Method of and Apparatus for Impregnating Cellular Substances such as Wood with Fireproofing Preservative and other Reagents in Solution.
Year: 1899

page_text: Date of Application, 28th Feb., 1899-Accepted, 6th May, 1899
COMPLETE SPECIFICATION.
Method of and Apparatus for Impregnating Cellular Substances such
as Wood with Fireproofing Preservative and other Reagents in
Solution.
I, JOSEPH LYBRAND FERRELL, residing at the corner of West Johnson and
Jefferson Streets, Philadelphia, Pennsylvania, United States of America, Mecha-
nical Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascer
tained in and by the following statement:-
In the following description and specification of my invention, I have des-
cribed it with special reference to the accompanying drawings, in which I have
shown a highly organized type of apparatus adapted for the economical working
of my invention upon a commercial scale.
To this end the apparatus is constructed in battery form, and comprises, in
the instance shown, a pair of receptacles, or cylinders, in which the material
may be treated by alternating from one to the other, so as to provide for a
measurable degree of continuity in the action of the apparatus as a whole.
Various automatic appliances to minimize the personal attention required from
the operatives are also indicated. It must be understood, however, that in show-
ing this organized form of a working apparatus, I do not mean to restrict my
broader claims thereto, since the spirit of the invention can obviously be applied
in a simpler type.
The particular application of my method and apparatus which I at present
contemplate, is in connection with the fireproofing of wood, and I will there-
fore simplify the following description by adverting only to such a process, it
being understood, however, that I do not therefore intend to limit my claims
accordingly.
In the drawings, Fig. 1 represents a top or plan view of the apparatus.
Fig. 2 is a longitudinal central vertical section.
Fig. 3 is a transverse section, on an enlarged scale, through one of the cylin-
ders or receptacles in which the wood is treated, and showing the wood in posi-
tion therein.
Fig. 4 is a longitudinal vertical section through a portion of said cylinder.
Fig. 5 is an end view of one of the cylinders, showing the method of con-
struction for closing and opening the head thereof; and
Fig. 6 is a vertical central section through the parts shown in Fig. 5, and on
the line 6, G.
In various systems for impregnating wood with fireproofing material which
have heretofore come under my notice, I have found practical disadvantages,
conspicuously in their effect upon the strength of the wood after it has been
treated, there being a very noticeable tendency to crumble, shred, or split, owing
to the friable character of the fibre after the treatment.

page_text: In various experiments may by me upon this subject, I have been led to
the conclusion that these deleterious results are due mainly to the mechanical
effects of the processes employed upon the wood fibre, rather than to the chemi-
cal action of any particular reagents which are used to impregnate the wood.
In some processes it has been customary to first subject the wood to what may
be termed an exhausting process, with a view to removing the sap or other
soluble ingredients, as a preliminary step to the impregnation with the desired
reagents. This has sometimes been accomplished by the admission of vapor,
under pressure, to the chamber in which the wood was contained, and the sub-
sequent exhaustion of said chamber with a view to allowing the contents of
the wood cells to be blown out, as it were. I believe that this method of
treatment tends to result in the collapse, or, at any rate, the deformity of many
of the cells, thus not only impairing the strength of the material locally, but
tending to destroy the general integrity of the capillary system of the wood.
A further, and perhaps more objectionable, result in the same general direction,
viz., of structural impairment, has been found by me to be due to the use of a
sharply pulsating supply of the fireproofing solution, the usual method being to
pump the solution directly into the receptacle in which the wood is treated. I
find that for commercial practice the wood must be subjected to a high degree
of pressure in order to accomplish an effective and uniform impregnation within
an economical limit of time. At such high pressures the rapid pulsation of a
pump produces the effect of a water hammer, which tends to disrupt the fibres
of the wood, and, moreover, is most severe upon the joints of the apparatus.
My process, about to be described, avoids these disadvantageous results and
yields a product which will be found, after thorough and comparatively rapid
impregnation, to possess substantially the strength of the original fibre.
fire-
I will now proceed to describe in detail the apparatus shown in the accom-
panying drawings, when used in connection with a fireproofing process. The
solution to be employed may be of-any-of-the-well-known-types-for-the
proofing of wood, the preferred and active ingredient, however, being a solution
of ammonium phosphate, which may be used either alone or with other ingre-
dients, as desired. As I do not, however, in the present application claim any
particular solution, and as the action of the process and apparatus is entirely
independent of the character of the solution .e., whether it be a fireproofing
or merely preservative solution, I do not deem it necessary to enlarge upon this
feature.
A A are the receptacles above referred to, in which the wood is completely
inclosed during the saturating process, and which I shall hereinafter term the
impregnating cylinders, but as they are counterparts of one another, I shall
describe the various connections of the apparatus with particular reference to
the cylinder A, which appears in side elevation in Fig. 2.
It is, of course, necessary that the interior of the impregnating cylinder shall
be readily accessible for the introduction of the wood, and at the same time
that there shall be no danger of leakage. To this end I have devised a new
means of applying the cylinder heads. The cylinder A terminates (preferably) at
each end) in short end sections B and B, each of which comprises an internally
overhanging circumferential flange b, and also a vertically extending chamer B.
Upon the chamber B* is mounted an hydraulic cylinder C, having a piston head c
and rod e. At the lower end of the rod is pivotally attached the cylinder
head C, which is adapted to seat itself closely against the inner face of the 5
flange b, and also to be withdrawn by a sliding movement into the chamber B*.
The head is shifted by hydraulic pressure in the chamber C, transmitted to the
valve box d through the pipe e, branching from the pipe E, shown in Fig. 2,
extending from the pressure pump Q, hereinafter described.
D is a controlling valve upon the cylinder C, provided with a depending 5
hand chain, whereby (as shown in Figs, 5 and 6) fluid pressure may be admitted

page_text: from the valve box d to the hydraulic cylinder C, and subsequently exhausted
therefrom through the outlet pipe c. I have described an hydraulic cylinder and
piston as the preferred means for actuating the internally seated sliding cylin-
der head, but obviously, any convenient mechanism capable of shifting the head
may be substituted therefor.
The first step in my process is the introduction of the wood to the impreg-
nating cylinder and the closure of the latter, the piece or pieces of wood being
completely inclosed thereby. The second step in the process is the charging
of the closed cylinder 'with the solution with which the wood is to be impregnated.
In the embodiment of my invention which I have illustrated, said solution is
made, and primarily contained, in the tank F, preferably located above the
impregnating cylinders A A', so that it may flow to said cylinders by gravity.
The pipe G, shown in Figs. and 2, leads to a suitable water supply. The
valve controls communication from the pipe G to the pipe 1, and the latter
leads to the pump I (connected with and operated by the engine J), and the dis-
charge pipe K of the pump I leads thence to the top of the tank F. The pipe L,
extending from the pipe H to the bottom of the tank F, is used as an outlet
for the contents of said tank Fin the subsequent operation, but is provided with
a stop valve 7, which is closed during the initial operation of filling the tank F
with water from the pipe G. The pipes a a', which extend from the pipe If to
the cylinders A A', respectively, are used in the subsequent operation to conduct
the liquid from the pipes L and H to said cylinder. The valves and /', leading
to said pipes a, a are, however, closed during the initial operation aforesaid.
and it is therefore olivious that with the valve in open position, the tank F
may be filled with water from the pipe G by operation of the pump I.
The desired amount of water being delivered to the tank F, the valve is
closed, and, after a solution of the required character has been formed in the
tank F, the valve 7 is opened and the solution permitted to flow from the tank F,
through the pipes L and H and the pipes a a¹, selectively, to the cylinder A or
A containing the material to be treated. The pipes M M serve as air vents
for the respective cylinders A A', being provided with valves m m², respectively,
which are open during the inflow of liquid from the tank F. The cylinder A
having been thus charged with liquid from the tank F, the valves a³ and in
are thereupon closed.
N N are respectively steam supply and exhaust mains. The pipe N serves
to supply the pumps of the apparatus with steam at the proper pressure, and
through the various valve connections, &c., indicated at and the pipes n',
steani is lead from said main end to a steam space 0 (shown in Figs. 3 and 4)
at the bottom of the impregnating cylinder. Said steam space is drained by
the pipes, which, at the opposite extremities of the impregnating cylinder,
lead to the exhaust main N¹.
The aforesaid arrangement of steam pipes, &c., serves as a convenient means
for heating the contents of the impregnating cylinders. Whilst I do not desire
to limit myself to the use of said means, it is desirable that the saturating liquid
shall be heated to a temperature of, say, 160° F., as a convenient and safe
method of attaining expeditiously, but without violence or shock, the necessary
degree of pressure.
P is what I shall term an hydraulic accumulator, consisting (as shown in
Fig. 2) of a vertically disposed cylinder p and a plunger p, adapted to recipro-
cate in said cylinder. A housing extends above the top of said cylinder p
so that the plunger pl may be weighted, as indicated at p³, to any desired pres-
sure per unit of area of the plunger pl.
For the purpose of treating wood as aforesaid, said plunger is weighted
to a pressure of, say, five hundred pounds per square inch, and the cylinder p
is filled with the saturating liquid, at the desired pressure, by means of the
pump Q. The pipe q serves to convey liquid from the tank F to said pump,

page_text: and the pipes q¹ convey the liquid from the pump to the accumulator beneath
said plunger p².
The pump Q is conveniently operated by steam supplied through the pipe q³
from the main N, q3 being the exhaust pipe of said pump leading to the main N¹.
Qis a throttle valve in the steam pipe q leading to the pump, and serves-to
automatically control the operation of the latter through the lever Q2, which is
raised and lowered by the tappets p, p, which rise and fall with the plunger 2¹.
The relation of the parts just described is such that when the plunger is in
the position shown in Fig. 2, steam is admitted to the pipe 2 to operate the
pump Q, and when said plunger is raised by the operation of said pump to the
desired limit,, the tappet 74 contacts with the lever Q2, and, through the latter,
shifts the valve Q₁ into the closed position indicated by the dotted lines in Fig. 2.
I prefer to provide the outlet pipe 26 at the top of the accumulator cylinder,
so that if the pump Q should for any reason continue to operate after the desired
limit of upward movement of the plunger p¹ was reached, the continued opera-
tion of the pump would simply serve to return the surplus contents of the
accumulator cylinder p through said pipe 76 into the tank F.
The accumulator P is connected at the bottom with the impregnating cylin-
ders A. A by the respective pipes A, A, and said pipes are respectively
provided with hand-actuated valves a, a, which are closed during the above-
described steps of the process. To render the action of the apparatus to a cer-
tain degree automatic, I find it convenient to employ check valves v, v (opening
towards the cylinder) in the pipes A2, A3, and when these are used the other
valves, a, a, may be left open during the main portion of the operation. When
the liquid contained in the impregnating cylinder has reached the desired pres-
sure through the rise of temperature, where heat is employed for that purpose,
communication is established between the liquid in the impregnating cylinder
and that in the accumulator, which-latter-should, of course, be under a cor-
responding pressure, so that although the wood under treatment rapidly absorbs
a considerable portion of the saturating liquid, the desired pressure and supply
are maintained therein by the automatic action of the accumulator, the plun-
ger sinking as the liquid flows from the accumulator into the impregnating
cylinder until the tappet p shifts the lever Q2, opens the throttle valve Q', and
causes the pump Q to operate, thus further supplying the accumulator with
liquid at high pressure. When the check valve is employed to control the com-
munication between the accumulator and cylinder, it of course remains closed as
long as the pressure in the cylinder exceeds that within the accumulator, but
when the cylinder pressure falls by absorption of the liquid, the check valve
opens and admits more liquid to maintain the supply.
Although the pump Q may, as aforesaid, be brought into operation after com-
munication has been established between the accumulator and the impregnating
.cylinder, it is to be observed that said pump does not deliver the liquid directly
into said cylinder, but into the accumulator. Thus the pulsations of the pump
are wholly taken up by the movements of the plunger within the accumu
lator, and the water-hammer blows upon the contents of the apparatus are
avoided.
This step in my process, therefore, consists in the maintenance of a quiet
and substantially uniform high pressure of the solution acting upon the wood,
during a sufficient length of time to affect a complete impregnation of the
latter.
Although I have described a particular type of accumulator as a means by
which a continuous supply of the liquid to the impregnating receptacle at a high
and constant pressure may be maintained without shock. I do not desire to
limit myself to said means. It is, however, essential to the preservation of the
cellular structure of the wood that the means whereby the supply of liquid at
high pressure is continued, as aforesaid, during this step of my process, shall be
operative without substantial shock, for the reasons hereinbefore set forth.

page_text: On the completion of the impregnation, the valve a leading from the accumu-
lator to the impregnating cylinder is closed, and the valve h leading from said
cylinder to the pipe H, and the valve m in the air-vent pipe M are opened,
whereupon the pump I is set in operation and the liquid contents of the cylin-
der A are drawn off through the pipes a and H, and delivered into the tank F
through the pipe K.
After the surplus saturating liquid has been removed from the cylinder A, one
of the gates of the latter is opened in the manner hereinbefore described,
and the wood which has been subjected to the process aforesaid is withdrawn
and subsequently dried.
:
As a matter of convenience I prefer to provide both ends of the impregnating
cylinder with the sliding hands, so that the material to be treated may be intro-
duced from the lumber supply at one end and withdrawn at the opposite end for
direct delivery to the drying kiln.
To facilitate the handling of the lumber, I prefer to provide the interior of
the cylinders A A' with tracks s, s, for trucks or cars S, S, as shown in Figs. 3
and 4, upon which the lumber may be loaded exterior to the cylinders and thus
introduced therein. Much time is saved by the retention of the wood upon the
trucks during the process. I find it convenient, therefore, to secure the material
thereon by bands or chains S extending from side to side of the truck frames,
the expansion of the timber during the saturating process being, however, per-
mitted by the spring terminals S2 of said bands. A rail Shaving overhanging
flanges, as shown, is secured along the bottom of the impregnating cylinder and
engages with underhanging rollers upon the truck S, and serves as a conven-
ient means to prevent the mass of lumber and the trucks from floating from the
tracks s, s.
To facilitate the manipulation of the apparatus in the successive
steps of the process, various adjunctive devices may be employed. Thus, I have
indicated upon Fig. 1 thermometers T, T¹, and pressure gauges U, U¹, and, of
course, safety valves V, VI, and devices of that nature may be inserted in the
apparatus wherever convenience may dictate.
It will be observed that in the organization above described, I initiate the
pressure by heating the liquid in the impregnating cylinders, that being obvi-
ously the most rapid and economical method of attaining the desired degree of
pressure in the first instance. I do not, however, limit myself to this particular
method of applying the initial pressure, it being only essential for the conduct
of this step of my process that the desired degree of pressure shall be attained
without substantial shock to the cellular tissue.
Having thus described my invention, I desire to note the following points, by
way of distinguishing it from former processes intended for the same general
purpose:-
-
By dispensing with any preliminary treatment of the wood in the direction of
saturating it with vapor and subsequently withdrawing the liquid contents, and
by directly impregnating the wood with a liquid solution under a high pressure,
applied to the entire surface thereof, said pressure being attained gradually, and
attained and maintained without substantial shock, I avoid all injury to the
structure of the wood and thus preserve to the greatest possible extent the original
strength, durability, and texture.
As a convenient expression to indicate the absence of substantial or injurious
shock which characterizes my process, I designate the pressure as "quietly"
attained, and the supply as quietly maintained.
I am, of course, aware that it is not new, broadly speaking, to treat wood
with a liquid solution in the absence of preliminary vapor treatment, and I do
not broadly claim the same. The dispensing with the preliminary blowing out
of the wood is only incidental to the main principle of my invention, which is,
as before stated, the avoidance. or minimizing of shock and undue strain upon
the cellular tissue,

page_text: As compared with a mere soaking process, my invention presents the great
advantage that I am enabled to use a high pressure, attained and maintained,
as before stated, without shock, and hence to greatly expedite the impregnation
of the wood, and I use the term "high degree of pressure" to distinguish the
relatively great pressure which I am thus enabled to attain rapidly, but without
pulsatory violence, from any of the very low pressure soaking processes, which,
while in one sense avoiding disturbance of the fibre, are so slow and uncertain
as to not only render the process commercially unavailable by reason of the great
expenditure of time, but also yield an imperfect produce, not uniformly impreg-
nated, or, indeed, not impregnated at all in some of the more inaccessible parts.
The distinctions from prior processes, though apparently small as thus stated,
are highly substantial in the results obtained, and I thus advert to them in order
to avoid that confusion which might otherwise exist in view of the vague des-
criptions found in some of the earlier and now abandoned methods. I believe
that I am the first to discover and apply the vital feature of directly treating
the wood with liquid solution at a high pressure under conditions which obviate
what I believe has been universally found to be the disastrous effects of such
pressure.
The use of a very high pressure, preferably in the neighborhood of five hun-
dred pounds to the square inch, is the vital and important factor in successfully
and economically treating wood, where the primary blowing out of the contents
of the cells is dispensed with, and as the utilization of such a high degree of
pressure in vessels of the capacity required for commercial working is a difficult
problem, I have addressed my efforts in the organization of the apparatus em-
bodying my improvements to meeting the conditions necessarily incident to this
method of treatment. The impregnating cylinder must be of large diameter,
and the head must be readily removable. It has been found almost impracticable
to make a tight joint at the heads-in-the-apparatus heretofore employed, and
obviously, any leakage, either there or at any other weak point in the structure,
is at once attended by great diminution of the pressure. Where the cylinder
heads are exteriorly applied in an apparatus having a cylinder, say, seventy-
eight inches in diameter, I do not believe it to be possible practically to preserve
an absolutely tight joint, except by the use of fastening devices so cumbersome
and difficult to manipulate as to require an enormous amount of time and labor
to apply and detach them. Hence the importance of the type of cylinder head
above set forth, which requires no fastening at all, but is so devised that the
internal pressure at once acts as the medium to tighten the joints, and thus
absolutely prevent leakage. Furthermore, as such a cylinder head is necessarily
massive and of great weight, the use of the hydraulic shifting device will be
found a valuable adjunct, since the source of pressure for the hydraulic cylinder
is directly at hand and can be instantly made available. Moreover, the fea-
ture of maintaining the necessary supply of liquid under quiet pressure is not
only of importance in connection with the treatment of the wood itself, but it
is in the highest degree conservative of the apparatus, since nothing is more
likely to cause leakage at any points of weakness than the repeated blows of a
water hammer.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is
1. The herein before-described process of impregnating cellular substances,
which consists in completely inclosing said substances in a receptacle and directly
submitting the entire surface of such substances to the action of an impregnating
liquid gradually heating the solution until a high degree of pressure is
quietly attained within said receptacle; quietly maintaining a supply of liquid
at such high degree of pressure until the desired degree of impregnation has
been attained and finally, withdrawing the substance and drying the same;
substantially as described."

page_text: 2. The combination of an impregnating receptacle, having means for opening
and closing the same, and capable of completely inclosing the substance to be
treated; a reservoir of liquid communicating with said receptacle; a supplying
device as a pump; and appliances, such as an accumulator between the supplying
device and receptacle for maintaining a continuous supply of liquid to the im-
pregnating receptacle without shock to the contents of the receptacle; substan-
tially as described.
3. The combination of an impregnating receptacle having means for opening
and closing the same; a heating apparatus for said receptacle; a reservoir of
liquid communicating with said receptacle: an hydraulic accumulator also com-
municating with said reservoir and with said receptacle; and a supplying device,
such as a pump, intermediate between said reservoir and said accumulator,
whereby a supply of liquid to the receptacle may be maintained through said
accumulator under a definite pressure and without substantial shock to the con-
fents of the receptacle; substantially as described.
4. The combination of an impregnating receptacle having means for opening
and closing the same; a heating apparatus for said receptacle; a reservoir of
liquid communicating with said receptacle; an hydraulic accumulator, also com-
municating with said reservoir and with said receptacle; a supplying device,
intermediate between said reservoir and said accumulator, whereby a supply of
liquid to the receptacle may be quietly maintained through an accumulator
under a definite pressure; a steam supply for said pump; controlling mechanism
for said supply; and a tripping device, substantially as set forth, operatively
engaging with the moving member of the hydraulic accumulator, whereby upon
the rise or fall of said moving member the supply of steam to the actuating
device of the pump may be automatically closed or opened; substantially as
described.
5. The combination with the impregnating receptacle of an externally pro-
jecting chamber arranged at the end thereof; a circumferential inwardly facing
seat arranged around the end of said receptacle; a sliding head adapted to close
against said seat and to be withdrawn into said chamber; and means substan-
tionally as set forth connected with said head, whereby it may be withdrawn.
into said chamber, or permitted to move into position upon said scat; substan-
tially as described.
6. The combination with a pair of impregnating receptacles and means for
closing the same, of a reservoir arranged above the level thereof; supply pipes
leading from the bottom of said reservoir into said receptacle; valves controlling
said supply pipes: heating apparatus for said receptacles; an hydraulic accumu-
lator communicating with said receptacles: valves for controlling said last-
mentioned communication, including a check valve interposed between said
accumulator and said receptacles; a supply pump having its intake in communi-
cation with said reservoir and its discharge in communication with said accu-
mulator; a discharge pump having its intake in communication with said recep-
tacles and its discharge in communication with said reservoir; and actuating
nechanism for said pumps; substantially as described.
7. The combination of an impregnating receptacle, having means for opening
and closing the same; a heating apparatus for said receptacle; a reservoir com-
municating with said receptacle; an hydraulic accumulator also communicating
with said reservoir and with said receptacle; a check valve interposed between
said receptacle and said accumulator; and a supply device, intermediate between
said reservoir and said accumulator, whereby a supply of liquid to the receptacle
may be automatically and quietly maintained through said accumulator in
accordance with any diminution of pressure within the receptacle; substantially
as described.
8. The combination with an impregnating receptacle of a track arranged upon
the bottom thereof, comprising a rail with overhanging flanges; a truck adapted

page_text: to run upon said track and provided with underhanging rollers adapted to engage
with said overhanging flanges; and spring bands connected with said car and
adapted to embrace and secure the contents thereof; substantially as described.
Dated this 20th day of December 1898.
JOSEPH LYBRAND FERRELL.