US1124555A - Method of exhausting vessels. - Google Patents

Description

CHARLES J. THATCHER, 0F UPPER NYAOK, NEW YORK.

METHOD OF EXHAUSTING VESSELS.

No Drawing.

To all whom it may con cern Be it known that I, (n.mLns J. TI-IATCHER, a citizen of the United States, and a resident of Upper N yack, in the county of Rockland and State of New York, have invented certain new and useful Improvements in Methods of Exhaustmg Vessels, of which the following 1s a specification.

he process which constitutes this inven-,

tion relates to the exhaustion of any vessels whatsoever in which-it is desirable to rapidly and eeonon'iically attain high vacua. It may be used either for exhausting electrical apparatus, which are permanently provided with electrical conductors or terminals, such as incandescent,lamps, vacuum tubes, etc., or for exhausting non-electrical apparatus provided with suitable conductors or terminals only for the purpose of exhaustion.

The object of to attain high vacua in any vessel requiring complete exhaustion, and the invention consists in effecting this in a rapid and economical manner by the use of non-volatilized and inexpensive gas absorbents.

It is well known that complete exhaustion of vessels to high vacua by mechanical pumping alone is a slow and somewhat costly procedure. The difficulty lies in the exhaustion of the last traces of gas.

y invention relates more particularly to the rapid removal of these last traces of residual gases remaining after mechanical exhaustion.

At the present time, so far as I am aware, the only process of rapid exhaustion is that used in the manufacture of incandescent lamps and set forth in U. S. Patent #537,693 to Arturo Malignani. Three stepsare essential to the operation of this process. They are the preliminary mechanical exhaustion of the lamp to a pressure of about 2 mm. of mercury; the intensive incandescence of the filament of the lamp in this attenuated atmosphere and at a sufficient intensity to produce a characteristic faint bluish haze throughout the interior of the bulb; and

lastly, the vaporization of suitable solid substance, such as arsenic, iodin, sulfur, phosphorus, etc.' previously deposited in some convenient locality within the interior of the lamp bulb. The process of said patent also comprises additional elements or steps which I consider tributary to the three fundamentally essential elements above re- Specification of Letters Patent.

this invention is therefore .or removing Patented Jan. 12, 1915.

Application filed March 11, 1910. Serial No. 548,677.

ferred to. These tributary steps have been modified in Letters Patent and in commercial practice, to some degree, as regards the means employed for carrying them out and the sequence of their performance. Otherwise the modern practice of incandescent lamp exhaustion is substantially identical with that devised by Arturo Malignani in 18 4: and disclosed in his Letters Patent.

The'herein described process dilfers from that just considered, in that I secure high vacua without volatilizing any substances, and also in that the intensive incandescence of the filament may, if desired, be dispensed with as an element of the process of exhaustion.

My process may be conveniently described as applied to the exhaustion of incandescent lamps. It is preferably used for the simultaneous exhaustion of a number of lamps or vessels-which is decidedly advantageous and economical-but may be used, if desired, for the exhaustion of a single vessel without deviations from the process as here described other than such as Will be readily devised by workers in the art. After the lamps have been assembled and properly dried as is usual and by any means, I attach them to a vacuum pump or pumps of any description by which a sufficiently low pressure can be obtained. To the same pump or pumps I attach another air-tight vessel which is in free and uninterrupted communication with the pump and the lamp or tions with a considerable quantity of a gas adsorbing solid, preferably one having a as compared to'its large superficial area mass such as lamp black or charcoal. The gas from the entire system is adsorbed or absorbed by these substances in the auxiliary vessel. After once charging it with a considerable amount of a gas absorbentfthe vessel mayv be used over and over again for a number of eXha-usti'ons Without recharging it from the pump connections. It is preferable to maintain the vacuum in the auxiliary vessel between exhaustions by tire system of connections and shutting off communication with the other part of the system by means of a pinch-cock upon a piece of rubber tubing or other suitable means.

The lamps and auxiliary vessel being thus prepared for exhaustion and attached to the pump or pumps, 1 thereupon evacuate the entire system to a suitable low pressure. During this preliminary mechanical exhaustion, it is advisable to pass an electric current through lamps simultaneously and of a suilicient intensity to heat the filaments, the clamps which attach them to the leading-in wires, and any other interior portions of the lamps which may have occluded or which may generate gases, to a suflicient temperature to eliminate practically all of those gases. The object and method of doing this is well understood by workers in the art. since it is almost universally used in the exhaustion of lamps and is technically known as working the filament. Some incandescent lamps or other vessels which may be exhausted by my process may generate so little gas from these sources upon heating or upon the passage of the current that this working may be. dispensed with.

A prcssure which is suitably low, as hereinafter explained, having been attained by mechanical exhaustion, I shut off the com munication with the pump or pumps by any suitable means, such as a pinch-cock upon a piece of rubber tubing in the main pump connection. If the pumps are provided with a practically non-leaking valve, this may be relied upon to effect the aforesaid closure. I now ionize or electrically excite the residual gases or a portion thereof in the auxiliary vessel by any suitable means, such as by the passage of a sufficiently strong electric current through the filament of the auxiliary vessel. The current employed must be of sufficient intensity to produce whatis known as intensive incandescence of the filament, which is usually accompanied by: the appearancevof a characteristic faint bluish haze which at first practically fills the interior of the vessel but disappears'a's exhaustion proceeds. It is well known that the residual gases are,ionized. mostly negatively, by this intensive incandescence. prefer to secure this effect by passine; an electrical current through the gases themselves by means of terminals with which the auxiliary vessel may be provided as already stated. The current necessary for this purpose will depend upon the final'degree of exhaustion desired. The ionization of the res dual gases immediately leads to a rapid reduction of gaseous pressure, not only in but throughout the enlamps. The electrical resistance of the gaseous conductor in the auxiliary vessel accordingly varies the auxiliary. vessel the filaments of all the time, resulting as in gases originally in very high. The voltage used must be sullicientlyintense to overcome this resistance and produce a pronounced luminous discharge in the vessel practically until the desired final gaseous pressure is obtained. This point will be sharply indicated by the disappearance of the luminous manifestations in the same manner as when a solid conductor or filament is used. Any other means of ionizing the interior of the 111):- iliary vessel may be employed; and the residual gases in the lamps themselves may be preferably ionized at the same time by conducting a current of sufiicient intensity through the filaments of all .the lamps to produce the aforesaid characteristic faint bluish haze, now known to workers in the art as intensive incandescencc.

The solid gas adsorbent or viously referred to, such as lamp black or charcoal,should be originally so deposited .in the auxiliary vessel that the ionized gases are immediately exposed thereto. F or this reason I prefer to deposit the gas absorbing solid so that it will be bombarded by the ions or ionized particles which are shot off from the filament of the auxiliary vessel or which traverse the space nals when gaseous conduction is employed.

In the method of lamp exhaustion now in use, the gases are precipitated by a vapor izable solid, such as phosphorus, which is volatilized by heating, whereby the vapor of this solid substance is introduced into the lamp bulb; and it is this vapor, together with the ionization of the gases, which causes the precipitation of the gases and the attainment of the high vacuum.

In my process, the gases are removed by precipitating them upon non-vaporized solids which are preferably placed in a vessel connected with the lamp.

' W'hen the gas absorbing solid in the auxiliary vessel is struck by the ionized clusters of gaseous particles therein they are affixed, apparently by purely physical combine the Malignani process 1n a rapid reduction of pressure. As the result of this removal of gaseous particles from the space within the auxiliary vessel other gaseous particles immediately flow into it from the lamps through the connecting system of tubing. These are in turn ionized and affixed. In this way practically all the gaseous particles of the residual the auxiliary vessel. connecting tubing and the lamp bulbs, which particles were normally free and vibrating in all directions, become aflixed and immovable. Since they thereby lose their energy and impact, the desired nullity of gaseou: pressure, or an almost perfect vacuum, i attained in the entire system. Whether thi explanation is-correct'or not, I find that 1 absorbent premasses glass and the-exhaustion is complete. The.

discarded tubulatures' may then be with- 1 drawn from the pump connections and the 10. inserted. Exhaustion then proceeds as before, except that the pinch-cock on the tub ing leading tov the auxiliary vessel is prefertubules of an unexhausted batch of lamps ably not opened until mechanical exhaustion of the lamp has been completed.- In this way the amount of gas absorbed by the solid in the auxiliary vessel is restricted to those small amounts of residual gases remaining in the lamp bulbs and the connectsuitably arranged air-tight gate ing tubing after preliminary mechanical exhaustion. And the absorbing power of solids of the class specified is so great that if a considerablequantity is introduced initially into the auxiliary vessel, recharging is necessary only after a considerable number of exhaustions.

The gas absorbent solid may be introduced into the auxiliary vessel either through the are used,

or trap. It will be understood that if it is preferable to exhaust individual lamps or other vessels separately the gas absorbing solidmay be introduced into the lamp itself or into the tubulature'or portions connected to the lamps which may be sealed off after exhaus- In this modification of my process the ionization of the gases may be secured by'intensive incandescence of the lamp filaments only, as indeed it may whenever the gases so ionized will come directly into contact with the gas absorbent. I may mention here that most if parently lose their ionizing power rapidly by prolonged intensive incandescence-at least a filament will not readily precipitate the gases after any considerably prolonged use. Where filaments are. relied upon to ioniz'e the gases they must therefore either be new or must be so treated, by flashing for example. that their ionizing power is restored to them.

My process is preferably operated by removing the bulk of the gases by mechanical exhaustion, down to a pressure of 1 to 2 mm. more or less, before precipitating the residual gases by' ionization. Gases at higher or lower pressures than these can be so precipitated when ionized by suitable means. \Vhen substantially new filaments are used there is no difficulty in producing suificient ionization at all pressures from 2 mm. down. If ionization is produced by I and important advantages result.

lamps is considerable.

tubule can .be made shorter, and the savnot all filaments ap e1 increased somewhat, to say 3005 volts, the exhaustion in order to secure a final pressure of..0 20 to .010

From the foregoing description the manner in which my process may be applied to the exhaustion of other vessels than incany exhausting vessels according to the herein described process certain practical Thus it IS economical to dispense with the use of a suitable gas-absorbing substance in exhausting incandescent lamps. Although the process of exhaustion now employed requires the use of a suitable substance such as phosphorus, the total cost of the same and of itsdeposition in the tubules of large numbers of By my process the ing in glass tubing amounts to a further considerable item.

Incandescent lamp exhaustion by my process is also more economical than-the present practice in that it requires less attenticn on the part of the lamp operator and is, in reality, more rapid. A comparatively large number of lamps canbe attached to each pump and the mechanical exhaustion can then'proceed while the operator is attaching or attending to another series of lamps. After the proper vacuum has been reached, as ascertained if desirable by a reading of the pressure by means of a suitable gage attached to each series of lamps, the gases in the auxiliary vessel or the lamps can then be ionized. A determinaticn of the pressure common to all the lamps can be made in a very few secondsby the said gage to insure that the requisite high vacuum has been attained, or the disappearance of the blue haze may be relied upon to determine thispoint. By a suitable arrangement of gas jets the lamps may then all be sealed off simultaneously. The exhaustion of a bank of twenty or more lamps in this manner will not occupy ten minutes all to-" gether, allowing even as much as five minutes for mechanical exhaustion during which the operators attention can be given to another series of lamps. This method of procedure, rapidity of exhaustion and output per operator cannot beduplicated by the present practice of lamp exhaustion, as each lamp requires individual attention and treatment on the part of the operator during the critical portion of the exhaustion.

e gases are precipitated by my process in a more stable and prominent form of comtoward the end of mm. which is con sidered a sufliciently high vacuum for inoandescent lamps.

, itself. The substance,

permanently removed cal exhaustion biiiation than that which results by the present practice and outside of the lamp phosphorus, which is now used, and which holds the gas" in physical combination is vaporized in the lamp bulb at comparatively low temperatures, sufliciently low to liberate'some 0 the gas with Which it is combined. T he temperature which will produce this efl'ect, is easily reached in actual use, particularly after the lamp time. The conditions under which-the combination of theresidual gases with phosphorus originally occurred is not duplicated in actual use.

able reduction in the useful used, for thegases are precipitatedjin combination with practically non-vaporizable particles-such as carbon, and outside of .the lamp itself so that they are e'fiectually'and from thelamp .in-

terior. v

1claim:--- ,1 I 1. The process of rapidly producing high "acuain vessels, which consists in subjectingthem toa suitable preliminary, mechanical exhaustion, andabsorbin' the in a non-volatilized soli .by ionizinggas' particles impinging upon said solid. 2. The process of rapidly producing vessels, which consists in sub ectto a suitable-preliminary, mechaniand absorbing the residual gas in a 'non-vol'atilized, gasabso'rbing solid I by Iil'onizii'ig gas particles contacting there'- Wit ing them hasbeen used, for some considerable -This effect when once start ed is cumulative and results-in a considerlife of the lamp. This effect cannot occur when my process is;

residual gas I 3. The process of rapidly producing high '1 vacua in a vessel containin" i'zed gas-absorbing solid, v

subjecting the vessel to u 'nary, mechanical exhaustion and then ionizing g'as particles in J solids.

vacua in a vessel, 'ing the same to'a'n auxiliar ing subjecting the, former and.

and then ionizing gas iliary vessel to accelerate 5. vacua in an'incandescent preliminary, mechanical v 'the bringing the filament 6. The process i vacua ma vessel consists 1nsub1ecting the preliminary exhaustion,

by the said carbon solid. Signed at 'day'of-Marcg, A. D. 1910..

Witnesses:- LAURA a non-'volatilized' gas- New York, city, New York and State of. Nevv pYork,-this E. s i'm, 'i'FREDK F. Soutm'rz.

thevessel to -:ab sorbtion of the residual gases by the said 4. The process of rapidly 4 Which'con PTO accelerate sists in 'connect-.

y'vess absorbing solid, latter vessel to a suitable preliminary, mechanical exhaustion,

particles, in the auxabsorption oi the d so id -lamp contai non-volatilized gas-absorbing solid, which consists in subjecting; the lamp to a .s ui

vesselto exhaustion, and filament meanwhile, and

to. intensive HARLENSV v a" non-vol ati l ich cons sts in table prel 1111- ducing high el containn n a 7 table