US2095751A - Blowpipe apparatus - Google Patents

Description

S. B. KIRK Er AL BLowPIPE APPARATUS Filed oct. 28, 1953 MAD/r massa/v INVENTORS 57h/ufr 5.

Oct. 12,1937. s. B; KIRK r AL 27,095,751

BLOWPIPE APPARATUS Filed oct.- 28, 193s 4 sheets-sheet 2 Nfl WYE.

oct. 12, 1931, s ,a KIRK ET AL 095,7 51

BLOWPIBE YAPPARATUS Filed oct. 2s, 193:5 4 sneet-srwt s Oct. 12, 1937. .4 B. KIRK AL r 2,095,751

BLOWPIPE APPARATUS n K y l 'Filed oct. 28, 1935 i Sheets-sheet 4 i m N am@ INVENTORS AORN EY Patented Oct. 12, 1937 UNITED STATES PATENT OFFICE nLowrirE APPARATUS Application October 28, 1933, Serial No. 695,606 17 Claims. (Cl. 15S-27.4)

This invention relates to blowpipes for welding and cutting and like operations where a heating flame may be employed alone or in combination with an oxygen stream for severing or removing surface metal.

Heretofore air, oxygen and a fuel gas have been used in blowpipes to produce combustible mixtures. In such blowpipes no means were provided to quickly obtain or to obtain with precision, the most suitable proportions of the above components of the combustible mixture for the Work to be performed. The mixtures that were produced may not only be unsuitable for the production of the best grade of workbut the mixtures may also be wasteful in the consumption of the gases, particularly the fuel gas.

In such blowpipes, once the approximate proportions of the gases in the combustible mixture were obtained by manipulating two or more valves, the flame at the main nozzle was allowed to burn during the short intervals of time while the flame was not being used and further contributed to the waste of the gases.

Among the objects of the invention are: To

provide improvements-in blowpipe constructions of this character whereby greater efficiency in operation may be attained with greater economy in consumption of fuel gas than has heretofore L been possible with blowpipes; to provide a dependable means for quickly obtaining a com-1v. bustible mixture containing accurate 'proper-f tions of air, oxygen and a fuel gasand to provide a single operative means for controlling the components of said mixture; to provide an im-.

improved arrangement of the operating control mechanism such that all operating control movements may be conveniently effected by the hand` of the operator by,K which he supports the blowpipe; to prevent the continued burning of the heating flame after the blowpipe is dropped or otherwise released by the operators hand; and tootherwise provide an improved, compact, and rugged blowpipe construction.

Other objects and novel features of the invention will appear from the following specification taken with the accompanying drawings, in which,

Fig. I is a view in side elevation of a blowpipe constructed in accordance with this invention;

Fig. II is a top plan view of the blowpipe handle on an enlarged scale as compared with Fig. I and in-which the stem of the blowpipe is broken away and the handle casing is sectioned;

Fig. III is a. bottom plan view of the blowpipe handle with the stem broken away and on the same scale as Fig. I;

Fig. IV is a view in longitudinal section on the line IV--IV in Fig. II;

Fig. Vis a cross sectional view on line V-V in Fig. IV;

Fig. VI is a view in longitudinal horizontal section on line VI-VI in Fig. IV;

Fig.IVII is a cross sectional view on line VII- VII in Fig. IV;

Fig. VIII is an enlarged cross sectional view of the pilot light control valves shown at the left in Fig. IV:

Fig. IX is a detail view of the injector nozzle removed from the blowpipe, and shown in longltudinalsection and on an enlarged scale corpared withFig. IV;

Fig. X is a cross sectional view on line X-X in Fig. IX;

. l Fig. 1U is a fragmentary view in side elevation of the blowpipe head and on an enlarged scale compared with Fig. I;

Fig. XII is a cross section-.1l view on line XII- XII in Fig. XI;

Fig. XIII is a schematic view illustrative of the various passages of the apparatus in their relationto each other and to the various control valves associated therewith as shown in Figs. I to XII; land l f Fig. XIV is a schematic view of a modification of the blowpipe disclosed in Figs. I to XIII.

Most of the principles involved in this invention are applicable to welding'and cutting blowpipes, or the like. However, the blowpipe shown herein Figs. I to m for illustrating the invention is a cutting blowpipe designed particularly for desea-ming purposes. 'Ihe blowpipe may comprise a handle H having blocks B, B', one secured in each end thereof to form supports` for the tubes .passing therethrough and to form valve bodies for the valves which control the passage of gases through the tubes to the head H of the blowpipe. The rear valve block B has connectionsfor air, oxygen and a fuel gas, which gases are mixed in a mixer M builtin the rear block B. 'Ihe flow of the fuel las and the oxygen for heating purposes to the mixer M is controlled by valves Va and V respectively. intermediate the mixer M and the control valves V@ and V", a shut-od valve is inserted in each of the gas lines which may be operated by a lever L. .The lever L and the valves it operates are herein termed a gas saver S. The lever L may be gripped by the hand of the operator while it is holding the handle H to admit the components ofthe combustible mixture to the mixer M from which the mixture is discharged through a tube in the stem S which connects the handle H to the blowpipe head He to which a main burner nozzle N is at tached. The mixture when discharged from the nozzle N may be ignited by a pilot light burner P supplied with fuel gas through valves located in the forward valve block B' on the handle H. When the blowpipe is -used for cutting .purposes the cutting oxygen is controlled by a valve vknob C positioned on the handle opposite to the gas saver lever L. The gas saver lever L, the pilot light valves andthe cutting oxygen valve knob C are so arranged on the handle H that they can all be operated by the members of the same hand which grips the blowpipe handle H.

As shown in detail in Figs. II, IV and VII, the oxygen may be supplied to the blowpipe through a hose nipple O'which is connected to the' cutting oxygen valve chamber 20 in the rear valve block B by a connecting nipple 2| screwed into the end of the chamber. The oxygen for forming the heating ilame is conducted from the cutting valve chamber 20 through a transverse passage 22 in the rear valve block B, as shown in Fig.

- VII. The head 22a of the valve V0 is located in the passage 22 for controlling the flow'of the heating oxygen to the mixer M. Upon opening the heating oxygen valve V0, the oxygen passes from its inlet chamber 22 to the outlet chamber 23 of the valve and through a passage 24 in the ,rear valve body B. The passage 24 is connected to a tube 25 which extends through the handle H and the forward block B in the handle to a cavity 26 in the blowpipe head Ha A re turn tube 25a connects the cavity 26 in the blowpipe head to a passage 21 in the rear valve body -B which leads to the inlet chamber 28 of the ynozzle 33 is screwed into the bore 34 and a groove 35 is cut around the nozzle to provide a chamber 36 to receive the heating oxygen. A transverse passage 3.1 in' the nozzle 33 extends from the chamber 36 and intersects a longitudinal central passage 38 in the nozzle. The central passage 38 conducts the heating oxygen to the mixing point at the end of the nozzle 33. As will be hereinafter described, air and fuel gas are admitted to an annular chamber 39 around the end of the nozzle 33 in the mixer bore 34. The mixer M; icluding the nozzle 33 is so constructed that upon discharging oxygen at a suitable velocity through the central passage 33 a subatmospheric pressure is created at the end of the nozzle 33. The reduced pressure tends to draw air and a fuel gasfrom the chamber 33 around the end of the nozzle and draw these gases into thef oxygen stream.

The fuel gas is supplied to the rear valve body B through a hose nipple A which'is connected to the inlet 40 of the fuel gas control valve body 4l aed'l having an outlet connection which is screwed.

into abore 32 in the rear valve body B. The head 9i of the fuel gas valve Va controls the passage of the fuel gas to the bore 92. A passage 93 having a. transverse and a longitudinal bore formed in block B connects the bore i2 to the inlet chamber 9d of the fuel gas valve d5 of the saver S. `Upon opening the fuel gas valve 35 of the gas saver, the fuel gas passes through a metering plug 36 which is removably secured in the outlet of the valve d5. The plug 46 is provided with an oriceri'l to limit the ow of fuel gas to a transverse passage i8 leadingto the subatmospheric chamber 39 formed in the mixer bore 34 around the end of the mixer nozzle 33.

As shown in Figs. IV and IX, air is supplied to the mixing point at the'end of the nozzle 33 through an opening 49 in a cap or housing 50 attached to the end of the mixer nozzle. A flap valve 5l made of resilient material is provided in the cap 50 to prevent the backward flow, of the gases and permit the inward ilow of air through the cap 50. A partition 5I!a is formed in the cap 59. It divides the cap into an inlet chamber 59b and an outlet chamber 59 for the llap valve 5l. A pair of passages 50d are formed in the partition 50 to permit the ow of air from the inletl chamber Wb to the outlet chamber 50. A rivet 5I secures one end of the flap valve 5I to the outlet side of the partition 50 so that the other end of the valve '5| is normally resiliently held over the passages 50d in thev partition 508, but is adapted to be moved away from the passages by a differential of pressure between the atmospheric pressure in the inlet chamber 5l!b and a lower pressure in outlet chamber 50c, and permit the entrance of air through the passages 50d.

The outlet S communicates with longitudinal passages or bores 54 in the mixer nozzle 33. The air passages 54 extend through the nozzle 33 to the chamber 39 at the end of the nozzle.

The orifice 41 in the metering plug 46 is made of such' a size forthe fuel gas pressure used that the ow of fuel gas through the orice will be so limited that the oxygen jet discharged through the passage 38 in the mixer nozzle 33 will be able to ma'rptain a subatmospheric pressure in the chamber 39 at the end of the nozzle and thereby provide the necessary differential in pressure between the chamber 39 and the atmosphere tov valve 5l and into the chamber 39. Metering plugs 46 having dierent size orices 41 may be interchang'ed one with another to vary the proportionaof air and fuel gasdrawn into the combustible'mixture.

When the oxygen and fuel gas valves 29 and 45 ln. the gas saver S are opened by a mechanism to be hereinafter described, the oxygen llows through the central passage 38 in the mixer nozzle 33 and draws in the fuel gas and air from the chamber 39 at the end of the nozzle 33 and mixes with these gases in the mixer throat 55 which is connected by an expansion chamber 56 to a tube 51 leading from the forward end of the handle H to a. distributing chamber 58 in the head He of -the blowpipe. The main burner nozzle N is connected to the head He of the blowpipe by means of a nozzle nut 59. The mixture is discharged from'- the distributing chamber 58 through the nozzle N in the usual manner and ignited at the end of the nozzle heating flame.

As shown in Fig. VII, the gas saver valves 29 and 45 are of the diaphragm type. They are 4to provide the Consequently,

lregulating valve 16 secured into cavities 6| in the rear valve body B by means of hollow nuts 62 which are screwed into the cavities 6|. The nuts 62 clamp the diaphragm valves 29 and 45 between the ends of the nuts 62 and the bottoms of the cavities 6|. The diaphragm valves 29 and 45 are normally retained on their seats 38 by means of springs 63 compressed between the outer end o'f the hollow nuts 62 and a shoulder 64 on the valve stems 65 of each of the diaphragm valves 29 andi 45. Each of the valve stems 65 is attached at one end to its corresponding valve and the other end of each stem extends through its corresponding hol--` low nut 62. The gas saver valves 29 and 45 are operated by means of the single lever L which is pivoted on a pin 66 mounted in ears 61 on the valve body B. The outer end of each valve stem 65 is provided with a neck 68. The rear arm 69 of the gas saver lever L fits around the necks 68 and is adapted to contact with the stem heads 18 at the outer end of the necks 68 to operate the valves 29 and 45 in opposition to the springs 63. The neck 68 of the stem 65 of the oxygen valve 29 is shorter than the neck 68 of the fuel gas valve 45 and the head 18 of the stem 65 of the oxygen 4valve 29 is thereby placed nearer to' the rear arm 69 of the gas saver lever L than the head 18 of the stem 65 of the fuel gas valve 45. when the forward arm 12 of the gas saver lever vL is drawn toward the handle H the oxygen valve 29 is caused to be opened before and closed after the fuel gas valve 45. This construction of the gas saver S turns the oxygen on before the fuel gas is turned on. The advanced opening of the oxygen valve 29 produces a subatmospheric pressure inthe chamber 39 before or at the time the fuel gas reaches the chamber and the delayed closing of the oxygen valve continues the subatmospheric pressure after the fuel gas valve 45 has closed and thereby preventslthe fuel gas from backing up into either theoxygen passage 38 or passing through the air opening 49 with the attendant danger or annoyance to the operator. The cap valve 5| is also provided to prevent the backward ow of gases through the air inlet 49 and affords protection against flames being discharged through the air opening 49, in the case of a backfire.

A pilot light burner P is provided to ignite the combustible mixture discharged from the nozzle N. As shown in Figs. VI and VII, the fuel gas for the pilot light burner P is supplied from the inlet chamber 44 of the fuel gas valve of the gas saver S through a longitudinal passage 13 in the rear valve 'block B. The passage 13 in the rear valve block B is connected to a passage 14 in the forward block B on the handle I-I by means of a tube extending between the blocks B, B. VAs shown in Fig. VIII, the forward block B is provided with valves for controlling the flow of fuel gas to the pilot burner P. A regulating valve 16 is placed in the passage 14 in the block B'. The regulating valve 16 may be operated to obtain a. reduced idling flamev by inserting a screw driver blade in a slot 11 cut in the valve operatinghead 18 attached to the threaded valve stem 19. A resilient packing ring 88 is inserted between the head 18 and the valve block B'. The ring 88 is adapted to form a seal around the stem 19 and to maintain the valve 16 in the position it may be set.

A by-pass passage 8| around the idling flame is formed in the block B to provide a momentarysupplyof additional fuel gas to the pilot light burner P. The additional fuel gas is used to increase the length of the pilot l idling iiame and ignite the mixture discharged at the end of the nozzle N. A by-pass valve 82 for turning on and off the additional flow of fuel gas to the pilot light burner P is inserted in thel by-pass. 'Ihe by-pass valve 82 is retained in the forward block B' by a plug 83 'screwed into a.

counterbore 84 in the block. The plug 83 is provided with a central bore 85 extending therethrough. The inner end of the central bore 85 communicates with the inlet passage 14 in the block B'. A series of radial openings 86 connect the central passage 8|. A recess is formed around the central bore 85 at its inner end and a valve seat 81 is retained in the recess between the inner end of the plug 83 and a shoulder 88 in the bottom of the counterbore 84. A valve stem 89 unitary with the valve 82 extends through the central bore 85 in the plug 83. A thumb button 98 is screwed to the outer end of the valve stem 89. The plug 83 is provided with a counterbore 9| into which packing and a packing washer 92 is tted around the valve stem 89. A spring 93 encircles the valve stem 89 within the counterbore 9| of the plug 83 and is compressed between the packing washer 92 and the thumb button 98 to` normally retain the valve 82 on its seat 81. tube 94 is connected with the outlet 95 of the pilot valves 16 and 82 in the forward valve block B. 'I'he tube 94 conducts the fuel gas to abracket 96 supported by the combustible'mixture tube 51 at the head end of the blowpipe. The bracket 96 is secured to the combustible mixture tube V51 by clamp screws 91, as shown in Figs. I and XI.

A bore 98 extends through the bracket 96 and is connected with the fuel gas pipe 94 attached to the bracket. A burner nozzle 99 is threaded into the bore 98 in the bracket. A cylindrical shield |88 surrounds the pilot light burner nozzle 99 and is threaded to the nipple |8| around the bore in the bracket 96.

A series of air openings 82 are provided opposite the base of the pilotv light burner nozzle 99 and a series of openings |83 are also provided in the burner nozzle opposite openings |82 in the shield |88 to allow air to be drawn into the central bore |84 in the nozzle and be mixed with the fuel gas.

When the blowpipe is used for cutting .or desear'ning purposes, the cutting oxygenis supplied from the inlet |85 of the cutting oxygen valve chamber 28. The ow of cutting oxygen from the inlet |85 to the outlet |86 of the valve chamber 28 is controlled by a cutting-oxygen valve |81. A seat |88 for the cutting oxygen -valve |81 is screwed into the outlet side oxygen valve chamber 28. The seat |88 is maintained in place by means of the locking ring |89 screwed into the outlet chamber |86 against the valve seat |88. The bore of the outlet chamber |86 is closed by a valve stern bushing I I8 screwed into the end of the chamber. The bushing ||8 is provided with` a central bore into which a valve stem I2 is inserted to actuate the cutting oxygen valve |81. A glandnut ||3 surrounds the outer end of the valve stem ||2 and is screwed to the end of the bushing ||8. Packing ||4 is compressed around the stem ||2 by the nut ||3.

The cutting oxygen valve |81is normally retained bore 85 in the plug 83 to the bypass |86 of the cutting I nally extending knob C attached thereto. The lever l1 is pivoted on a pin H8 in the forward end of a block I I9 in the blowpipe handle H. The lever ||1 actuates a plunger |20' which is slidably supported in the block H9. The plunger |20 actuates the valve stem i l2 and the cutting oxygen valve |07. The longitudinal axes ofthe plunger |20 and the valve stem H2 are arranged substantially parallel to each other. The axis of the plungerv 20'is offset from the axis of the valve stem H2 in the direction of the axis of the handle Hin order to increase the length of the short arm |2| of the lever ||1 and thereby give greater movement to the valve |01.

Upon pressing the cutting oxygen valve knob C, the oxygen passes through the valve seat |08 and into the outlet |06 of the valve chamber 20. A transverse bore |22 conducts the cutting oxygen from the valve outlet |06 to a longitudinal bore |23 in the valve body B to which a tube |24` is connected for conducting the oxygen to a cavity |25 in the blowpipe head He. 'I'he nozzle 4N is provided with the .usual central bore for conducting the cutting oxygen from the' cavity |25 to the end of the nozzle N where it is discharged for use in cutting metal or the like.

A modification of the invention disclosed in Figs. I to m11 is shown diagrammatically in Fig.

XIV. The blowpipe disclosed in Fig. XIV is adapted particularly for welding metals or the like. As shown in Fig. XIV, the fuel gas is admitted to the blowp'pe under sumcient pressure to aspirate the air and oxygen into the mixer M'. The fuel gas is admitted through the nipple A to the fuel gas control valve Va'. A conduit |20 connects the outlet from the fuel valve Va', to the inlet of the fuel gas valve |21 of the gas saver S. A long conduit |20 connects the outlet of the fuel gas valve |21 of the gas saver S' to the mixer M' shown in cross section. The fuel gas conduit |28 is connected to the central passage |30 in the ,|3| which is' screwed into the bore |32 of the mixer M'.

Oxygen under a suitable pressure is supplied to the blowpipe through a nipple O'. The oxygen is controlled by a. valve V0', the outlet of which is connected to the inlet Vof an oxygen valve |33 of the gas saver S' by a conduit |3. A metering plug |35, similar to the plug 46 used in the other modlcation, is placed in theoutlet of the oxygen valve |33 of the gas saver S vand the outlet from this plug |35 is connected to an annular chamber l|31 surrounding the end of the mixer nozzle |3|, .by a conduit |38 extending between the chamber' |31 and the plug |35. In this vmodification the plug |35 in the `oxygen conduit |38 performs the same function as the plug 40 in the fuel gas conduit of the other modification. An air passage |39 is formed in the mixer nozzle |3l.

- It extends through the nozzle 3| and connects the chamber |31 `at the inner end of the nozzle with the air at the outer end of the nozzle. The chamber |31 at the inner end of the nozzle |3| is connected to the mixer throat |40 into which the fuel gas may be discharged from the passage |30 in the mixer nozzle |3| with suiiicientA velocity to create a subatmospheric pressure in the chamber |3`at'the end of the nozzle |3l. Air is drawn through the air passage |39 into the chamber |31 and mixed with the oxygen entering the chamber. The mixture of drawn from the chamber |31 -into the mixer throat |40 and is mixed with the fuel gas to form a combustible mixture. The mixer throat |40 is gas control removable mixer nozzleair and oxygen is.

connected to the main burner nozzle N blowpipe head by a mixture tube ifi l.

A pilot light burner P may be supplied with a fuel gas through a conduit M2 leading from the inlet of the fuel gas Valve |21 of the gas saver S to the burner P'. The idling flame may be controlled by a throttle valve |43. The pilot flame may be increased in length to light the mixture by operating a bypass valve valves being located in the conduit |42 leading to the burner Pf and adapted to function in a manner similar to the pilot control valves shown in Fig. VIII.

The arrangement ofthe operating parts in both ofthe modifications are similar except, of course, in the case of the welding blowpipe, the cutting oxygen valve is omitted.

In the operation of the blowpipe shown in Figs. I to XIII, the blowpipe is connected to suitable sources of gas supply with all of its valves closed. 'I'he fuel gas control valve VEL is fully opened.

in the light idling ame is adjusted and the idling flame is lighted at thev pilot light burner P. 'Ihe heating oxygen valve Vo is opened sufficiently to produce a subatmospheric pressure in the chamber 33 atthe end of the mixer nozzle 33 When the gas saver valves 29 and 45 are opened. The lever L is grasped by the fingers of the operators hand which may be gripping the blowpipe handle H, 'Ihe oxygen discharged through the mixer nozzle 33 draws the air and fuel gas from the chamber 39 around the nozzle. The three gases form a combustible mixture which is discharged at the end of the main nozzle N, Where the mixture may be lighted by pressing the bypass valve thumb button 90 with the thumb of the operators hand which maybe gripping the handle H and the lever L. The heating llame having the characteristcs for which the blowpipe may be designed is obtained by adjusting the heating oxygen valve only. The cutting operated by the operators thumb without changing the position of his grip on the handle H.

The modication disclosed in Fig. XIV is operated in a manner similar to that described in reference to Figs. I to XIII except that the oxygen valve V is rst fully opened and the flame is adjusted by regulating the fuel gas valves Va.

The constructions shown and described herein are illustrative of this invention but it will be understood that changes inthe details as shown may be made without departing from the scope of the invention as dened in the appended claims.

We claim:

1. A blowpipe ccmprising passages for oxygen, and fuel gas; means for forming a combustible mixture containing each of said gases; and a single means adapted to be operated to control the admission of each of said gases to said mixture forming means; and means for admitting atmospheric air to one of said passages, said last-named means being so constructed as to prevent an'outward ow of gases therethrough.

2. A blowpipe having inlets for air, oxygen and a fuel gas; a mixer adapted to form a, combustible mixture containing each of said gases; said mixer the lflow of gas through said passage; said mixer having a passage forming a communication beoxygen valve knob C may be |45, both 0f the tween said chamber and said inlet for air;said mixer having another passage leading into said chamber; a valve for controlling the flow of gas through said latter passage; the inlet of one of said valves being connected to said inlet for oxygen and the inlet of the other valve being connected to said inlet for fuel gas; and a single means adapted to control the opening and closing of said valves.

3. A blowpipe having inlets for air, oxygen and a fuel gas; a mixer adapted to form a combustible mixture containing each of said gases; said mixer having a throat and a chamber in rear of said throat; Aan injector nozzle extending into said chamber and having a passage therein adapted to discharge a gas into said throat and aspirate gas from said chamber; a valve for controlling the ow of gas through said passage; said mixer having a passage forming a communication between said chamber and sa'id inlet for air; said mixer having ano-ther passage leading into said chamber; a metering plug in said latter passage having an orifice adapted to limit the flow of gas 'therethrough to maintain a subatmospheric pressure in said chamber; a valve for controlling the flow of gas through saidilatter passage; the inlet of one of said valves being connected to said inlet for oxygen and the inlet of the other valve being connected to said inlet for fuel gas; and a single means adapted to control the opening and closing of said valves.

4. A blowpipe having inlets for air, oxygen and a fuel gas; a mixer adapted to form a combustible mixture containing each of said gases; said mixer having a throat and a chamber in rear of said throat; an injector nozzle extending into said chamber and having a passage therein adapted to discharge a gas into said throat and aspirate gas from said chamber; a valve for controlling the ow of gas through said passage; said mixerhaving a passage forming a communication between said chamber and said inlet for air; said mixer having another passage leading into said chamber; a valve for controlling the flow of gas through said latter passage; a removable metering plug located in the outlet of said latter valve; said plug having an orifice therein adapted to limit the iow of gas from said latter valve so that a subatmospheric pressure may be maintained in said chamber; the inlet of one of said valves y being connected to said inlet for oxygen and the i inlet of the other valve being connected to said" inlet for fuel gas; and a single means adapted to control the opening and closing of said valves.

5. A blowpipe adapted to form a combustible mixture o-f air, oxygen anda fuel gas comprising Aan oxygen passage and a fuel gas passage; a mixer having a. throat and a subatmospheric pressure chamber connected to -said throat; a removable injector nozzle adapted to discharge one of said gases into said throat and produce a subatmospheric pressure in said chamber; said nozzle having a passage connecting said chamber withl the atmosphere and having a passage com-v gases into said throat and produce a'subatmospheric pressure in said chamber; said mixer having a passage connecting said chamber with the air surrounding the blowpipe; said air passage having a maximum predetermined fixed flow section; said mixer having a passage connecting a source of supply of another of said gases with said chamber; said latter passage having a removable plug therein; said plug having a metering orifice adapted to provide a fixed flow section for `said passage.

7. A blowpipe comprising a mixer for forming a combustible mixture of air, oxygen and a fuel gas; a conduit. for oxygen connected to a source of oxygen under pressure; a conduit for fuel gas connected to a source of fuel gas; a mixer throat; an injector nozzle having a passage therein connected to said conduit for oxygen and adapted to discharge oxygen into said mixer throat; a chamber connected to said mixer throat in rear of the discharge en d of said injector nozzle; said chamber and said injector nozzle being so art ranged that a subatmospheric pressure tends to be formed in said chamber upon the discharge of oxygen through said injector nozzle; an air con"- duit under atmospheric pressure connected to said chamber; a conduit for fuel gas connected to said chamber; a removable plug in said conduit for fuel gas; said plug having a passage therethrough to limit the flow .of fuel gas to said chamber to assist in the maintenance of a subatmospheric pressure in said chamber and determine the ratio of air to fuel gas in the combustible mixture.

8. A blowpipe comprising a handle; a blowpipe head having a main nozzle attached thereto; a mixer for forming a combustible gas mixture; a conduit connecting the outlet from said mixer to said nozzle; a conduit connecting said mixer to a source of combustion supporting gas; a conduit connecting said mixer to a source of fuel gas; a normally closed valve in said conduit for the combustion supporting gas; a normally closed valve in said conduit for the fuel gas; and a common means for opening both of said valves said means being-operable to open said valve in said conduit for the combustion supporting gas before it opens said valve in said conduit for the fuel' gas.

' 9. A blowpipe comprising a handle; a cutting oxygen valve carried by said handle; a valve stem in said handle having its longitudinal axis arranged parallel to the 'longitudinal axis pf said handle; said stein being adapted to operate said valve; a plunger slidably supported in said handle and adapted to operate said stem; the longitudinal axis of said plunger being parallel to the 1ongitudinal axis of said stem and being offset therefrom toward the longitudinal axis of said handle;

a lever pivoted in said handle; said lever having,

an arm adapted to actuate said plunger; and said lever having a second arm extending at substantially a-right angle to said first arm and adapted to be actuated from without said handle.

10. A blowpipe comprising a blowpipe nozzle; a gas` mixer adapted to deliver combustible gas mixture to said nozzle; a conduit for supplying oxygen to said mixer; a conduit for supplyingY 1,2. A blowpipe comprising a blowpipe nozzle; a gas mixer adapted to deliver combustible gas to said nozzle; said mixer comprising a chamber and a mixer nozzle having a passage in communication with said chamber; a conduit for supplying fuel gas to said chamber; a conduit for supplying oxygen to said passage in the mixer nozzle; a conduit for admitting air into one of such gas supply conduits; and a check valve adapted vto obstruct the outow of gas through such air-admitting conduit., I

13. A blowpipe comprising a blowpipe nozzle; a gas mixer adapted to deliver combustible gas to said nozzle, said mixer comprising aV chamber and a mixer nozzle having two passages therein, both passages opening into said chamber; a conduit for supplying fuel gas to said chamber; a conduit for supplying oxygen to one of said passages in said mixer nozzle; and an automaticallyoperable check valve adapted to admit air into 'the other of said passages in said mixer nozzle but obstructing the outilow of gas'through such other 14. A blowpipe having in combination a body provided with a fuel gas passage andan oxygen passage therein; said oxygen passage leading to and discharging into the fuel gas passage; 'a removable metering orlilce member in said fuel gas passage; a removable nozzle and air inlet member establishing communication between one of said passages and the atmosphere; fand a housing member having an air intake passage therel through and having means responsive to pressure tween said spaced points .adapted to secure it therein and having reduced portions adjacent said securing means to form auxiliary chambers with said bore atl said points; a conduit adapted to connect one of said auxiliary chambers witlra central duct within said nozzle; and means for introducing a third gas to said other auxiliary chamber comprising passages extending substantially throughout the length of'said nozzle.

16. Al blowpipe as claimed in claim 15 wherein the central duct within said nozzle emts into said 'other aurnliary chamber at a point beyond the entrance thereto of said other gases.

17. A blowpipe as claimed in claim l5 wherein one Vof said auxiliary chambers is supplied with oxygen, acetylene is introduced to said otherv auxiliary chamber, and air is introduced to said last mentioned auxiliary chamber through passages extending substantially throughout the length of said nozzle. y'

STANLEY B. lWILGQT J. JACOBSSON.

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