnel a b in the direction indicated on the drawing by the arrow.
The outer part f g of the tube may be graded to fit the outline of the interior part
of the tunnel which at this point can take a shape different from that of the normal
section of the tunnel. This device is indicated in Figure 1 by the letters g h i.
My apparatus may be applied in the opposite direction as shewn in Figure 2. In
this case it is advisable to add to the apparatus a diffusion tube indicated in Figure 2
by the letters ghi. The air set in motion by the apparatus T can then be taken,
either from the exterior or the interior of the tunnel by means of the conduit shewn
dotted 8, Figure 2. The apparatus will act not only at one or the other of the
entrances of the tunnel, but also in the same manner if it be placed at a point within
the tunnel. If the tunnel which is to be ventilated is of large dimensions a number
of apparatuses may be used arranged in series or otherwise. The annular converging
tube C instead of passing all round the tunnel may be suppressed in parts, as for
instance at the point where the rails pass or at other points as may be considered
desirable. The walls of the apparatus and of its accessories may be constructed of
wood, metal, masonry, or may be of composite construction.
Taking into consideration the enormous expense to which railway companies are
subjected in order to improve the ventilation of their tunnels, and the unsatisfactory
results hitherto obtained it will easily be seen how advantageous my invention will
be, as it produces a favourable ventilation in any desired direction and causes an
expense relatively small, both for its construction, and for its maintenance.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what I 4
claim is :-
1. Improved apparatus for the artificial ventilation of tunnels consisting essentially
of an annular chamber with additional convergent pipe of annular section, the said
chamber receiving air from a fan or the like, and passing the same into or out of the
tunnel causing a very strong current of air in a direction contrary to that of a train 4
proceeding on the up grade of the said tunnel, substantially as described.
2. The improved apparatus for ventilating tunnels, constructed and operating sub-
stantially as described with reference to the accompanying drawing.
Dated this 25th day of January 1898.
Dated this 25th day of January 1898.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.