US668227A - Process of fireproofing wood. - Google Patents

Description

i No. ssa-,227. Patented Feb. I9, Ism.

. H. V. SIMPSON.

-PnocEss 0F FIREPRUUFI'NG woon. (Applicatio med nec. 27, 1899.; (lp lodpl.)

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I l l l WHA/S3551 Nrrnn Srarne Parent HENRY VALENTINE SIMPSON, OF LONDON, ENGLAND.

PROCESS OF FIREPROOFING WOOD.

SPECIFICATION forming part of Letters Patent N o. 668.227, dated February 19, 1901. Application filed December 27, 1899. Serial No. 741,725. (No specimens.)

To all whom, t may concern:

Be it known that I, HENRY VALENTINE SIMPSON, a subject of the Queen of Great Britain, residing in London, England, have invented certain new and useful Improvements in Processes of Fireprooiing Wood, of which the following is a specification.

My invention relates to a method of treating wood for the purpose of making it noninflammable or otherwise preserving it and of introducing coloring-matter into it, if desired. According1 to the method hitherto generally followed for these purposes the lumber to be treated is inclosed in an air-tight receptacle and then heated by direct contact with steam or by means of internal steamcoils or hot jackets for a considerable time. When the wood has been sufficiently heated, a portion of the constituents are withdrawn therefrom and the pores are exhausted of air by a vacuum-pump. Then the chemical solution is admitted and immediately fills the empty pores. The impregnation may be assisted by pressure. This process has under certain conditions given good results; but it has been found to possess the following disadvantages-that is to say, the direct action of heat on wood in the ordinary condition of the latter (either as dry heat or in the form of steam) is liable to aect its structural strength, to darken its color, and to otherwise alter its characteristics. Moreover, the heating adds considerably both to the length of time and to the cost of the treatment. Now my invention relates to the treatment of wood with solutions of the kind hereinafter stated or with other suitable solutions in such manner that better impregnation can be obtained than when live steam or hot air is used in contact with the wood in its ordinary condition, as hitherto, whereby the possibility of injuring or discoloring the wood is avoided and considerable economy of fuel and time is effected. Also when using the solutions hereinafter referred to I am able to introduce into the wood insoluble matter, so as to seal the fireproofing salts in the pores of the wood.

I employ a horizontal cylindrical receptacle with an opening at one or both ends capable of being hermetically sealed by means of doors. The cylinder and doors must be capable of withstanding from two hundred and fty to 'ing solution.

three hundred pounds hydraulic pressure per square inch. In connection with the cylinder I employ an air-pump for creating an exhaust, a pressure-pump for obtaining the necessary pressure, and the usual connections with tanks holding the impregnating solution.

The accompanying drawing illustratesI diagrammatically an apparatus suitable for carrying out my invention.

In the drawing, A is a horizontal c ylindrical receiver provided at one end with an opening adapted to be sealed hermetically by means of a door a. The' cylinder and door must be capable of withstanding from two hundred and fifty to three hundred pounds hydraulic pressure per square inch. The receiver A is provided with a safety-valve b', thermometer c, vacuum gage d, pressuregage e, and blow-off cock f. Within the receiver A are longitudinal rails h, uponwhich the timber 1l to be treated can be run iin on carsj.

B is a vacuum-pump for exhausting the receiver through the pipe h, which pipe is litted with a cock l to open and close communication with the receiver.

C is a pressure-pump communicating with the receiver through a pipe c', adapted to be opened or closed by a cock 2. This pump 'serves to put pressure on the contents of the receiver when required.

D is a tank for containing the impregnat- One tank only is shown; but it will be understood that several may be enlployed. Pipes d d2 d3, adapted to be closed by cocks 3, i, and 5, serve to conduct the impregnating solution from the tank D to the receiver.

E is a boiler for supplying steam to the Ieceiver A when required through the pipe e', which is adapted to be closedby a cock 6.

E is a pump for drawing the solution from the receiver when so desired and returning it to the tank D by the pipes ff2.

7 is a cock in the pipef', adapted to open or close communication with the pump F.

Thewood to be treated (which can be of the ordinary trade sizes and descriptions) if very wet may be first dried to some extent and is placed on the cars j, which run on the rails h into the cylinder A. The door ais then closed and the solution admitted into IOO Aill eifects, for when the Wood has been pregwise.

.the cylinder through the pipes d d2 d3 until the latter is full. Pressure is then applied by the pump C for the necessary time-say ten hours-which depends on the character and dimensions of the Wood. The solution is then returned to the tank D by the pump F.

In the case of soft wood of slight thickness, such as pine one inch to two inches, matchboarding, electric-wire casing, and veneering, the above-specified time will be found sufficient to effect saturation, and the wood can then be withdrawn, and as no steam or other heat has been used the Wood will not be affected in respect of its color or other- Such Woods as one-inch pine I find can be saturated with three hundred pounds pressure in three to six hours. I'n the case of hard woods I prefer a pressure exceeding three hundred pounds, in which case the receiver must be correspondingly strong.

In the case of the harder kinds of wood or greater thicknesses of soft wood only a partial impregnation will have been effected by the above operation, and I therefore continue the treatment as follows, viz: When the Wood is partially impregnated, as above described, the cylinder A may or may not be exhausted by means of the vacuum-pump B. Sufficient live steamis then led into the cylinder from the boiler E to cause ebullition of the solution already in the wood. When the vacuumpump is employed, this ebullition takes place at a low temperature, and the wood is therefore not subjected to an injurious temperature. The effect of this ebullitiou of the solution in the wood is to render the wood amenable for further impregnation. When this ebullition has continued for, say, three or four hours, the steam is cut off (the vacuum being maintained) and the solution is again admitted to the Wood under pressure of the pump O, when the wood will be found to take up a considerably-increased quantity of the solution. In the case of very thick or very hard woods this further treatment may be 'advantageously repeated.

In certain cases I may heat the wood, as above described, without creating a vacuum. The ebullition will then take place at the ordinary temperature of boiling water Without viously partially impregnated even this great heat does not appear to affect it. A characteristic feature of this method is the application of heat to the Wood only after it has been partially impregnated with the solution without heat. There are two well-known methods or processes of impregnation. One of these is known as the double-solution method and consists in impregnating the wood by successive solutions Which cause a reaction on meeting, thereby fireproofing the wood and precipitating in the Wood insoluble matter which cannot be washed out. The disadvantage of this process is the length of time required, the extensive apparatus, and the considerable precipitation formed on the outside of the wood, causing Waste and an unsightly appearance and also injury to any tools that maybe used in working the Wood thereafter. The other, or the single-solution method, consists in using ireproof ingredients which are sollible in Water, the Wood being impregnated with the solution and the Water being driven off` by evaporation, leaving the salts in the Wood.v The disadvantage of the single-solution method is that the ingredients employed, being necessarily soluble in Water, are liable to be Washed out on exposure to the Weather, orif the Wood is subjected to washing` or scrubhing the Wood is also liable to absorb moisture, so that it will corrode metals and will be in other respects inconvenient. Now the ingredients of the solution lem ploy and their proportions are such that I can introduce, as already stated, a desirable proportion of insoluble matter into the wood in a single solution, thus affording practically all the advantages of both the double and single solution methods Without any of the disadvantages appertainin'g thereto. In order to obtain this desirable result, I make use of the property possessed by the combination of certain salts which, although soluble in water at a certain strength, will, on the strength of the solution being increased by the evaporation of the water or other volatile matter, crystallize out as insoluble precipitates. As an example, I may mention the combination of phosphate of ammonia, sulfate of ammonia, and sulfate of zinc in certain proportionssay six, six, and two-in solution with water at a certain strength ofsolution-say sixteen per cent. The wood isimpregnated, as above referred to, with this solution, then the Water of the solution is driven off from the wood by evaporation either in the open air or in kilns, and so the solution in the Wood gets stronger, causing eventually a considerable quantity of an insoluble precipitate. of probably phosphare of Zinc or some compound salt to form throughout the saturated part of the wood, and so sealing the ammonia salts in the pores of the wood. If the solution is used cold and no heat used in the drying off the water of the solution, the sulfate of ammonia may be omitted. Another example is a solution of phosphate of ammonia, sulfate of ammonia, and sulfate of magnesia in the proportions of six, six, and one. In this case the result may be assisted by the formation of phosphate of magnesium, which would take place if any ammonia be set free in the dry rooms or kilns. Still another example is a combination of sulfate of ammonia, sulfate of zinc or of magnesia, and boracic acid in the proportion of ten, six, and four, the boracic acid forming borate of zinc or of magnesia, which is crystallized in the wood on the strength of the solution being increased by evaporation. In order to prevent this last-mentioned solution becoming too acid, I may add a small proportion of potash or other suitable alkali thereto or combine borax therewith. I find the pro- IOC portion of insoluble matter thus formed is, in the above-specied porportions, sufficient to effect my purpose of rendering Wood Waterresisting or non-absorbent,`noninammable, and non corrosive. The proportion may under circumstances depending` on the nature Vof the Wood and the method of impregnation be somewhat varied.

When coloring-matter is to be introduced into the Wood, it may be added to the solution used for rendering the Wood non-inflam- Inable, or if the Wood is to be colored only1 and not rendered non-inflammable a colored solution of any knoWn constituents may ,be used instead of the non-inflammable solution.

I claim as luy-invention the following-defined novel features, substantially as hereinbefore specified, namely:

l. A method of treating Wood to render it non-inflammable by impregnation With a single solution, characterized by impregnating Wood With a solution of ammonium salt and metallic salt, said salts being soluble at a certain strength, but Whicli,\vhen the strength of the solution is increased react and deposit an insoluble precipitate in the pores of the wood Which precipitate seals the non-infiaminable ingredients therein.

2. A method of treating Wood to render it non-inflammable by impregnation With a single solution, characterized by impregnating the wood with a single solution of sulfate of ammonia, phosphate of ammonia, and a metallic salt, said salts being soluble at a certain strength of solution but reacting When the strength of the solution is increased, to produce an insoluble precipitate, then removing suiticient of the solvent to cause the i deposit of said insoluble precipitate in the pores of the Wood, whereby said insoluble precipitate seals the non-iniiammable salts in the pores of the Wood.

3. A method of treatingn Wood to render it non-inflammable by impregnation with a single solution, characterized by impregnating the Wood With a single solution of sulfate of ammonia, phosphate of ammonia and sulfate of zinc, and then removing sufficient of the solvent to cause the deposit of an insoluble precipitate in the pores of the Wood to seal the non-iniiammable salts therein.

4. A method of treating Wood to render it non-in flammable by impregnation With a single solution, characterized by irst impregnating the Wood, before the application of heat, With a solution of ingredients, Which ingredients are soluble at a certain strength, but which, When the strength of the solution is increased, react and deposit an insoluble precipitate, then subjecting the Wood to the action of live steam so as to increase the absorptive powers of the Wood for the solution, then again applying the same solution to the Wood to impregnate it to the required depth, and finally removing sucient of the moisture to cause the deposit of said precipitate to seal the non-indammable salts in th pores of the wood.

5. A method of treating Wood to render it non-in flammable, by impregnation With a single solution, characterized by first impregnating the Wood, before the application of heat, with a single solution of sulfate of ammonia, phosphate of ammonia and sulfate of zinc, then subjecting the Wood to the action of live steam so as to increase the absorptive power of the Wood for the solution, then again applying the same solution to the Wood to impregnate it to the required depth, and finally removing sufficient of the moisture to cause the deposit of the insoluble precipitate to seal the non-inammable salts in the pores of the Wood.

6. The method of treating Wood for rendering :it non-iniiammable and for other purposes, Which consists in depositing in the Wood substances which are non-inflammable and insoluble in Water, then subjecting the Wood to the action of live steam, and then further depositing in the Wood substances which are non-iniiammable and insoluble in Water.

7. The method of treating Wood for rendering it non-inflammable by impregnation with a single solution, Which consists in impregnating it With a solution composed of a mixture of salts Which are soluble in water at a certain strength of solution but Which produce an insoluble precipitate When the strength of the solution is increased by evaporation, and subsequently treating the Wood to evaporate such impregnated solution and thereby effect suoli precipitation in the pores of the Wood.

In Witness whereof I have hereunto signed my name in the presence of two subscribing Witnesses.

HENRY VALENTINE SIMPSON.

Witnesses:

ARTHUR C. FRASER, FRED WHITE.

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