GB2074632A - Cutoff valves - Google Patents

Abstract

A magnetically operated fail-safe cutoff valve 36, particularly suitable for down hole fluid well applications, is provided having a simple highly reliable valve 48, 49 for equalizing the pressure across the main cutoff valve 36 while closed thereby permitting the same to be opened. All operating components can be either removably installed internally of a tubing string or as a portion of the string itself. In either case, typical wire line operations can be conducted through and past the lower end of the cutoff valve since the flow path of each of the illustrative embodiments provides an unobstructed linear flow path therethrough when the valve is open. The pressure equalizing valve includes multiple flow passages 51, 52 and is controlled by a shrouded annular armature 47 operable independently of a tubular armature (not shown) controlling the main valve 36. The two armatures may be located in either a common or separate flux circuits. <IMAGE>

Description

SPECIFICATION Magnetically operated fail-safe cutoff valve with pressure equalizing means This invention relates to cutoff valves.

Down hole safety cutoff valves necessitate provision for re-opening the valve after a shutdown operation utilizing suitable means for equalizing the pressure across the closed cutoff valve.

Recently, valves have been developed employing magnetic means for opening the cutoff valve, as for example, the safety cutoff valves disclosed in our US Reissue Patent 30,110 granted October 9, 1979 and US Patent 4,161,215 granted to Henry A. Bourne Jr. et al on July 17th, 1979. The magnetic cutoff valve shown in our patent relies upon surface equipment to build up pressure above the valve to a value equal to that below the valve whereupon the solenoid can be employed to reopen the valve and maintain it open. Additional surface equipment and time is involved. Bourne et al avoids the need for such surface equipment by utilizing a magnetically operated pressure equalizing facility within their safety cutoff valve.

However, certain of these components are located directly in the flow path thereby precluding wire line operations below the valve, impeding the flow, and subjecting important components to fouling and other hazards.

Other proposals have been made for opening magnetically controlled shut off valves in pressurized flow lines of which the following are typical; US Patents Boyle 1,807,191, Hart 2,693,929, Kramer 2,969,088, Bullard 3,100,103, Van Domelen 3,125,321, Okane 3,381,932, Keller 3,405,906, and Sangl 3,762,683. No one of these constructions with the possible exception of Hart could be installed in a well because the solenoid coil and the armature actuated thereby lie generally normal to the flow path thereby precluding their use in well casings and tubing strings which are subject to severe and rigid cross sectional limitations. Hart is manifestly unsuitable for fluid well applications.

According to the present invention there is provided a valve assembly including a cutoff valve of the type having means for closing the same, and pressure equalizing valve means operable to equalize the pressure across the cutoff valve while closed sufficiently to permit the opening thereof comprising: a tubular housing having an annular chamber all portions of which are stationary and loosely enclosing an armature ring of magnetic material embracing and in restricted communication with the flow passage through said cutoff valve; pressure equalizing valve means operatively associated with said armature ring and provided with inlet and outlet passages in communication with the opposite sides of said cutoff valve; and solenoid coil means embracing said flow passage and operable to shift said armature ring and open said pressure equalizing valve means and permit opening of said cutoff valve.

The present invention enables the shortcomings of the prior proposals to be circumvented by providing a cutoff valve featuring a unique pressure equalizing facility having its own armature and responsive to solenoid coil means which may also operate the main cutoff valve. In,accordance with the teachings of our US Reissue Patent 30,110, all components except the solenoid coil may be detachably installed by wire line in an existing tubing string or the entire valve sub-assembly may form a flow unit of the tubing string itself. Likewise, the features of our new valve assembly can be operated by either single or tandem solenoid operators, the latter type being disclosed in our British Patent Specification No.

2048336A entitled Tandem Solenoid Controlled Safety Cutoff Valve For A Fluid Well. It will therefore be understood that the principles of this invention can be utilized with equal efficiency with either single or tandem solenoid operators.

Typically, the pressure equalizing facility comprises an annular armature ring embracing the flow passage at one end of either a common or separate pole pieces for both a main valve armature and the equalizing armature. Preferably, the pressure equalizing armature operates a plurality of valves each controlling a pressure equalizing flow passage arranged in parallel and cooperating to speed up the pressure equalizing operation as well as to safeguard against malfunctioning if one passage should become fouled. The pressure equalizing armature preferably has an excessive pole face area to develop maximum pull to counteract the well pressure holding the pressure equalizing valves closed. Well pressure is also utilized to provide fail safe closure of the pressure equalizing valve or valves.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a vertical cross sectional view through a first illustrative embodiment of the invention showing a wire line retrievable main valve closed and with the solenoid energized to hold the pressure equalizing valve open; Figure 2 is a fragmentary view on an enlarged scale through the lower end of the cutoff valve but omitting its tubular housing and the solenoid coil; Figure 3 is a view similar to Figure 2 but showing only the lowermost end of the cutoff valve with the pressure equalizing valve in closed position;; Figures 4a and 4b are cross sectional views through a second illustrative embodiment of the invention showing a tubing retrievable main valve wherein the cutoff valve assembly interconnects adjacent sections of and forms a flow unit of a tubing string and showing the main valve closed and the solenoid energized to hold the pressure equalizing valve open; Figure 5 is a fragmentary cross sectional view on an enlarged scale through the lower end portion of Figure 4b and showing both the main valve and the pressure equalizing valve closed; Figure 6 is a plan view from the underside of the pressure equalizing armature for either embodiment; Figure 7 is a cross sectional view of the lower end of a variant of the embodiment shown in Figures 1-3 utilizing separate pole pieces and solenoids for the two armatures; and Figure 8 is a cross sectional view of the lower end of a variant of the embodiment shown in Figures 4a to 6 also utilizing separate pole pieces for the two armatures.

Referring initially to Figures 1 to 3, there is shown a safety cutoff valve assembly, designated generally 10, having a tubular main housing or landing nipple 11 of non-magnetic material with its threaded ends 12, 13 coupled between the adjacent ends of a tubing string 14. This tubing string extends downwardly through a well casing 1 5. Embracing landing nipple 11 is a solenoid coil 16 enclosed in a casing of suitable material 1 7 welded or otherwise secured at its ends to nipple 11. Coil 16 has insulated electrical leads 18 extending to ground level between tubing string 14 and the well casing 1 5. All other parts of the cutoff valve assembly 10 are mounted interiorly of landing nipple 11 as a unitary assembly.

This unitary assembly is detachably connected to the housing landing nipple 11 solely by a fluid tight seal and coupling 20 of well known construction permitting the sub-assembly to be installed and detached with conventional wire line tools. The sub-assembly so supported within the landing nipple includes a collar 21 threaded to the upper end of a coupling 22 secured to a nipple 23.

Suspended from the lower end of nipple 23 is a coupling 24 of non-magnetic material coupled at its lower end to a tubular pole piece 25 of magnetic material. Detachably threaded to the lower end of the pole piece is the pressure equalizing facility 26 of non-magnetic material housing therewithin the moving component of the pressure equalizing valve.

Reciprocably supported within the above described non-magnetic annular components 21 through 24 is a tubular armature assembly designated generally 28, including components 29, 31, 32 and 33. All of these components except armature 32 are of non-magnetic material; 32 being magnetic material. When solenoid coil 16 is not energized, compression spring 34 supports the armature assembly 28 in its elevated or extended position as shown in Figure 1. The lower end of sleeve 33 is then positioned immediately above the closed main flapper-type valve 36 pivotally supported at 37 and urged closed against an annular seat 38 by a spring not shown. It will be noted that armature 32 is then spaced well above the upper end 25a of pole piece 25.As is best shown in Figure 2, the chamber in which valve 36 is housed is cut away along the right hand side as indicated at 39 to accommodate the main valve and to allow sleeve 33 to move downwardly therepast to a position closely adjacent the shoulder 40 near the lower end of pole piece 25. The non-magnetic sleeve 33 then shields valve 36 and seat 38 from contaminants and contact with the fluid flow taking place past the open valve.

The pressure equalizing valve sub-assembly 26 comprises a non-magnetic ring which is detachably coupled to pole piece 25 by threads 42 and is sealed against the end thereof by O-rings 43, 44. The adjacent end face of the sub-assembly 26 is provided with a pair of annular channels 45, 46, channel 45 serving as a fluid distribution channel and channel 46 serving to house and conceal an armature ring 47 of magnetic material.

Projecting downwardly from the underside of armature 47 are a plurality of conical valves 48 which seat against valve seats 49. A plurality of fluid passages 50 extend between channel 46 and the main fluid stream downstream from main valve 36. If valves 48 are unseated fluid escapes from channel 46 through a plurality of passages 51 into the annular fluid distributing channel 45 which communicates with a plurality of passages 52 extending the full length of pole piece 25 and discharge into the tubing string above main valve 36. Typically there are about three passages 50 and these preferably have a cross section smaller than passages 51,52 so that foreign matter which may be present in the well fluid can pass more readily therethrough thereby minimizing the likelihood of particulates accumulating in channel 46.Likewise it is preferable that valves 48 open sufficiently to freely pass particles permitted to enter through passages 50 which are then readily discharged through passages 51,52.

When the solenoid is not energized compression springs 54, assisted by the down hole pressure acting on the cross sectional area of valve seats 49, hold armature 47 extended and valves 48 seated over the inlets to passages 51.

To safeguard against valves 48 becoming misaligned with their seats 49, armature 47 is equipped with a plurality of aligning pins 55 projecting downwardly into cooperating wells 56 opening into the bottom of channel 46. As is best shown in Figure 6, valves 48 are distributed about the armature ring between alignment pins 55.

Referring now to Figures 4a, 4b and 5, there is shown a second preferred embodiment of the invention safety cutoff valve wherein the same or similar components as those described above in connection with Figures 1,2 and 3 are designated by the same reference characters distinguished by a prime. The two constructions differ in only minor respects from one another, the primary difference being that the first embodiment has all components except the solenoid detachably installed interiorly of the landing nipple 11 forming a part of the fluid flow passage of the tubing string 14, 14, whereas in the second embodiment the entire cutoff assembly forms part of the tubing string and is serviced by withdrawal of the tubing string.

Referring to Figures 4a and 4b, it will be noted that the upper end of the cutoff valve assembly 10' is connected to the overlying section of tubing string 14' by a coupling 60 and its lower end is connected to the upper end of the underlying tubing string section 14' by a nipple 61. Also the pole piece 25' interposed between the main valve armature 32' and the pressure equalizing valve armature 47' differs somewhat in structural details but is functionally the full equivalent of the pole piece 25 described above.

Referring now to Figures 7 and 8, there are shown variants of the respective first and second embodiments and differing therefrom in principle and in structure only in minor respects. These differences are confined essentially to the lower end of the assembly and, accordingly, only these lower portions are illustrated. Figure 7 shows a cutoff valve assembly instailable in a tubing string by wire line in the manner described in detail in connection with Figures 1 to 3, and Figure 8 shows a cutoff valve assembly as constructed for installation directly in the tubing string in the manner disclosed in detail in Figures 4a through 6.

Principal structure difference between Figure 7 and 8 and the first described embodiments is the provision of separate pole pieces for each of the armatures separated from one another by a ring of non-magnetic material. The armature for the pressure equalizing valve is also very substantially longer and biased closed by gravity. Another difference resides in the fact that the solenoid coil for Figure 7 is made in two sections each embracing a respective one of the armatures whereas in Figure 8 a single solenoid coil is utilized for both armatures.

Referring now to Figure 7, it will be understood that the same or similar components to those described in Figures 1 to 3 are designated by the same reference characters distinguished by a double prime. The electric coil embracing the landing nipple 11" is made in two sections, the upper section 1 6" embracing the armature 32" being operable to open the main cutoff valve 36" and the second coil section 116 embracing the ring armature 47" located in the annular chamber 46" and provided at its lower end with a plurality of conical pressure equalizing valves 48". The lower end of the main armature 32" comes to rest against the upper end 25a" of the magnetic pole piece 25". This pole piece is coupled to pole piece 125 for armature 47" by a non-magnetic ring 101.

The pressure equalizing valve sub-assembly includes the non-magnetic rings 26" and 126.

Ring 26" is provided with a plurality of passages 50" and 52" cooperating to bleed equalizing fluid from the inlet to outlet sides of main cutoff valve 36".

Referring now to Figure 8, it will be understood that the cutoff valve assembly there shown which has a housing 24"' cooperating with other tubular components not shown interconnecting sections of the tubing string itself 14"'. Accordingly, this cutoff valve is retrievable only by withdrawing the tubing string itself. The same or similar components to those described in Figures 4a to 6 are identified by the same reference characters but distinguished therefrom by the addition of a triple prime. As in Figure 7, pole piece 25"' is connected to the pressure equalizing valve pole piece 225 by a non-magnetic ring 201. The lower end of the pressure equalizing valve armature 47"' is provided with a plurality of conical valves 48"' seating against seats 49"' of the outlet passage 52"'.When the armature 47"' is elevated, the equalizing valves 48"' are open allowing higher pressure fluid to enter chamber 46"' through passages 50"' and to exhaust through passages 52"' into the lower pressure chamber overlying the main valve 36"'.

Operation Since all embodiments are generally similar in construction and function in substantially the same way, a detailed description of one will suffice for all. Let it be assumed that the solenoid coil 1 6 is de-energized so that the compression spring 34 holds the main valve armature 32 and all tubular components assembled thereto elevated or extended to a position slightly above the closed flapper valve 36. The well pressure below this valve will then be communicated to the annular chamber 46 through the several parallel passages 50 with the result that springs 54 and the well pressure will hold the pressure equalizing armature 47 and the attached valves 48 seated over seats 49 preventing well pressure to the inlet to passage 52.In accordance with conventional practice, the well head at the top of the tubing string will be equipped with a Christmas tree provided with a tightly closed valve, not shown.

The operator having ascertained that this last mentioned valve is tightly closed proceeds to energize solenoid 1 6 via leads 1 8. The flux generated by this solenoid will attract the pressure equalizing armature ring 47 in opposition to the forces generated by the well pressure against valves 48 and seats 49 thereby opening valves 48 but will have negligible effect upon the main valve armature 32 owing to the greater forces generated by the same well pressure against the larger area of cutoff valve 36 and holding this valve firmly seated. Once armature ring 47 has been pulled against the end of pole piece 25, the current flow to the solenoid may be reduced.The unseated equalizing valves 48 allow high pressure fluid to bleed from beneath the closed flapper valve to the chamber above this valve via passages 50, 46, 51,45 and 52. Accordingly the pressure differential across the main valve gradually diminishes to a low value. Thereupon the operator sharply increases the current to solenoid 1 6 until the flux generated by coil 1 6 becomes effective to move armature 32 downwardly thereby pivoting main valve 36 counterclockwise to its fully open position. The lower end of the armature 32 will then seat against the upper end 25a of the magnetic pole piece 25 with the lower end of its tubular sleeve 33 almost seated against the bottom of the main valve chamber.Valve 36 is then completely shielded from the continuous linear flow path for the fluid upwardly through the tubing string and valve assembly 10.

Once valve 36 is fully open, the current flow through solenoid 1 6 may again be reduced since a substantially smaller current flow suffices to hold armature 32 retracted against pole face 25a and in position to shield both seat 38 and the main valve 36 via sleeve 33 from fouling or abrasion by gritty or other foreign material in the flow taking place therepast.

Should the power supply to the solenoid fail or should the operator wish to close the valve he merely discontinues the power supply to the solenoid whereupon 34 elevates the armature assembly to its upwardly extended position allowing the torsion spring of the main valve 36 to close the same against seat 38. Likewise armature 47 is extended downwardly by springs 54 so that valves 48 firmly seat against seats 49. The high pressure fluid below the closed main valve is then transmitted to the annular chamber 46 via passages 50 and supplements springs 54 in maintaining the equalizing valves 48 tightly closed.

If the pressure equalizing facility becomes disabled or fails to function upon demand, the safety cutoff valve may be opened by employing surface equipment well known to persons skilled in this art to pressurize the tubing string to a value approaching or equal to the pressure downstream from valves 10 or 10'. The solenoid coil of the safety cutoff valve is then energized and functions to retract the main valve armature thereby opening main valve 36 or 36' and restoring the well flow to a more propitious time for servicing the non-functioning of the on board pressure equalizing facility.

As will be recognized, any of a wide variety of conventional wire line servicing operations may be conducted through the tubing string to levels below cutoff valve assemblies 10, 10'. These operations are carried out while the main valve is open thereby providing an unobstructed path axially of the tubing string with all portions of both the main valve and the pressure equalizing valves and their seats completely shielded from possibility of damage by the wire line or any tools suspended thereon.

Although the two armatures and the flapper valve in the first two embodiments have been shown as spring biased to respective positions it will be understood that no one of these springs is essential. This is because gravity and/or pressure differentials and/or the resistance offered to rapid flow conditions toward ground level may suffice to retract the armature and to close the main valve.

For example, it will be noted that no springs are present in either of the pressure equalizing valves shown in Figures 7 and 8.

While the particular magnetically operated failsafe cutoff valve with pressure equalizing means herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiment of the invention and that no limitations are intended to the detail of construction or design herein shown other than as defined in the appended claims.

Claims (51)

1. A valve assembly including a cutoff valve of the type having means for closing the same, and pressure equalizing valve means operable to equalize the pressure across the cutoff valve while closed sufficiently to permit the opening thereof comprising: a tubular housing having an annular chamber all portions of which are stationary and loosely enclosing an armature ring of magnetic material embracing and in restricted communication with the flow passage through said cutoff valve; pressure equalizing valve means operatively associated with said armature ring and provided with inlet and outlet passages in communication with the opposite sides of said cutoff valve; and solenoid coil means embracing said flow passage and operable to shift said armature ring and open said pressure equalizing valve means and permit opening uf said cutoff valve.

2. A valve assembly as defined in claim 1, characterized in that said solenoid coil means includes an annular pole piece of magnetic material embracing said flow passage and located in the magnetic flux circuit of said coil means.

3. A valve assembly as defined in claim 1 or 2 characterized in said pressure equalizing valve means includes a plurality of sets of valvecontrolled inlet and outlet passages in communication with the opposite sides of said cutoff valve.

4. A valve assembly as defined in any of claims 1-3, characterized in that said solenoid coil means embraces one end of said armature ring.

5. A valve assembly as defined in any of claims 4, characterized in the provision of means for restricting said armature ring to movement axially thereof.

6. A valve assembly as defined in any of claims 1-5, characterized in the provision of means other than said solenoid coil means operable to open said cutoff valve when the pressure thereacross is substantially equalized.

7. A valve assembly as defined in claim 6, characterized in that said means for opening said cutoff valve includes open-ended tubular means forming a principal portion of the flow passage past said cutoff valve when said cutoff valve is open, and said cutoff valve, when open, being movably positioned laterally to one exterior side of said tubular means and shielded from the flow path of fluid therepast.

8. A valve assembly as defined in claim 6 or 7, characterized in the provision of means for automatically closing said cutoff valve upon the malfunctioning and/or non-functioning of said means for opening the same.

9. A valve assembly as defined in claim 8, characterized in that said means for automatically closing said cutoff valve is aided by and responsive to the fluid pressure on the inlet side of said cutoff valve.

10. A valve assembly as defined in any of claims 1-9 characterized in that said cutoff valve and said pressure equalizing valve means are carried by said tubular housing.

11. A valve assembly as defined in any of claims 1-10 characterized in that said pressure equalizing valve means is constructed and arranged to close automatically upon power failure to said solenoid coil means.

1 2. A magnetically operated valve assembly adapted to be opened by equalizing the pressure differential thereacross comprising: a tubular housing adapted to be installed in tubing in communication with pressurized fluid at one end and equipped at its other end with cutoff valve means; main valve means supported crosswise of the interior of said housing movable to an open position providing a linear flow passage which is unobstructed from end to end of said valve assembly; electric coil means coiled concentrically of said tubular housing;; tubular first armature means of magnetic material in axial alignment with the fluid flow passage through said tubular housing, said armature means being reciprocably supported within said coil means movable between the extended and retracted positions thereof and operable to open said main valve means when the pressure thereacross is substantially equalized; and pressure equalizing valve means across small passage means having its opposite ends in communication with the opposite sides of said main valve means and including second armature means of magnetic material positioned to be energized by said coil means and responsive thereto to open said pressure equalizing valve means and thereby effective to equalize the pressure differential across said main valve means.

13. A magnetic valve assembly as defined in claim 12 characterized in that said second armature means comprises ring means encircling the fluid flow path through said tubular valve housing.

14. A magnetic valve assembly as defined in claim 13 characterized in that said pressure equalizing valve means includes a plurality of separate valves distributed about said ring means and each operatively associated with a separate flow passage means in communication with the opposite sides of said main valve means.

1 5. A magnetic valve assembly as defined in any of claims 12-14 characterized in the provision of tubular pole piece means of magnetic material located in the flux circuit of said coil means and toward which said second armature means is attracted when said coil means is energized.

1 6. A magnetic valve assembly as defined in any of claims 1 2-14 characterized in the provision of a tubular pole piece of magnetic material located in the flux circuit of said coil means and toward which said first and second armatures are movable to open said pressure equalizing valve means and said main valve means.

17. A magnetic valve assembly as defined in claim 1 6 characterized in that said tubular pole piece is positioned between said first and second armature means.

18. A magnetic valve assembly as defined in claim 12 characterized in that said tubular housing is securable in alignment with and as a part of a well tubing string, said valve assembly including a tubular pole piece extending coaxially of the interior of said housing opposite one end of said coil means and embracing the adjacent end of said first armature means, and said second armature means being supported adjacent the other end of said tubular pole piece and movable axially toward and away therefrom.

1 9. A magnetic valve assembly as defined in claim 18 characterized in that said tubular pole piece, said main valve means, said first and second armature means and said pressure equalizing valve means are assembled to one another and adapted to be assembled within and removed as a unitary assembly from one end of said tubular housing.

20. A magnetic valve assembly as defined in claim 12 characterized in the provision of means normally biasing said first armature means to the extended position thereof and said main valve means closed, and said pressure equalizing valve means and said main valve means being operable upon the non or malfunctioning of said coil means to close and said first armature means being movable to the extended position thereof.

21. A magnetic valve assembly as defined in claim 1 2 characterized in the provision of means for holding said pressure equalizing valve means in axial alignment for seating in a fluid tight manner in the closed position thereof.

22. A magnetic valve assembly as defined in claim 12 characterized in that said main valve means is selectively operable to open position thereof by said pressure equalizing valve means and alternatively by increasing the pressure on the outlet side thereof to a value approaching or exceeding the pressure on the inlet side thereof.

23. A surface controlled magnetically operated fail-safe cutoff valve assembly equipped with magnetically operated pressure equalizing means comprising: a tubular housing having an open-ended unobstructed linear flow passage axially thereof installable between the opposite ends of a tubing string; main valve means movably supported in said housing for movement between a closed position thereacross and an open position leaving said flow passage unobstructed and free for the passage of wireline supported devices therethrough; tubular magnetic armature means supported axially within said housing and in said fluid flow passage therethrough and biased to an extended position adjacent said main valve means when the latter is closed;; magnetically controlled pressure equalizing valve means operable independently of said tubular armature means having flow connections with the opposite sides of said main valve means; and solenoid coil means operable when energized to open said pressure equalizing valve means and said main valve means in sequence.

24. A safety cutoff valve assembly as defined in claim 23 characterized in the provision of tubular pole piece means in axial alignment with said linear flow passage and serving as a pole piece common to said armature means and to said magnetically controlled pressure equalizing means.

25. A safety cutoff valve assembly as defined in claim 23 characterized in that said pressure equalizing valve means includes an armature ring of magnetic material lying in a diametric plane through said cutoff valve assembly.

26. A safety cutoff valve assembly as defined in claim 25 characterized in that said pressure equalizing valve means is freely and floatingly supported independently of contact with any other component.

27. A safety cutoff valve assembly as defined in claim 26 characterized in that said equalizing valve means is mounted in an annular chamber and is out of contact with the walls thereof.

28. A safety cutoff valve assembly as defined in claim 25 characterized in that said pressure equalizing valve means includes a plurality of valves each operatively associated with a respective fluid pressure equalizing passage bypassing said main valve means and in communication with said linear flow passage through said cutoff valve assembly.

29. A safety cutoff valve assembly as defined in claim 24 characterized in that said tubular pole piece means is positioned between said tubular armature and said armature ring.

30. A safety cutoff valve assembly as defined in claim 24 characterized in that said pressure equalizing valve means is supported within an annular ring of non-magnetic material detachably coupled to one end of said tubular pole piede means.

31. A safety cutoff valve assembly as defined in claim 30 characterized in that said pressure equalizing valve means is positioned between the adjacent ends of said pole piece means and said ring of non-magnetic material.

32. A safety cutoff valve assembly as defined in claim 30 characterized in the provision of guide pin means and cooperating bores between said annular ring and said armature ring cooperable to restrict said armature ring substantially to movement axially thereof.

33. A safety cutoff valve assembly as defined in claim 23 characterized in that said main valve means is mounted in said tubular pole piece means, and a ring of non-magnetic material detachably secured to the lower end of said pole piece means in a fluid tight manner and having an annular cavity for said armature ring.

34. A safety cutoff valve assembly as defined in claim 25 characterized in the provision of guide pin means and bores aligned therewith cooperating to restrict said armature ring means to movement axially thereof.

35. A safety cutoff valve assembly as defined in claim 23 characterized in that said assembly has threaded means at the opposite ends thereof for connecting said assembly between the opposite ends of a tubing string.

36. A safety cutoff valve assembly as defined in claim 23 characterized in that said tubular housing and all portions thereof except said solenoid coil means comprise a unitary assembly adapted to be detachably and operably mounted within and between the opposite ends of a tubing string.

37. A magnetic valve assembly as defined in claim 12 characterized in that said coil means and said first armature means are operable to open said main valve means independently of a disabled condition of said pressure equalizing valve means when the pressure differential across the closed main valve means is substantially equalized.

38. A magnetic valve assembly as defined in claim 12 characterized in that said small passage means in communication with the opposite sides of said main valve means include at least one inlet passage and at least one outlet passage, and said outlet passage being of larger cross section than said inlet passage.

39. A magnetic valve assembly as defined in claim 38 characterized in that said pressure equalizing valve means is movable to an open position through a distance greater than the diameter of said inlet passage to freely pass particulate matter entering through said inlet passage.

40. A magnetic valve assembly as defined in claim 12 characterized in that said main valve means includes means for closing the same as said first armature moves to the extended position thereof.

41. A magnetic valve assembly as defined in claim 40 characterized in that said means for closing said main valve means includes spring means.

42. A magnetic valve assembly as defined in claim 12 characterized in that said first armature means includes spring means normally effective when said coil moans is not energized to move and to hold said first armature means in the extended position thereof.

43. A magnetic valve assembly as defined in claim 12 characterized in that said second armature is positioned and operable to close said pressure equalizing valve means upon deenergization of said coil means

44. A safety cutoff valve assembly as defined in claim 23 characterized in the provision of means for biasing said tubular armature means toward the extended position thereof.

45. A safety cutoff valve assembly as defined in claim 23 characterized in the provision of spring means biasing said main valve means toward the closed position thereof and effective to close the same as said tubular armature means moves to tIle extended position thereof.

46. A magnetic valve assembly as defined in claim 1 2 characterized in that said pressure equalizing valve means includes spring means biasing the same to the closed position thereof.

47. A safety cutoff valve as defined in claim 23 characterized in that said first armature means includes spring means biasing the same toward the extended position thereof.

48. A safety cutoff valve as defined in claim 23 characterized in the provision of spring means operable to bias said pressure equalizing valve means toward the closed position thereof.

49. A magnetic valve assembly as defined in claim 12 characterized in the provision of a separate tubular pole piece of magnetic material operatively associated with a respective one of said first and second armature means and separated from one another by a ring of nonmagnetic material.

50. A magnetic valve assembly as defined in claim 49 characterized in that said electric coil means is formed in first and second sections operatively associated with a respective one of said first and second armature means.

51. A safety cutoff valve assembly constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figures 1, 2, 3 or Figures 4a, 4b, 5 or Figure 7 or Figure 8 of the accompanying drawings.

New claims or amendments to claims filed on 23July1981.

Superseded claims 1 to 11.

New or amended claims Claims 1 to 11 cancelled, remaining claims renumbered and appendencies corrected.