Improvements in Safety Plugs for Steam Generators.
Year: 1888

page_text: TRUVIDIONAL
Improvements in Safety Plugs for Steam Generators.
I HENRY HILLER of Number 22 St. Anns Square, Manchester, in the County of
Lancaster, Chief Engineer of the National Boiler Insurance Company do hereby
declare the nature of this Invention to be as follows:-
My said Invention relates to the safety or fusible plugs which aro intended to
provide means for the escape of steam from steam Generators in the event of the
water level becoming lowered to a dangerous extent as is well understood and my
invention relates more particularly to the appliances usually termed double cone
fusible plugs and which consist in each case of a part or parts which is or are screwed
into or otherwise secured to a seating or mounting and provided with an inner
cone or blow out piece which is secured in a shell or cone by means of fusible metal.
As constructed previously to my invention the annular space between the base of the
blow out pieco and the circular wall of the cavity at the base of the blow out piece
or in the seating was comparatively small and as the smoke from the furnace has
had access to this cavity the deposit of hard carbonaceous matter in the said small
annular space has been sufficient in some cases to keep the blow out piece in position
after the melting of the fusible metal. To remedy this defect is the principal object
of my invention. In the cases wherein the screw plug is introduced from the
furnace or fire box I form the said plug with a collar which has not any part
projecting beyond or below the base of the blow out piece and I form the notches or
recesses with which the key is adapted to engage in this collar. By this construction
the area of the annular space between the base of the blow out piece and the wall of
the cavity in the seating is greatly increased so that there is less tendency for matter
to deposit and in case of such deposit matter will not have the same effect in sealing
or holding in position the blow out piece. The said collar upon the blow out piece is
coned or is suitably shaped to act as a valve when screwed home to its seating a
steam tight joint being thereby obtained. In the cases wherein the plug is intro-
duced from within the steam space of the generator I adapt the plug to be screwed

page_text: into the seating by means of an ordinary screw key or of a suitable key the plug
screwing home in a direction toward the interior of the furnace or fire-box. Tho
plug is formed with a turned conical or suitably shaped surface which fits a seating
as in the example first described. The cavity in the seating is by preferenco
larger in diameter than the screw plug so that there is a large clear annular spaco
between the base of the blow out piece and the wall of the cavity. I do not
however confine myself to the formation of the seating with such cavity. This
form of plug is more simple than the ordinary appliance and the part in which
the blow out piece is fixed can be readily fixed in the seating or be removed
therefrom.
Dated this 7th day of March 1000
DUTTON & FULTON,
1, St. James Square, Manchester,
Agents.

page_text: COMPLETE SPECIFICATION.
Improvements in Safety Plugs for Steam Generators.
I HENRY HILLER of Number 22 St. Anns Square, Manchester, in the County of
Lancaster, Chief Engineer of the National Boiler Insurance Company,, 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 and accompanying drawings:-
My said Invention relates to the safety or fusible plugs which are intended to
provide means for the escape of steam from steam Generators in the event of the
water level becoming lowered to a dangerous extent as is well understood and my
invention relates more particularly to the appliances usually termed double cone
fusible plugs and which consist in each case of a part or parts which is or are screwed
into or otherwise secured to a seating or mounting and is provided with an inner cone
or blow out piece which is secured in a shell or cone by means of fusible metal. As
constructed previously to my invention the annular space between the base of the
blow out piece and the circular wall of the cavity at the base of the blow out piece or
in the scating was comparatively small and as the smoke from the furnace has had
access to this cavity the deposit of hard carbonaceous matter in the said small annular
space has been sufficient in some cases to keep the blow out piece in position after the
melting of the fusible metal.
The objects of my Invention are to remedy this defect and to facilitato the
insertion and removal of the part containing the internal cone.
The manner in which I carry my invention into effect is illustrated in the
accompanying drawings to which I will refer when describing my invention
more fully.
In the said drawings Fig. 1 is an outside view and Fig. 2 a sectional view of
a safety plug constructed in accordance with my invention.
In this example the removable screw plug a is adapted to be introduced into
position or changed or replaced by operating from within the furnace fluc or fire
box without having to enter the boiler. Figs. 3 and 6 are sectional views of the
other class of safety plugs which are so constructed as to necessitate the entry of
the boiler when the screw plug is to be removed or re-placed. In Fig. 2 the
screw plug a is formed with a flange or collar a' which has a flat face a². This
collar does not project below the base of the blow out piece or otherwise the
said collar does not project beyond the said base in a direction toward the interior
of the furnace or firo box, when the safety plug is in position.
It will be seen that there is a considerable annular space between the base 6¹ and
the wall of the cavity in the seating c whereas in the safety plugs as previously
constructed the said base came very near to the said wall and was liable to be
cemented thereto by accumulated soot as aforesaid. In the example as illustrated
an ordinary accumulation of matter in the corner at d will not have the effect of
holding the blow out piece after the melting of the fusible metal. In Fig. 4 the

page_text: seating is lower and there is a slight modification in the form of the collar a'.
This Fig. and Fig. 5 illustrate the method whereby the screw plug is adapted to
be screwed into position the latter Fig. being a face view of the collar a¹ and of
the base of the said screw plug. Beveled notches e are cut in the said collar and
a key illustrated by Fig-7 is formed with projections which are shaped and
adapted to enter the said notches a central projection entering the cavity in the
screw plug. When the screw plug is placed upon this key the plug is securely held
in position and can be readily screwed into the seating. I consider the notches e as
shown to be more suitable than mere holes drilled in the collar as the notches will not
be so liable to be stopped up as such holes would be and a key will more readily
engage with the collar after the plug has been at work for some time but I do not
confine myself to the use of these notches. In Figs. 3 and 6 the screw plug is passed
downward into position instead of upward as in the other examples. When using
these terms upward and downward I am supposing the safety plugs to be in the
vertical positions represented. The plug a is adapted to be screwed into the seating
by means of an ordinary screw key the plug screwing home in a direction toward the
interior of the furnace or fire box. The screwed part being of moderate proportions
is more readily screwed into position or removed than the ordinary large cap formed
with an internal screw thread especially in cases wherein the seating has been in use
for some time and has become encrusted with deposit. The lower or inner end of the
screw plug is flush with the inner face of an inwardly projecting flange c¹ on the
seating when the plug is screwed fully home. If preferred the said lower or inner
end of the screw plug might project into the chamber in the seating. In all the
examples it will be seen that no part of the screw plug a extends below the base of
the blow out piece and that there is a comparatively large space between such base
and the wall of the cavity in the seating and that there is no corner below the said
base or close to the same to hold accumulated soot or matter. In all the examples
the comparatively large cavity in the seatings gives freer access of the heat to the
base of the blow out piece. The screw plugs in all the examples are coned or adapted
to make a tight joint with the seatings when screwed home.
C
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 1
claim is
(1) The safety plugs constructed as and for the purpose set forth and indicated.
(2) In safety plugs the formation and construction whereby a comparatively wide
clear space is left between the base and the wall of the cavity in eas and for the
purpose set forth and indicated.
(3) In the screw plugs of safety plugs the collar a¹ not extending below the base
formed with notches e substantially as and for the purpose set forth with reference to
Figs. 4 and 5 of the drawings.
(4) The combination of the screw plug a provided with the blow out piece band
screwed into a tapped hole in the crown of the seating e the parts being of the
formation substantially as set forth and indicated with reference to Figs. 3 and 6 of
the drawings.
Dated this 16th day of November 1888.
DUTTON & FULTON,
1, St. James Square, Manchester,
Agents.