Improvements in Conduit Tubes, more especially suitable for Electrical Conductors.
Year: 1896

page_text: Date of Application. 26th Oct.. 1896
Complete Specification Left, 9th Feb., 1897-Accepted, 27th Mar., 1897
Complete Specification Left, 9th Feb., 1897-Accepted, 27th Mar., 1897
[Communicated from abroad by EDWIN TRUMAN GREENFIELD, of No. 44 Broad
Street, New York City, in the County of New York and State of New York,
United States of America, Electrician.]
Improvements in Conduit Tubes, more especially suitable for
Electrical Conductors.
I, EDWARD HIBBERD JOHNSON, of Hotel Cecil, in the County of London, Electrician,
do hereby declare the nature of this invention to be as follows:-
.
This invention is directed particularly to armoured conduit tubes in which the tube
proper is composed of iron with a lining of insulating material, and its object is to so
construct such armoured conduit tubes that they will give the best possible insulating
effects to enclosed electrical conductors under all conditions of usage.
It has been found that in the practical use of iron armoured conduit tubes in which
paper treated with asphalt under heat is used as the insulating material, the insulating
lining will under certain conditions of temperature and moisture, become percolated
with moisture to such an extent as will greatly deteriorate its insulating qualities, and
it is with a view of overcoming this objectionable feature that the present invention
has been devised..
According to this invention the iron or analogous metal tube is provided with an
interior lining closely adhering to the inner wall thereof, the said interior lining being
preferably of oilcloth or any fibrous material which has been thoroughly subjected to
a bath of hot oil. To the inner wall of the first named lining is applied a second
interior lining which is preferably composed of
paper.
In the construction of this composite tube it is preferable to make the inner paper
tube by any of the well known methods now in general use, and then to form around,
or draw over this tube or core, a second tube of oilcloth with the painted surface
thereof on the outside; uniting the two tubes together by paste in any suitable and
well known manner. The armour tube is then heated to the desired temperature and
the compound tube composed of the paper and oilcloth tubes as described, is forced
therethrough.
The entire tube is then subjected to a bath of molten pitch or asphalt in such.
manner as to thoroughly impregnate the inner paper tube with the molten material.
This process of treatment is continued by successive dippings in a manner well known
by those acquainted with tube manufacture, until the pores of the inner tube are
sufficiently filled with the molten material and the iron or armour tube is covered with
a coating thereof. Under this process of treatment also, it will be noted that the
coating of paint upon the outer portion of the oilcloth tube will adhere to the inner
wall of the iron tube, thus causing the compound tube to firmly adhere or be secured
thereto.
It is not intended to limit the invention to the use of the commercial article of trade
known as "oilcloth" for the lining tube next to the inner wall of the armour tube, as,
for this lining, there may be used any fibrous material which has been treated with oil
or with an oily substance, as for instance, cotton, wool, or other cloth fabric, paper, or
in fact, any fibrous material which can be thoroughly saturated with an oil; or there
may be used in place of this oilcloth tube a lining of any fibrons material treated with,

page_text: rubber, either on one or both surfaces, or throughout its meshes or mass. The
invention is intended to include generically, the use of a lining tube between the walls
of the inner insulating tube and the iron armour, which lining tube shall be, under all
ordinary conditions of temperature and usage, impervious to moisture.
Dated this 26th day of October 1896
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.
Improvements in Conduit Tubes, more especially suitable for
Electrical Conductors.
I, EDWARD HIBBERD JOHNSON, formerly of Hotel Cecil, in the County of London,
but now of 527 West 34th Street, New York City, United States of America,
Electrician, 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 particularly to what are known as armoured conduit tubes in
which the tube proper is composed of iron with a lining of insulating material, and
its object is to so construct such armoured conduit tubes that they will give the best
possible insulating effects to enclosed electrical conductors under all conditions of
usage.
It has been found that in the practical use of armoured conduit tubes having an
interior lining of fibrous insulating material, the said insulating lining will, under
certain conditions of temperature and moisture, become saturated with moisture to
such an extent as to deteriorate its insulating qualities, and it is chiefly with a view
of overcoming this objectionable feature that the present invention has been devised.
According to this invention the iron or analogous metal tube is provided on its
interior surface with a lining or linings closely adhering to the inner wall thereof, the
said interior lining or linings being preferably of oilcloth or any fibrous material
which has been thoroughly subjected to a bath of hot oil or other appropriate substance
that will render it impervious to water.
I prefer to subject the tube thus formed to a bath of molten pitch or asphalt in such
manner as to thoroughly coat the inner lining and outer surface of the tube.
The invention will be fully understood by referring to the accompanying drawing,
in which,
Figure 1 is a longitudinal section of an armoured conduit tube embodying my
improvement; and
Figure 2 is a transverse sectional view thereof taken on the line 1, 1.
A is the protecting or armour tube, preferably of iron, and B B' the interior lining
closely adhering to the inner wall thereof. This interior lining is composed preferably
of two strips of oilcloth, or other fibrous material, which has been thoroughly subjected
to a bath of oil or any equivalent substance which renders it impervious to water.
I prefer to so line the tube A with the interior lining of one or more thicknesses,
as to produce the desired insulation. When more than one thickness is used I prefer
to have the linings break joints as shown at 6 b', Figure 2. After the tube A has thus
been provided with the interior lining closely adhering to its inner wall, I prefer to
subject it to a bath of molten pitch or asphalt in such manner as to thoroughly coat
the inner lining and the outer surface of the tube A.
This result is accomplished by successive dippings into the molten material in a
manner well understood by those acquainted with the manufacture of electrical
conduits.

page_text: I do not limit myself to the use of the commercial article of trade known as-
"oilcloth " for lining the inner wall of an armoured conduit tube, as I may use for
this lining any fibrous material which has been treated with oil or with any insulating
agent impervious to moisture, as for instance; cotton, wool, or other cloth fabric,
paper, or in fact any fibrous material which can be thoroughly saturated with a
moisture-resisting agent, such as linseed oil; or I may use in place of oilcloth a lining
of any flexible fibrous material treated with india-rubber either on one or both surfaces
or throughout its meshes or mass, my invention being designed to comprehend
generically the use of one or more linings in an armoured conduit tube, which shall
act as an insulating medium and which shall also, under ordinary conditions of
temperature and usage, be impervious to moisture and will readily yield or bend with
the armour without rupturing or otherwise impairing the integrity or imperviousness
of the moisture-resisting agent. This conduit may be bent while in a cold condition
without impairing its insulating and moisture-resisting qualities, which is a highly
useful and important feature in the work of installing the conduit. I do not limit
myself to the method of manufacture of the above described armoured conduit tube,.
as it is evident that this operation may be varied in several particulars and still result
in the production of a conduit having an external protecting armour and an internal
tube or lining of insulating material which is of a flexible nature and is impervious to
moisture in addition to its insulating qualities.
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 claim is :-
1. A conduit tube composed of metal armour and an interior lining of oilcloth or
the like with the painted surface thereof adhering to the inner wall of the armour,
substantially as described and for the purpose specified.
2. A conduit tube composed of metal armour and one or more interior linings of
fibrous material saturated or impregnated with a moisture-resisting agent, substantially
as described and for the purpose specified.
3. A conduit tube composed of metal armour and a lining or linings of fibrous
material impregnated with a moisture-resisting agent, said lining or linings and
moisture-resisting agent acting also as an insulating medium, substantially as-
described.
Dated this 9th day of February 1897
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.