IMPROVEMENTS IN DETECTING AND PREVENTING CORROSION IN STEAM BOILERS AND PARTS CONNECTED THEREWITH, AND IN APPARATUS THEREFOR."
Year: 1880

page_text: LETTERS PATENT to George Weir and James Weir, both of Glasgow, in
the County of Lanark, North Britain, Engineers, for an Invention of
"IMPROVEMENTS IN DETECTING AND PREVENTING CORROSION IN STEAM
BOILERS AND PARTS CONNECTED THEREWITH, AND IN APPARATUS THEREFOR."
PROVISIONAL SPECIFICATION left by the said George Weir & James Weir
at the Office of the Commissioners of Patents on the 27th October 1880.
GEORGE WEIR and JAMES WEIR, both of Glasgow, in the County of Lanark,
North Britain, Engineers. "IMPROVEMENTS IN DETECTING AND PREVENTING
CORROSION IN STEAM BOILERS AND PARTS CONNECTED THEREWITH, AND IN
APPARATUS THEREFOR."
This Invention has principally for its object to prevent or diminish corrosion in
steam boilers and parts connected therewith, and also comprises means and
apparatus for detecting corrosive tendency or ascertaining its absence in the
water supplied to steam boilers.
The present Invention comprises improvements based on the views and principles
described in a Provisional Specification lodged by the present applicants on the
25th June last (No. 2590). The corrosive tendency of the water supplied to steam
boilers may be neutralised by preventing the absorption of corrosive gases in the
water, or by removing such gases from the water, or by combining an anti-corrosive
gas or gases with the water, such anti-corrosive gas or gases either preventing the
absorption of injurious gases, or rendering them innocuous when present; or by
combining the use of an anti-corrosive gas or gases with that of means or apparatus
for removing or preventing the absorption of corrosive gases.
In many existing arrangements of marine and other steam engines, the feed
pumps are proportioned to have an action somewhat in excess of what is
absolutely necessary, and they consequently often draw in air along with the
water, being worked always at a speed the same as or corresponding to that of
the main engines. By the present Invention a separate small engine is arranged

page_text: for working the feed pumps, and a cistern is provided from which the pumps draw
the water, and which has in it a float, or piston, or diaphragm connected to the
valve, supplying steam to the small engine in such a way that the steam is shut
off when the cistern becomes nearly emptied, and is more and more opened the
fuller the cistern is. The pumps will in consequence be worked just in proportion
to the supply of water, and will not draw in air when there is little or no water to
These pumps
pump.
will by preference be of such a size that their maximum
speed will be moderate, so that they may not be subjected to severe concussive
strains caused by pumping an inelastic liquid at a high velocity. Or the pumps
may be worked by the main engines, but having their discharge pipe or pipes
connected to the cistern through a by-pass valve acted on by the float, piston, or
diaphragm in the cistern, so that when the water level in the cistern becomes
lowered some of the water pumped will return to the cistern, and thus prevent the
pumps from drawing air. Or again, the float, piston, or diaphragm in the cistern
may be arranged to act on mechanism for varying the length of stroke of the
pumps, whereby the same result will be attained. The ordinary donkey engine
and pumps used for supplying water to the boilers when the main engines are not
working, will by preference have the delivery pipes arranged so that the water from
them passes into the cistern connected to the separate pumping engine herein before
described, and when a feed heater with air separating apparatus is fitted in
connection with the engines, the water will be delivered into such heater, and will
find its way thence in the ordinary way to the cistern.
In cases in which water supplied for the boilers contains or is liable to contain
air or injurious gas, it may with advantage be led into the condenser by preference
at the hottest part, or into any other suitable vessel in which a diminished pressure
is maintained, being withdrawn from such condenser or vessel in such manner as
not to reabsorb the air or gas, which separates from it through the influence of the
diminished pressure.
For the purpose of ascertaining the condition as regards corrosive tendency of
water that is being fed into a steam boiler, apparatus is by this Invention provided
for rendering the action of the water visible without interfering with the working
of the boiler or of the engines, or of any parts connected therewith; and one
modification of this apparatus is arranged to admit of samples being taken away
from any part in such a manner as to avoid any change of condition which might
be considered likely to modify the results shown by the sample. A glass tube is
provided for holding the sample, and is fitted with metal end pieces connected by
an iron rod, upon which they are screwed water-tight when filled with the sample
of water. When a sample is to be taken the sample tube is placed in a close vessel
provided with two connecting pipes, having stop valves for attachment to the feed
pipo or other part from which the sample is to be taken. The cover of the vessel
which is removed for the introduction of the sample tube is made with a stuffing
box through which a key rod is passed; and when the vessel is closed with the
sample tube inside, the key rod engages with one end piece of the tube, whilst
the other end piece engages with a socket provided for the purpose in the vessel.
The water having been made to flow through the vessel sufficiently long to insure
the complete filling of the sample tube, the key rod is turned to screw the end
pieces hard up; and then after the stopcocks of the connecting pipes have been
closed, the vessel is opened, and the sample tube is removed. If there is any
corrosive tendency in the water in the sample tube, it will show itself in a very
short time by corroding the iron rod; and if desired, the tube may be kept heated,
so that the water may be in the same condition as in the boiler. The sample tube
may be fitted with a pipe instead of a rod, to admit of its being conveniently
heated by directing a jet of steam into such pipe. A sampling vessel, such as has
been described, may be connected to the boiler, or to the feed pipe between the
boiler and an air separator when one is applied externally, or between the air
separator and the feed pumps, or between the feed pumps and the hot well (or feed
heater when one is used), or between the condenser and the air pump, or to any

page_text: other part; or two or more such sampling vessels or other modifications of the
corrosion detector may be connected to different parts for the purpose of comparison.
In illustration of the uses of the corrosion detectors, it may be stated that in
experiments made with them, it has been found that water taken immediately from
the condenser of an ordinary surface-condensing marine engine shows little or no
corrosive tendency; whereas, when taken after passing the air pump, it shows
considerable corrosive tendency, and still more after it has passed the feed pumps,
thus corroborating the opinion that it is air absorbed during the passage from the
condenser to the boiler which imparts a corrosive tendency to the water.
Instead of the corrosion detector apparatus with removable sample tubes,
permanent glass detector tubes may be fitted to the various parts thought desirable,
each tube having at each end a stopcock connection with the pipe or other part
containing the water to be examined, and having passing through it an iron rod, or
by preference an iron pipe on which any corrosive action may show itself, such rod
or pipe being made removable for the purpose of being cleaned.
By the present Invention it is proposed to employ zinc in a systematic and
economical manner for obtaining hydrogen to act as an anti-corrosive in the water
of steam boilers, the applicants having ascertained that zinc will yield hydrogen
when placed in heated water (even in a glass vessel). A separate vessel connected
with the boiler or feed pipe or other suitable part may be provided for subjecting
the zine to the action of heated water or steam, such vessel being fitted with a cover
and with stopcock connections, by means of which the supply of hydrogen may be
regulated to suit the requirements; or the zinc may be introduced into the boiler,
but in the latter case, instead of placing it therein in large quantities in the
wasteful manner hitherto done with the expectation of its affording protection
through galvanic action, it is to be supplied through special apparatus in small
quantities at frequent intervals as it may be required. One mode of introducing it
is by passing it in the form of a rod through a stuffing box; or it may be introduced
in small pieces or in a granular form through a pipe or passage fitted with two
valves, the zine being entered through the outer valve whilst the inner one is
closed, and afterwards allowed to pass down through the inner one whilst the outer
one is closed.
In withdrawing water from the bottom of a surface condenser by a passage
leading to a feed pump, and separate from that leading to the air pump, as described
in the Provisional Specification hereinbefore referred to, it is sometines inconvenient
to place the foed pump so low relatively to the bottom of the condenser, that the
water will have head enough for easily opening the foot valves. To overcome this
difficulty a steam jet is by the present Invention introduced into the pipe between
the condenser and the feed pump, and gives to the water sufficient force for opening
the foot valves, even if the pump is placed at a level above that of the bottom
of the condenser; or the water may be raised in any convenient way so as to
acquire the necessary head. When feed-heating apparatus is fitted close to the
condenser, or even inside of it, such apparatus may be modified or be supplemented
with parts to separate air from the water, such air-separating parts being substan-
tially such as are referred to in the Provisional Specification herein before referred
to, the object being in all cases to avoid the absorption of air by the water which is
fed into the boilers.
In some cases feed injectors may be substituted for the feed pumps hereinbefore

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Weir & James Weir in the Great Seal Patent Office on the
26th April 1881.
GEORGE WEIR and JAMES WEIR, both of Glasgow, in the County of Lanark,
North Britain, Engineers. "IMPROVEMENTS IN DETECTING AND PREVENTING
CORROSION IN STEAM BOILERS AND PARTS CONNECTED THEREWITH, AND IN
APPARATUS THEREFOR."
Our said Invention has principally for its object to prevent or diminish corrosion
in steam boilers and parts connected therewith, and also comprises means and
apparatus for detecting corrosive tendency or ascertaining its absence in the water
supplied to steam boilers.
Our present Invention comprises improvements based on the views and principles
described in the Specification of Letters Patent granted to us, and dated 25 June
1880 (No. 2590). The corrosive tendency of the water supplied to steam boilers
may be neutralised by preventing the absorption of corrosive gases in the water,
or by removing such gases from the water, or by combining an anti-corrosive gas
or gases with the water, such anti-corrosive gas or gases either preventing the
absorption of injurious gases or rendering them innocuous when present; or by
combining the use of an anti-corrosive gas or gases with that of means or apparatus
for removing or preventing the absorption of corrosive gases.
In many existing arrangements of marine and other steam engines the feed
pumps are proportioned to have an action somewhat in excess of what is absolutely
necessary, and they consequently often draw in air along with the water, being
worked always at a speed the same as or corresponding to that of the main engines.
By our present Invention a separate small engine is arranged for working the feed
pumps, and a cistern is provided from which the pumps draw the water, and which
has in it a float, or piston, or diaphragm connected to the valve, supplying steam
to the small engine in such a way that the steam is shut off when the cistern
becomes nearly emptied, and is more and more opened the fuller the cistern is.
The pumps will in consequence be worked just in proportion to the supply of
water, and will not draw in air when there is little or no water to pump. These
pumps will by preference be of such a size that their maximum speed will be
moderate, so that they may not be subjected to severe concussive strains caused by
pumping an inelastic liquid at a high velocity.
And in order that the improvement herein before partly described and others
comprised in our present Invention may be properly understood, we hereunto
append five Sheets of explanatory Drawings to be hereinafter referred to, and
bearing reference numerals, the same numerals being used to mark the same or like
parts wherever they are repeated.
Figure 1 on Sheet 1 of the accompanying Drawings is a sectional elevation of
one modification of our improved apparatus as constructed to avoid the drawing
in of air along with the water by the pumps used for feeding a steam boiler. The
feed pump 21 in this example forms part of a direct-acting steam pump, being
combined with and worked by a steam cylinder 22, the steam for which is supplied
by a pipe 23, having on it a valve or cock 24 controlled so as to shut off the steam
when the supply of water for the pump is too much reduced. The lever of the
cock 24 is connected by an adjustable rod 25 to a lever 26 on a spindle 27, which
passes through a stuffing box into a small cistern or casing 28, and therein has fast
on it a pair of levers to which there is attached a float 29. From the casing 28
the water passes by a pipe 30 to the feed pump 21, whilst the casing may receive
the water from any convenient source; it is however shown as arranged to receive

page_text: it from a simple kind of feed heating apparatus placed inside of a surface con-
denser 31. The feed heating apparatus, shown in Figure 1, consists of a perforated
cylinder 32 placed in the passage 33, by which the exhaust steam from the main
engines enters the condenser. Inside of the perforated cylinder 32 there are a
number of disks 34 strung on a vertical rod, and kept at suitable distances apart
by short tubes strung on between them, these disks serving to scatter the feed
water which enters by a nozzle 35 above. The feed water descending through
the perforated cylinder 32 takes up heat from the steam entering the condenser,
and is caught by a duct 36 which leads it to the cistern or casing 28. The
nozzle 35 by which the water enters the feed heating apparatus is the upper end
of a pipe 37, which proceeds from a small cistern or casing 38 into which the water
of condensation from the condenser 31 is delivered by the air pump or by a
separate pump. This cistern 38 is fitted with a valve 39 connected to a float 40,
arranged so that the valve closes when there is not enough water in the cistern to
quite cover the outlet, by which means air is prevented from passing by the pipe 37
into the condenser 31.
Figures 2 and 3 are enlarged horizontal and vertical sections of a cistern or
casing 28 and Hoat 29 acting like those shown in Figure 1, but modified for
receiving the feed water through a check valve 41 directly from a pump or from
feed heating apparatus not arranged in the condenser like that shown in Figure 1.
A handwheel and screw spindle 42 is shown fitted in connection with the check
valve 41 to permit that valve to be used as a check valve. A pipe 43 with a stop
cock is shown fitted to the top of the cistern 28 for leading off air or gas to a
condenser or other part.
In other modifications the feed pump is worked by the main engines, and in one
of these modifications, shown in vertical section in Figure 4 (Sheet 3), the discharge
pipe 44 is connected to the cistern 28 by a branch pipe 45 and a by-pass valve 46,
acted on by the float 29, or it might be by a piston or diaphragm in the cistern, so
that when the water level in the cistern becomes lowered some of the water
pumped will return to the cistern and prevent the pump from drawing air. Or
instead of the by-pass valve 46 being in the cistern, and external lever on the float
lever spindle 27 may be connected by a rod 47 to a by-pass cock or valve 48 fitted
in a passage formed in the valve box of the pump, so as when open to allow the
water pumped to return into the suction or inlet pipe 30. Or again, the float,
piston, or diaphragm in the cistern 28 may be arranged to act on mechanism for
varying the length of stroke of the pump or pumps whereby the same result will be
attained. An arrangement of this kind is shown in vertical section in Figure 5,
and in it the feed pump 21 is worked by a rotating crank 49, driven from the main
engines at a speed which is reduced by gearing 50. The connecting rod 51 from
the crank 49 is jointed to a small cylinder 52, guided so as to be movable in the
line of the pump rod 53, which rod has a piston 54 on its upper end working in
the cylinder 52. Passages between the ends of the moving cylinder are controlled
by a hollow plug valve 55, made with a square spindle 56, which works freely
through the square eye of a lever 57 carried by a bracket 58, the lever being con-
nected to the external lever on the float lever spindle (27) of the cistern (28). When
there is plenty of water in the cistern (28) the valve 55 is closed and the water
locked in the two ends of the movable cylinder 52, so that the pump rod 53 is
worked as though directly jointed to the connecting rod 51; but when the water
in the cistern (28) becomes too low, the float (29) causes the valve 55 to be opened
and then the cylinder 52 moves up and down without moving the pump rod 53 to
the extent of its maximum stroke, because of the water being able to get from one
end to the other of the movable cylinder 52. Any other suitable mechanism for
varying the stroke of the pump rod 53 may be employed; thus, for example, the
pump rod 53 may be jointed to a curved slotted lever, indicated by dotted lines
at 59, the connection with the rod 51 being movable along the slot through the
action of the float (29) in the cistern (28). The ordinary donkey engine and pumps

page_text: used for supplying water to the boilers when the main engines are not working
will by preference have the delivery pipes arranged so that the water from them
passes into the cistern connected to the separate pumping engine hereinbefore
described; and when a feed heater with air-separating apparatus is fitted in con-
nection with the engines the water will be delivered into such heater and will find
its way thence in the ordinary way to the cistern.
In cases in which water supplied for the boilers contains, or is liable to contain,
air or injurious gas, it may with advantage be led into the condenser by preference
at the hottest part, or into any other suitable vessel in which a diminished pressure
is maintained, being withdrawn from such condenser or vessel in such manner as
not to reabsorb the air or gas which separates from it through the influence of the
diminished pressure.
For the purpose of ascertaining the condition as regards corrosive tendency of
water that is being fed into a steam boiler, apparatus is by this Invention provided
for rendering the action of the water visible without interfering with the working
of the boiler or of the engines or of any parts connected therewith; and one modifi-
cation of this apparatus is arranged to admit of samples being taken away from
any part in such a manner as to avoid any change of condition which might be
considered likely to modify the results shown by the sample. In this modification,
which is shown in vertical section in Figure 6 (Sheet 4), a glass tube 60 is provided
for holding the sample, and is fitted with metal end pieces 61 connected by an iron
rod 62, upon which they are screwed water-tight when filled with the sample of
water. When a sample is to be taken the sample tube 60 is placed in a close
vessel 63 provided with two connecting pipes 64, 65, having stop valves for attach-
ment to the feed pipe or other part from which the sample is to be taken. The
cover 66 of the vessel which is removed for the introduction of the sample tube is
made with a stuffing box, through which a key rod 67 is passed, and when the
vessel 63 is closed with the sample tube 60 inside, the key rod 67 engages with
one end piece 61 of the tube, whilst the other end piece engages with a socket
provided for the purpose in the vessel 63. The water having been made to flow
through the vessel 63 sufficiently long to insure the complete filling of the sample
tube 60, the key rod G7 is turned to screw the end pieces 61 hard up, and then
after the stopcocks of the connecting pipes 64, 65, have been closed, the vessel 63
is opened and the sample tube 60 is removed. If there is any corrosive tendency
in the water in the sample tube 60 it will show itself in a very short time by
corroding the iron rod 62; and if desired the tube may be kept heated so that the
water may be in the same condition as in the boiler. The sample tube 60 may be
fitted with a pipe instead of a rod 62 to admit of its being conveniently heated by
directing a jet of steam into such pipe. A sampling vessel 63, such as has been
described, may be connected to the boiler, or to the feed pipe between the boiler
and an air separator when one is applied externally, or between the air separator
and the feed pumps, or between the feed pumps and the hot well (or feed heater
when one is used), or between the condenser and the air pump, or to any other part,
or two or more such sampling vessels or other modifications of the corrosion
detector may be connected to different parts for the purpose of comparison. In
illustration of the uses of the corrosion detectors it may be stated that in experi-
ments made with them it has been found that water taken immediately from the
condenser of an ordinary surface-condensing marine engine shows little or no
corrosive tendency, whereas when taken after passing the air pump it shows con-
siderable corrosive tendency, and still more after it has passed the feed pumps, thus
corroborating the opinion that it is air absorbed during the passage from the
condenser to the boiler which imparts a corrosive tendency to the water.
Figure 6 is a vertical section of sampling apparatus, in which the external
vessel (63) is dispensed with, the end pieces G1 of the glass tube 60 being screwed
into small boxes 68 formed with branches 64, 65, having stopcocks to be con-
nected to the feed pipe or other part from which the sample of water is to be taken.

page_text: In each end piece there is a screw plug 69, which when unscrewed allows water to
pass to the inside of the glass tube 60 through one or more grooves in the screwed
part and in the ends of the rods 62, but when screwed home the heads of the screw
plugs 69 close the communication. The screw plugs 69 are screwed in or out by
means of keys 67 passing in through stuffing boxes in the boxes 68.
Figure 8 is a vertical section of a modification of our sampling or corrosion
detecting apparatus, in which a thin ring 70 of iron is subjected for a suitable time to
the action of the water passing through the feed pipe 44. The part of the feed pipe 44
is made with opposite stuffing boxes 71, 72, through which tubes 73, 74 of the
same diameter can be passed. One, 73, of these tubes is fitted with a stuffing box
at its outer end, and is formed so that a reduced part 75 of the other tube 74 can
pass through it, and it is also formed with a cavity at its inner end, in which the
iron ring 70 can be enclosed. Stopcock connections are fitted to the outer end of
the lower tube 74, and to the other end of its reduced part 75, to permit of steam
being passed through to heat the detector ring 70, as it is the action of the water
when aided by heat which it is desired to ascertain. When the ring 70 has been
subjected for a sufficient time to the action of the water, the lower tube 74 is
pushed up so as to enclose the ring 70, and then the tubes 74 and 73 are moved
together so as to take the ring 70 out through the upper stuffing box 71, after
which it can be uncovered or be completely removed for examination.
Instead of the corrosion detector apparatus with removable sample tubes (60)
permanent glass detector tubes may be fitted to the various parts thought desirable.
A modification of such a permanent detector is shown in vertical section in Figure 9,
and in it the glass tube 60 is held by means of stuffing boxes in end pieces or
boxes 68, which are attached to a plate or bracket 76, which can be fixed in any
convenient situation. There are stopcock connections 64, 65, at the end boxes 68
for leading some of the feed water through the glass tube 60, and an iron tube 77
to show the corrosive action, if any, is entered into the glass tube 60 through one
of the end boxes 68. This iron tube 77 has one end closed, and a small tube 78 is
passed up it from its other end, whilst stopcock connections 79, 80, are fitted to
the piece 81, holding the tubes 77, 78, in a manner to permit of steam being led
between the outer tube 77 and inner tube 78, and back through the latter, or vice
vered, for the purpose of heating the water in the glass tube 70. The piece 81
holding the iron tube 77 can be uncoupled from the end piece 68, for removing the
tube 77 for the purpose of cleaning or changing it.
By our present Invention we propose to employ zinc in a systematic and
economical manner for obtaining hydrogen to act as an anti-corrosive in the water
of steam boilers, it having been ascertained by us that zinc will yield hydrogen
when placed in heated water (even in a glass vessel.) A separate vessel connected
with the boiler or feed pipe or other suitable part may be provided for subjecting
the zinc to the action of heated water or steam, such vessel being fitted with a
cover and with stopcock connections, by means of which the supply of hydrogen
may be regulated to suit the requirements; or the zinc may be introduced into the
boiler, but in the latter case instead of placing it therein in large quantities in the
wasteful manner hitherto done with the expectation of its affording protection
through galvanic action, it is to be supplied through special apparatus in small
quantities at frequent intervals as it may be required. One mode of introducing
it is by passing it in the form of a rod through a stuffing box, or it may be
introduced in small pieces or in a granular form through a pipe or passage fitted
with two valves, the zinc being entered through the outer valve, whilst the inner
one is closed, and afterwards allowed to pass down through the inner one whilst
the outer one is closed. Figure 10 (Sheet 5) is a vertical section of apparatus
which may be used when introducing the zinc into a boiler in the form of a rod.
A stopcock 82 is fixed to the boiler shell 83, and to the outer part of this stopcock
there is attached by a screw coupling a tube 84, having at its outer end a stuffing
box, through which a handled rod 85 is passed. A rod 86, of zinc, is placed in the

page_text: tube 84, and after this tube has been coupled to the stopcock the latter is opened,
and the zinc rod 86 pushed into the boiler by means of the handled rod 85;
Figure 11 is a vertical section of a simple form of valve or stopcock for introducing
zinc into the boiler in a granular form. The stopcock is fitted with a hollow
plug 87, having an opening at one side only, and when the plug is turned with its
opening uppermost the zinc can be introduced into it through the inlet 88, the
passage 89 to the boiler being then closed. On the plug 87 being turned half
round the inlet 88 becomes closed and the zinc in the plug falls through the
passage 89 into the boiler. A tray 90 is by preference placed in the boiler to hold
the zinc thus introduced.
In withdrawing water from the bottom of a surface condenser through a passage
leading to a feed pump and separate from that leading to the air pump as described
in our earlier Specification hereinbefore referred to, it is sometimes inconvenient to
place the feed pump so low relatively to the bottom of the condenser that the
water will have head enough for easily opening the foot valves. To overcome this
difficulty we, by our present Invention, introduce a steam jet into the pipe or
passage between the condenser and the feed pump, which gives the water sufficient
force for opening the foot valves, even if the pump is placed at a level above that
of the bottom of the condenser; or the water may be raised in any convenient
way so as to acquire the necessary head. Figure 12 is a vertical section of
apparatus for applying the steam jet, as and for the purpose described. The steam
jet nozzle 91 is introduced into the bottom of a box 92, which receives the water
from the condenser 31 by a passage 93, and the water acted on by the jet enters
up through the funnel 94 into a pipe 95 leading it to the required height.
When feed-heating apparatus is. fitted close to the condenser, or even inside of it,
such apparatus may be modified or be supplemented with parts to separate air from
the water, such air-separating parts being substantially such as are referred to in
our earlier Specification herein before referred to; our object being in all cases to
avoid the absorption of air by the water which is fed into the boilers.
In some cases feed injectors may be substituted for the feed pumps hereinbefore
roferred to.
Having thus particularly described our said Invention, and the manner of
performing the same, we have to state that we do not restrict ourselves to the
precise details herein described or delineated, but that what we believe to be novel
and original, and claim as the Invention secured to us by and in terms of the
hereinbefore in part recited Letters Patent is,-
1. The system of feeding steam boilers by means of a pump or injector worked
by steam, the supply of which is controlled by a float, piston, or diaphragm acted
on by the feed water, substantially in the manner and for the purposes herein before
described.
2. The combination with a steam boiler feed pump worked by the main engines
or otherwise of a by-pass valve controlled by a float, piston, or diaphragm acted on
by the feed water, substantially in the manner and for the purposes herein before
described.
3. The application to a steam boiler feed pump of apparatus for altering its
effective length of stroke, such apparatus being controlled by a float, piston, or
diaphragm acted on by the feed water, substantially in the manner and for the
purposes herein before described.
4. The fitting of corrosion detecting apparatus, substantially such as is herein-
before described in connection with a steam boiler or in connection with any part
through which the feed water passes.
5. The employment of zinc to yield hydrogen for the prevention of corrosion in
steam boilers, the zinc being treated with hot water or steam in vessels separate
from the boilers, or being introduced into the boilers in small quantities at regulated
intervals in the manner and by means of apparatus, substantially such as is
herein before described.

page_text: 6. The application of steam-jet apparatus for giving a suitable head or pressure
to water drawn from a condenser to enable it to open the foot valve or valves of a
pump or pumps, and thereby avoid the necessity of placing such pump or pumps
at an inconveniently low level, as hereinbefore described.
In witness whereof, I, the said George Weir, on behalf of myself and of the
said James Weir, have hereunto set my hand and seal, this Twenty-fifth
day of April, in the year of our Lord One thousand eight hundred and
eighty-one.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
GEORGE WEIR. (L.S.)