Improvements in the Method of and Apparatus for Ventilating Manholes, Electric Light Boxes, and Underground Chambers or Cellars of all Sorts.
Year: 1895

page_text: Date of Application, 22nd Feb., 1895
Complete Specification Left, 23rd Dec., 1895-Accepted, 22nd Feb., 1896
PROVISIONAL SPECIFICATION.
Improvements in the Method of and Apparatus for Ventilating
Manholes, Electric Light Boxes, and Underground Chambers
or Cellars of all Sorts.
I, GEORGE HINDE NISBETT of "Ashfield," Huyton near Liverpool, in the
County of Lancaster, Electrical Engineer, do hereby declare the nature of this
invention to be as follows :-.
My invention relates to ventilating manholes, electric lighting boxes, and under-
ground chambers or cellars of all sorts, whereby a full circulation of air is
obtained and all accumulations of gas or vapour with liability to explosion is
avoided.
In carrying my invention into effect, the plan I prefer is to provide such
ventilation by suitable openings onto the footway communicating with the interior
of the box or chamber by means of channels, tubes or ducts, formed either in the
loose cover itself or in the surrounding stationary frame or box, or the frame and
cover may be so made that they shall form, when placed together, channels, tubes
or ducts. These tubes, channels or ducts may extend along one or more sides of
the box or they may extend across and communicate directly or indirectly
throughout a part or whole of its length with the surface of the footway or roadway
by means of a slot or series of holes in the crown of the channel.
The channel or duct is of such a size as to be contained where possible in the
depth of the frame or cover or both, and the depth of the frame or cover is so
arranged as to be as shallow as possible, in order that the surface water entering by
the openings on to the footway before mentioned may be drained from such channel
by a suitable pipe having as large a fall as possible and leading therefrom to the
roadway gutter.
In those cases in which this is not practicable, either because the cover is too
low, or is set in the carriage way, the surface water may be drained from the
channel by a suitable trapped pipe leading to the bottom of the box or chamber
which may have a sump there provided for it. From this sump it may be removed
periodically by any convenient means; or I may drain the water directly to the
sewer by a suitable pipe. The channel or tube before described communicates
with the interior of the box, pipe or chamber by means of a series of holes or a
slot or slots in the side of such channel, such holes or slots being arranged as high
up as is practicable to prevent the possible overflow of the water from the channel
to the interior of the box thereby. These holes or slots, I prefer to cover with a
fine mesh wire gauze, so arranged as to prevent the possibility of any foul gas that
may be present in the box, getting fired from the surface of the street, either by a
light thrown down or otherwise. I may also provide the channel or trough before
described with a series of holes or slots on the side or sides remote from the box in
such a way that they will communicate directly with the soil surrounding the box
and under the level of the surrounding pavement if any.
I take precautions when excavating for the building or placing of a box at a
particular point to make such excavation of a larger size than the box to be placed
therein, then when the box (which may be of brickwork, iron or other suitable
material) is in place I fill in round it, with some porous material, such as coke
breeze, sand, hollow bricks or other material. Any gas or other vapour finding

page_text: its way to the neighbourhood of the box will naturally percolate through such
porous material, and find its way to the surface of the street through the holes or
slots in the sides and top of the channel as described and so out.
suitable guard over these holes in the outside of the channel to prevent the
I provide a
accidental filling of them with hard earth or other material. These holes so
described, on the outside of the channel may serve also to drain away the surface
water finding its way into such channel through the openings in the surface of the
box or street, and may be used alone for this purpose, or in conjunction with the
drainage pipe as described. In those cases in which a more rapid circulation of
air is desired than is provided by the one or more openings on the surface of the
footway as described, I so arrange the box and cover that part of the channel
described is isolated from the rest of the channel and is connected with a pipe
which leads to the bottom of the box. In this way I obtain a difference in levels,
the fresh air coming to the bottom of the box through the pipe and the gas laden
and therefore lighter air going out directly through the other portion of the
channel to the surface of the street.
I prefer to make the openings on to footway before described in the form of
slots, as it is then easy to clear the channel from mud and dirt by passing a suitable
scraper or brush down from above and forcing it from end to end. The surface of
the cover may he of cast iron or it may have a stone or other slab of suitable material
fitted into it.
Dated this 21st day of February 1895.
WM. P. THOMPSON & Co.,
Of 6 Lord Street, Liverpool, Patent Agents for the Applicant.
Improvements in the Method of and Apparatus for Ventilating
Manholes, Electric Light Boxes, and Underground Chambers
or Cellars of all Sorts.
I, GEORGE HINDE NISBETT, of "Ashfield," Huyton, near Liverpool, in the
County of Lancaster, Electrical Engineer, 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 :-
This invention relates to ventilating manholes, electric light boxes, and under-
ground chambers or cellars of all sorts, whereby a full circulation of air is
obtained and all accumulations of gas or vapour with their liability to explosion are
avoided.
The accompanying drawing sets forth one form of my apparatus. In this,
Figure 1 is in part a front elevation and in part a cross section of my improved
ventilating manhole;
Figure 2 is a plan of the entire maubole on a reduced scale ;
Figure 3 a detail view of a corner of the cover.
In these,
A is a brickwork, iron or other chamber, B a cover frame therefor, B' an outer
frame, which may or may not be cast in one with the frame B. It will be found
cheapest, however; to cast the two frames separately but with a rib at intervals at f
attached to one or other of the frames. Between these two frames B B' is a duct or
channel D. This duct or channel D can go partially or wholly round the chamber.
In most cases it is sufficient to have it only on two sides. C is a cast iron cover
plate having preferably a shallow recess in the top as shown, which is filled with a
block of stone cement of any kind roughened so as to, prevent slipping, or this
cover plate can be level with its edge but fluted so as to prevent persons slipping
募
.
10.

page_text: on it.
Between the cover C and outer frame B¹, I leave a hiatus or slot E,
bridged over at intervals, however, by projections from either the frame B' or
preferably the cover C, or there may be simply one or more holes at intervals >
round the chamber. The edge of the cover alongside this hole projects as set
forth at H so as to prevent the water by capillary attraction running along the
cover to the interior of the chamber. A series of holes G is placed in the cover.
connecting the interior of the chamber A with the channel D, and attached to the
cover C in any suitable manner I place a sheet of fine metallic gauze or finely.
perforated metal g so that there shall be no connection between the openings G.and
the chamber A, except through this wire gauze, which must be of that degree of
fineness sufficient to prevent the passage of flame, in fact of about the same degree,
of fineness as is used in Davy's safety lamps and the like.
The mode of action is as follows:-
Any water in the roadway running down into chamber D is carried off through
the ducts which can lead direct to a drain through a trap or into a bed of.
porous material such as coke, brickbats, sand and the like below the roadway or
surrounding the chamber, the walls of which in such a case are preferably laid in
cement and made of blue or other waterproof bricks. Any gas formed in the
chamber A rises through the gauze g and out through the holes G into the duct D,
and from thence escapes through E.
In order to enable this to be done more effectually, I may in some cases connect
chamber A with a syphon or air stand-pipe having a protected top so as to admit,
of a circulation of air through passage E, D, G and g to A, and thence up the
stand pipe or in the reverse direction. By this means a constant current is kept
up without the liability of water entering, and thus all chance of accumulation of
gas is avoided.
In most cases however I prefer to form one part of the channel D separate from the
rest, and connected by water-shielded openings either with the upper part of the other
part of the chamber D or with the open air, and in this isolated portion of channel D
place a syphon instead of the stand pipe connected with the bottom of chamber A.
The air can then keep up a circulation as follows-From the open air to the
isolated portion of channel D, thence through the syphon pipe to the bottom of
chamber A, thence through parts g G, D, E, or vice versa.
The channel or duct D is of such a size as to be contained where possible in the
depth of the frame. It may however be arranged in the cover itself, which may
dip down over a curb b and itself form a channel, otherwise both the frame B and
the cover C are preferably made as shallow as possible.
The slots G should also be made as high up as practicable so as to leave less
chance for the water to be able to rise to them in channel D.
The frame B' can be provided if desirable with numerous holes communicating
with the adjacent soil, and the parts adjacent to it can as before mentioned be filled
with coke breeze, sand, hollow bricks, brickbats, gravel or other material capable
of holding a considerable supply of water while maintaining the surface.
Gas percolating from pipes below the street finding its way to this porous or
cellular material escapes through the holes in part B₁ to the surface of the street
by means of slots F and E, and in such case the holes in frame B₁ may be
provided with guards as shown or other means to prevent them being easily choked
with earth and in this way the soil surrounding the box is ventilated and thus a
head of gas against the box and consequent tendency to enter is avoided. My
object in forming the openings E as slots instead of round holes is that they may
be more easily cleared of mud and dirt by means of a scraper or brush.
The outer rim may be serrated, crenulated or formed as shown at C with ribs so
as to prevent it being slippery in wet weather.
From the foregoing it will be seen that my device is complete in itself. It can be
used where there are no drains as the porous matter round it acts as a drain, it
will also ventilate itself without being connected with a chimney shaft, a pipe up
the wall of a neighbouring house, or the like.

page_text: :
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The improvement in ventilating manholes and the like, which consists in
forming the frame with two walls with a channel (D) between, having a duct (F)
leading to the drainage, a slot or duct (E) leading to the. surface, and a slot or
duct (G) shielded by a lip (H) or otherwise from the admission of water connecting
the channel (D) near its top with the interior of the manhole, substantially as
.described.
2. In combination with a manbole, electric light box or underground cellar or
chamber having a cover and frame substantially of the type or character described,
a space surrounding or partially surrounding the same filled with porous materials
having air spaces in its texture whereby the soil surrounding the manhole box or
chamber is ventilated and also the porous material acts as drainage for the structure,
substantially as described.
3. In combination with a manhole, electric light box, or underground chamber
or cellar cover, a passage for air into the upper part of an exterior chamber or
channel open to the air, said passage being protected from the entrance of water
from the exterior chamber by a dependent lip or equivalent means and separated
from the main chamber by a large expanse of finely perforated uninflammable
material, whereby even if an explosive mixture of air and gas escape from the
-chamber and be accidentally lighted, the flame is intercepted from the chamber.
4. The method of ventilating manholes, electric light boxes and underground
chambers or cellars, which consists in connecting said manhole or other chamber
at its upper part with a second smaller chamber or channel, and its lower part
with a third chamber or channel, both of these two smaller chambers or channels
being open to the atmosphere, and the connections being shielded from the entrance
-of water.
5. The apparatus for ventilating manholes, electric light boxes and underground
chambers or cellars, constructed and arranged substantially as described and
:illustrated.
D
ה.
21
1
1005
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Birmingham, and London, Patent Agents.