US3819846A

US3819846A - Electrical apparatus with bypass check valve to prevent flow into feeder line

Info

Publication number: US3819846A
Application number: US00355759A
Authority: US
Inventors: W Jakobsen
Original assignee: LOURDES IND Inc
Current assignee: LOURDES IND Inc
Priority date: 1973-04-30
Filing date: 1973-04-30
Publication date: 1974-06-25
Anticipated expiration: 1991-06-25

Abstract

Telephone apparatus comprising a pressurized cable including internal conductors with a cable cover surrounding the conductors and adapted to withstand an internal pneumatic pressure. A pressure-tight case housing electronic circuitry is arranged adjacent the end of the cable and the conductors extend through the cable cover in sealed relationship into the case whereat the conductors are connected to the aforesaid circuitry. A valve arrangement is provided bypassing the portion of the conductors connecting the pressurized cable to the case. This valve arrangement includes a manual control to isolate the case from the pressurized cable and a check valve device to limit the flow of pressure medium from the case back into the cable. The valve arrangement is provided with a valve body and a poppet arrangement, the poppet including an inset adapted for engaging a valve seat in the valve body. The inset is of a material having a hardness of 50-80 on the Durometer A scale. The manual control includes a rotatable part which is made of a fluorocarbon compound. The poppet of the valve arrangement includes a poppet body having a circular skirt which at least in part encircles a helical spring which forces the poppet against the seat provided therefor. The poppet body is provided with a plurality of symmetrically arranged inclined bores arranged in concentric array relative to the skirt.

Description

United States Patent [191 [451 June 25, 1974 Jakobsen 1 ELECTRICAL APPARATUS WITH BYPASS CHECK VALVE TO PREVENT FLOW INTO FEEDER LINE [75] Inventor: William J. Jakobsen, Farmingdale,

[73] Assignee: Lourdes Industries, Inc.,

Farmingdale, NY.

[22] Filed: Apr. 30, I973 [21] Appl. N0.: 355,759

[52] US. Cl 174/11 R, 137/6142, 251/332, 251/333 [51] Int. Cl. H02g F16k 15/18, Fl6k 25/00 [58] Field of Search.... 174/11 R, 15 R, 15 C, 16 R, 174/16 B, 20, 22 R, 23 R, 70 S; 179/170 R [56] References Cited UNlTED STATES PATENTS 2,174,961 10/1939 Bennett 174/11 R 2,501,305 3/1950 Bennett 3,571,486 3/1971 Kennedy 174/11 R Primary Examiner--Laramie E. Askin Attorney, Agent, or Firm-Roberts & Cohen [57] ABSTRACT Telephone apparatus comprising a pressurized cable including internal conductors with a cable cover surrounding the conductors and adapted to withstand an internal pneumatic pressure. A pressure-tight case housing electronic circuitry is arranged adjacent the end of the cable and the conductors extend through the cable cover in sealed relationship into the case whereat the conductors are connected to the aforesaid circuitry. A valve arrangement is provided bypassing the portion of the conductors connecting the pressurized cable to the case. This valve arrangement includes a manual control to isolate the case from the pressurized cable and a check valve device to limit the flow of pressure medium from the case back into the cable. The valve arrangement is provided with a valve body and a poppet arrangement, the poppet including an inset adapted for engaging a valve seat in the valve body. The inset is of a material having a hardness of 50-80 on the Durometer A scale. The manual control includes a rotatable part which is made of a fluorocarbon compound. The poppet of the valve arrangement includes a poppet body having a circular skirt which at least in part encircles a helical spring which forces the poppet against the seat provided therefor. The poppet body is provided with a plurality of symmetrically arranged inclined bores arranged in concentric array relative to the skirt.

12 Claims, 7 Drawing Figures PKESS URI 2 E D ELECT PATENTEDJEIH 25 I974 SHEET 1 0F 2 FIG.

PR/OR ART PRESSUR/ZED PAlEmimunzs I974 sum ear 2 ELECTRICAL APPARATUS WITH BYPASS CHECK VALVE TO PREVENT FLOW INTO FEEDER LINE FIELD OF INVENTION This invention relates to telephone cable equipment and the like and, more particularly, to equipment and valves to operate with pneumatically pressurized cables and apparatus connected thereto.

BACKGROUND Subterranean telephone installations and the like frequently involve the use of pressurized cables or, in other words, cables of the type which is provided with a cable cover impervious to pneumatic media and capable of accommodating therein a plurality of conductors. These conductors are protected from the environment and, more particularly, from the penetration of water, gases and spurious chemicals and contaminants, which may be corrosive or otherwise harmful to the conductors, by supplying a pressurized medium such as air to the cables so that the pressure within the cables operates to prevent the penetration of foreign substances.

It is also known, with respect to telephone installations and the like, that it is frequently necessary to connect thereto pieces of electronic equipment. Thus, where pressurized cables are involved, it is necessary to make an accommodation between the pressurized cables and the apparatus to be connected thereto. For example, it is known to provide, along an extended length of telephone cable, a series of repeaters or amplifiers which are utilized to amplify or boost the signal being transmitted along the cable. Thus, it is necessary to couple pressurized cables to these repeaters and to make accommodations as between such cables and the repeaters connected thereto.

In the Cable Maintenance Handbook published by New York Telephone Company (issued by Operating Staff Plant) Dec. 1970, Section 640-525-l06, there is disclosed an example of a pressurized cable connection to an associated apparatus case. This apparatus case includes a detachable cover which, when placed on the case, forms a pneumatically and hydraulically sealed unit which is attached to a pressurized cable. One difficulty which has been found with respect to the available construction is that no protection is provided against reverse flow. As a result, while it is possible for a pressure medium to flow from the pressurized cable into the apparatus case, it is also possible for pressure media to flow from the apparatus case back into the cable. During installation periods, it is possible for water or moisture to enter the apparatus case and, when the apparatus case is reattached to the cable after maintenance, the moisture flows backwardly into the pressurized cable and operates corrosively on the conductors included therein. Even worse, the moisture can penetrate into the associated system.

In connection with the aforesaid defect, it has further been found that when a cover is replaced upon the associatedcase, the original seal is-frequently not restored. The reason for this isthat an O-ring is involved in this seal which should be replaced but frequently is not, whereupon an imperfect seal results. This permits the penetration of moisture through the imperfect seal back into the pressurized cable.

Another difficulty with available equipment is that such equipment is provided with a cutofi valve operative between the pressurized cable and the apparatus case. Cutoff valves of the type previously employed have a high rate of failure since they are very susceptible to galvanic corrosion and chemical attack. Accordingly, the available apparatus is further unsatisfactory in this regard.

Another difficulty with available equipment is that the cutoff valve mentioned hereinabove is provided with no visual indication of when the same is open or closed. Consequently, when a maintenance operation ensues, it is not readily possible to indicate that the valve has been appropriately opened to connect the apparatus case with the pressurized cable. This results in difficulties as regards servicing the massive amount of equipment which is employed in connection with telephone installations and the like.

Another deficiency of the available equipment is that only a restricted flow is afforded between the pressurized cable and apparatus cases attached thereto. This results from the fact that a restrictive mechanically controlled valve having a screw thread is employed. This not only restricts the flow but furthermore is susceptible of corrosion and failure as has been noted hereinabove.

SUMMARY OF INVENTION It is an object of the invention to provide for an improved coupling of pressurized cables and associated apparatus or electronic circuitry.

It is another object of the invention to provide an improved valve arrangement for the above-noted type of apparatus which provides protection against reverse flow and against the penetration of moisture into a pressurized cable from an associated apparatus case even though such apparatus case may not be properly sealed.

Still another object of the invention is to provide for an improved coupling of a pressurized cable and apparatus case possibly including electronic circuitry therein, which coupling is less susceptible to failures that might be caused by maintenance personnel and the like.

Yet another object of the invention is to provide an improved valve construction for use in coupling a pressurized cable with a piece of associated electronic equipment.

The above and other objects of the invention are achieved by the provision of a device comprising a pressurized cable including internal conductors and a cable cover surrounding these conductors and adapted to withstand an internal pneumatic pressure. The pressurized cable is connected to a pressure tight case including electronic circuitry therein. The conductors include a section extending into the case and in sealed relationship out of the aforesaid cable cover. These conductors are connected to the electronic circuitry in the case.

In further accordance with the invention, there is provided a valve means bypassing the aforesaid section of the conductors and connecting the pressurized cable to the case and including both manual control means to isolate the case from the cable and check valve means to limit the flow of a pressure medium from the case back into the cable. The manual control means permits servicing the circuitry in the case.

According to a feature of the invention, the bypass valve comprises a valve body provided with a bore extending therethrough, this bore having an enlarged chamber at one end thereof. An end cap member provided with a bore is fixed in the aforesaid chamber to confine an inner chamber therein, said bores and inner chamber cooperatively forming a flow passage. A poppet is provided in said inner chamber. Said end cap member includes a seat protruding towards said poppet and encircling the bore in said member. Said poppet includes a poppet body and a poppet inset in said poppet body, said inset having a hardness of 5080 on the Durometer A scale and being adapted to engage the aforesaid seat. A spring is positioned in said inner chamber urging said poppet and thereby said inset against said seat whereby to cut off flow through said flow passage.

In addition to the above and in further accordance with the invention, a cutoff means is provided in the valve body to cut off flow in the bore in the valve body. This cutoff means includes a rotatable part rotatable about an axis perpendicular to the bore in the valve body and having a diametral bore selectively alignable with the bore in the valve body.

In accordance with a feature of the invention, the rotatable part is a fluorocarbon compound and preferably the compound known as Rulon. According to a further feature of the invention the aforesaid inset is preferably of a fluoroelastomer and has a hardness of 70-80 on the Durometer A scale.

Preferably, the aforesaid seat is a circular rim with a thickness in radial direction of 0.005 0.010 of an inch. Moreover, the poppet body includes a circular skirt at least in part encircling the associated spring and is provided with a plurality of symmetrically arranged inclined bores arranged in concentric array relative to the associated skirt.

According to a further feature of the invention, an indicator is provided which is external of the valve body and is connected to the rotatable part.

In accordance with yet another feature of the invention, a pin extends through the valve body and into the aforesaid end cap member to lock the latter to the valve body. Furthermore, a retaining ring is provided to hold said rotatable part in said valve body, said valve body being preferably of brass or stainless steel and said pin and ring being of stainless steel.

According to still another feature of the invention, the valve body is of metal and is coated with a primer coating of epoxy-polyamide and a coating of polyurethane on the primer coating.

According to an important feature of the invention, the inset in the poppet body may preferably be of Viton."

The above objects and features of the invention will be more readily understood from the detailed description which follows hereinbelow as illustrated in the accompanying drawing.

BRIEF DESCRIPTION OF DRAWING In the drawing:

FIG. I is a perspective view of a pressurized cable and apparatus case arrangement provided in accordance with the prior art;

FIG. 2 is a diagrammatic illustration of the connection provided between a pressurized cable and associated apparatus case with the inclusion of a bypass valve, the diagram being applicable both to the prior art and to the instant invention;

FIG. 3 is a side sectional view, partially broken-away, of a bypass check valve provided in accordance with the invention and employed in the apparatus diagrammatically illustrated in FIG. 2;

FIG. 4 is a bottom view of the valve illustrated in FIG.

FIG. 5 is a side view of an end cap element of the valve illustrated in FIG. 3;

FIG. 6 is a side sectional view of a poppet element employed in the valve of FIG. 3; and

FIG. 7 is an end view of the poppet member illustrated in FIG. 6.

DETAILED DESCRIPTION FIG. 1 is a perspective view of apparatus provided in accordance with the prior art. This figure illustrates a unit including an apparatus case furnished with a socalled stub cable which may be furnished, for example, in a length of from ten to forty feet. Both the cable and the apparatus case are pressurized and are additionally electrically connected by a connection which is by-passed by a valve.

More particularly, FIG. 1 illustrates an apparatus case 10 including a cover 12 adapted to be fastened thereon by means of a lock 14. Within the apparatus case 10 may be enclosed electronic circuitry such as a repeater or amplifier or booster suitable for amplifying or boosting signals passing through a cable in a telephone installation, which may be a subterranean installation.

Connected to the apparatus case 10 is a loop of pressurized cable 16. This pressurized cable is provided with an external cover which is generally impervious to pneumatic media and fluids, except when torn or otherwise damaged. The cable is also provided with internal conductors which pass through the end of the cable and through the cover 12 into the apparatus case 10 wherein these conductors are connected to an electronic circuit.

The pressure medium introduced into the cable 16 is preferably also introduced into the apparatus case 10 in order to withstand the penetration of moisture, gases, water and corrosive and/or chemical substances or the like which might act on the conductors or interfere with the operation of the circuitry within the case 10. The arrangement, as will be shown, is such that a terminal portion of the conductors extends through the end of the cable 16 and thence through the cover 12, with a pneumatic connection between the cable 16 and the case 10 proceeding separately and in parallel to the terminal portion of the conductors by means of a bypass valve 18.

In the prior art, this valve is a mechanically controlled screw-thread valve which is susceptible of corrosion and the subject of frequent failure. In addition, this valve offers no protection against reverse flow (i.e., from the case 10 to the cable 16) so that, should there be a leak in the case 10, moisture, water and so forth can flow back into the cable 16 and penetrate into the entire system to which the cable 16 is connected. This most frequently occurs when the case 10 has its cover 12 removedfor servicing since, at this time, an O-ring seal is disturbed which should be, but frequently is not, replaced. As a result of this, when the cover 12 is replaced on the case 10, an imperfect seal results through which water and the like can penetrate to contaminate the interior of the cable 16.

FIG. 2 diagrammatically illustrates the apparatus which is described above and which forms the basis for the improvements of the invention. Thus, for example, there is in FIG. 2 a pressurized cable 16, a pressurized case 10, a cover 12 on the case 10, and a bypass valve 18 serving to connect the interior of the cable 16 with the interior of the case 10.

More particularly illustrated in FIG. 2 is a cable cover 20 which is impervious to pressure media and which encircles and internally accommodates a plurality of conductors 22. The conductors 22 include a section 24 extending through the end 26 of the cable. The cable is provided with a plug 28 which maintains the integrity of the cover 20 and permits the conductors 22 to exit from the cable 16 without any loss of pressure.

The sections 24 of conductors 22 extend as indicated by arrows 30 into an electronic circuit 32. The electronic circuit 32 may, as aforesaid, be a repeater, an

amplifier, or' a booster, or the like. Signals present on the conductors 22 are amplified by circuit 32 and returned into the telephone system by means of selected of the conductors 22.

The interior of the cable 16 is connected to the pressurized case 10, as aforesaid, by means of the valve 18. This valve is therefore a bypass valve, since it operates to bypass the terminal portion of the cable 16 and the sections24 of the conductors 22. In previously known constructions, the valve 18 was a simple, mechanically controlled screw-thread type valve which was frequently subject to failure and which could not operate to prevent leakage into the case 10 from penetrating back into the interior of cable 16 and thence into the system coupled thereto. In accordance with the invention, however, an improvement is made in the valve 18, which reflects in an improvement on the overall system in that both a manual valve control is provided to enable the cover 12 to be detached from the case 10 for purposes of servicing and in that there is provided a check valve function which prevents any leakage into the case 10 from entering the interior of the cable 16. As a result, the case 10 is effectively isolated from the cable 16 in the reverse direction of pressure medium flow.

FIGS. 3-7 illustrate the bypass check valve which is employed as the valve 18 in FIG. 2 to obtain the various advantages and objectives of the invention.

FIG. 3 more particularly illustrates a valve body 40 provided with an internal bore 42. The internal bore 42 widens at one end thereof into a chamber 44, which receives the section 46 of an end cap member 48. To member 48 is connected a pipe 50 by means of which pneumatic medium travels from the aforesaid cable into the case 10 as indicated by arrow 52.

The body 46 sustantially closes off the chamber 44 to form an inner chamber therein. Access to this inner chamber is gained via the bore 54 provided in the member 48. Bore 54 has a widened section 56. Within the inner chamber portion of chamber 44 is a poppet 58.

66 of the pipe 62 is offset from the bore 42 for purposes of convenience in mounting.

Downstream of chamber 44 is located a rotatable part 68 provided with a diametral bore 70. This diametral bore is adapted for being controllably aligned with the bore 42 for purposes of selectively permitting flow through the valve or cutting off this flow, as desired. The rotatable part 68 is provided with a slot 72 into which penetrates a ridge 74 on an actuator member 76. The actuator member is retained in the valve body 40 by means of retainer rings 78.

A visual indicator 80 is connected to the actuator 76 by means of a connecting rod 82. Rotation of the indicator 82 therefore rotates actuator 76 which, in turn, rotates the rotatable part 68, thereby to bring the diametral bore into alignment with the bore 42. The indicator is manually operated and this provides for manually cutting off the bypass check valve of the invention, thereby to isolate the cable 16 from the case 10 and permit servicing of the circuitry within the case 10.

The indicator 80 is shown more clearly in FIG. 4, wherein can be seen, below the body 40, a triangularshaped member or arrowhead which can indicate to maintenance personnel whether the valve is open or closed. This advantage has not been heretofore provided in bypass valves of past telephone systems, which has resulted in much loss of time due to the massive amount of equipment to be serviced.

FIG. 5 illustrates, on enlarged scale, the end cap member 48 employed in the apparatus of FIG. 3. Herein can be seen that a rim is provided protruding from the body 46. Said rim has a sloped slide forming a truncated conical portion, the angle A of which is approximately 30 and may vary, for example, between limits of 20 and 50.

The radial thickness of the rim 90 is indicated at 92. This dimension has been found to be rather critical for operating with the poppet which will be described in greater detail hereinafter. Dimension 92 is preferably 0.005-0.010 of an inch. If the rim is of lesser breadth, it operates as a knife edge. If the rim is of greater breadth, it does not operate effectively with the poppet and particularly with the material to be mentioned in greater detail hereinafter.

A feature of the invention resides in the comparative diameters of bore 54 and widened section 56. The purpose of this increase in area is for fast crack opening and to provide rapid rising critical pressures to the associated poppet member.

Another critical dimension of the end cap member 48 is indicated at 94. This dimension is the height of the rim 90, which preferably equals 0.015 plus or minus 0.005 of an inch. This dimension is critical with respect to preventing the bottoming out of the associated poppet.

Further attention is directed to the throat 96 in the end cap member 48. This throat is provided to accommodate the O-ring 98 illustrated in FIG. 3.

In FIG. 3 is more particularly illustrated the pin 100.

This pin penetrates through the body 40 in radial direction and enters a bore provided in the end cap member body 46 for purposes of retaining the latter in position.

FIGS. 6 and 7 illustrate the poppet member employed in accordance with the invention, and more particularly, the poppet 58 illustrated in FIG. 3. In FIGS.

6 and 7, the poppet is seen as comprising a poppet body 110 from which depends a circular skirt 112. The poppet body is provided with a depression 114 in which to receive the poppet inset 116, which is a symmetrical and circular disc-like member in shape.

A plurality of inclined bores l 18 are provided in circular array concentric with the axis 120 of the valve, and thereby concentric with the skirt 112. The inset 116 is adapted for being urged, by the abovementioned spring 60, against the circular seat which is formed by the rim 90 on the end cap member 48.

The valve which has been described hereinabove is representative of a vast improvement in the by-pass employed in the pressurized cable system described hereinabove. The valve of the invention is further substantially improved by the use of proper materials to form the above-mentioned parts. Thus, for example, the inset 116 is preferably of a synthetic rubber of fluoroelastomer material having a hardness of 50-80 on the Durometer A scale and preferably a hardness of from 70-80 on this scale. The preferred material which is employed for manufacturing the inset 116, is Viton manufactured by Dupont and and identified as V747. As disclosed in C. E. Conover and Co., Inc. catalogue entitled Viton," Viton" is a high performance synthetic rubber possessing exceptional heat and fluid resistance and having an excellent combination of resilience with heat, fluid and abrasion resistance. It is also resistant to flame radiation, high-vacuum outgassing and ozone. It has a tensile strength of 1,735 psi in its original form with an elongation of 190 percent. It is especially adapted to seat against stainless steel and brass valve seats which, as will be explained below, are the preferable materials from which the body 40 and the end cap member 48 are fabricated.

The rotating part 68 described hereinabove is preferably fabricated of a self-lubricating material such as Teflon" or Rulon. Teflon is a fluorocarbon compound and Rulon is a fluorocarbon compound supplemented by other inert ingredients as described, for example, in US Pat. No. 3,122,505. Rulon LD and Rulon .l are both preferably employed in accordance with the invention, and offer respectively a low deformation under compressive loads for valve seats and heavily loaded applications as well as operation against very fine finishes of stainless steel. The use of Rulon for purposes of fabricating the rotating part 68 provides a valve which is free from the danger of freezing and therefore reduces the possibility that the valve of the invention will fail in comparison with previously available valves employed for the described purpose.

In addition to the above, it has been indicated that the valve body 40 and the end cap member 48 are preferably made of either brass or stainless steel. If brass is employed, the retainer spring 78 and the pin 100 are nevertheless made of stainless steel in order to achieve maximum reliability.

As a further feature of the invention, the valve body and associated parts are preferably provided with a special prime coating and an outer coating thereupon. The primer coating is preferably epoxy-polyamide according to military specification M|LrP-23377C of Aug. 26, 1969. This specification sets forth a chemical and solvent-resistant primer coating which is now found to be especially suitable for use in the type of telephone cable systems in which the invention is adapted to be used.

Over the aforesaid primer coating is provided an aliphatic polyurethane coating according to military specification MIL-C-S 1773(AS). This specification defines a finish now found suitable for use in circumstances where corrosive action to be avoided in telephone systems; The special application of the coating in connection with the instant invention provides definite and significant improvements as regards telephone cable systems of the pressurized type.

From what has been stated above, it will now be seen that there is provided in accordance with the invention an apparatus involving the use of a pressurized cable including internal conductors and a cable cover surrounding the conductors and adapted to withstand an internal pneumatic pressure, there being a pressuretight case with electronic circuitry therein coupled to the conductors in the cable. These conductors, as has been seen, include a section extending in sealed relationship out of the cable cover into the case and being connected to the aforesaid circuitry. There is also disclosed herein a valve means by-passing the aforesaid section of conductors and connecting the pressurized cable to the case and including both a manual control means to isolate the case from the cable and a check valve means to limit or prevent the flow of a pressure medium from the case back into the cable. There have also been set forth the critical materials and dimensions of the inset 116, as well as the rotatable part 68, and the seat 90.

It has also been seen that the aforedescribed poppet body includes a circular skirt at least in part encircling a helical spring and provided with a plurality of symmetrically arranged inclined bores arranged in concentric array relative to the associated skirt.

There will now be obvious to those skilled in the art many modifications and variations of the constructions and apparatus set forth hereinabove. These modifications and variations will not depart from the scope of the invention if defined by the following claims.

What is claimed is:

1. Apparatus comprising a pressurized cable including internal conductors and a cable cover surrounding said conductors and adapted to withstand an internal pneumatic pressure, a pressure tight case, electronic circuitry in said case, said conductors including a section extending in sealed relationship out of said cable cover into the case and being connected to said circuitry, and valve means bypassing said section and connecting said pressurized cable to said case and including both a manual control means to isolate said case from said cable and a check valve means to limit the flow of a pressure medium from said case back into said cable.

2. Apparatus as claimed in claim 1 wherein said valve means includes a valve body provided with a bore extending therethrough, said bore having an enlarged chamber at one end thereof, a member provided with a bore, and fixed in said chamber to confine an inner chamber therein, said bores and inner chamber cooperatively forming a flow passage, 21 poppet in said inner chamber, said member including a seat protruding towards said poppet and encircling the bore in said member, said poppet including a poppet body and a poppet inset in said poppet body, said inset having a hardness of 50-80 on the Durometer A scale and being adapted to engage said seat, a spring in said inner chamber urging said poppet and thereby said inset against said-seat whereby to cut off flow through said flow passage, and cutoff means in said valve body to cut off flow in the bore in said valve body.

3. Apparatus as claimed in claim 2 wherein said cutoff means includes a rotatable part rotatable about an axis perpendicular to the bore in said valve body and having a diametral bore selectively alignable with the bore in said valve body.

4. Apparatus as claimed in claim 3 wherein said valve body is of metal and said rotatable part is a fluorocarbon compound.

5. Apparatus as claimed in claim 4 comprising an indicator external of said valve body and connected to said rotatable part.

6. Apparatus as claimed in claim 5 comprising a pin extending through said valve body and into said member to lock the latter to said valve body and a retaining ring to hold said rotatable part in said valve body, said valve body being of brass or stainless steel, said pin and ring being of stainless steel.

7. Apparatus as claimed in claim 2 wherein said poppet body includes a circular skirt at least in part encir-. cling said spring and is provided with a plurality of symmetrically arranged inclined bores arranged in concentric array relative to said skirt.

8. Apparatus as claimed in claim 2 wherein said valve body is of metal, comprising a primer coating of epoxypolyamide on said valve body and a coating of polyurethane on said primer coating.

9. Apparatus as claimed in claim 2 wherein said inset is of to fluoroelastomer.

10. Apparatus as claimed in claim 2 wherein said circuitry is a telephone repeater circuit.

11. Apparatus as claimed in claim 2 wherein said inset is of fluoroelastomer and has a hardness of -80 on the Durometer A scale.

12. Apparatus as claimed in claim 11 wherein said seat is a circular rim with a thickness in radial direction of 0.005 0.010 of an inch.

Claims

2. Apparatus as claimed in claim 1 wherein said valve means includes a valve body provided with a bore extending therethrough, said bore having an enlarged chamber at one end thereof, a member provided with a bore, and fixed in said chamber to confine an inner chamber therein, said bores and inner chamber cooperatively forming a flow passage, a poppet in said inner chamber, said member including a seat protruding towards said poppet and encircling the bore in said member, said poppet including a poppet body and a poppet inset in said poppet body, said inset having a hardness of 50-80 on the Durometer A scale and being adapted to engage said seat, a spring in said inner chamber urging said poppet and thereby said inset against said seat whereby to cut off flow through said flow passage, and cutoff means in said valve body to cut off flow in the bore in said valve body.

7. Apparatus as claimed in claim 2 wherein said poppet body includes a circular skirt at least in part encircling said spring and is provided with a plurality of symmetrically arranged inclined bores arranged in concentric array relative to said skirt.

9. Apparatus as claimed in claim 2 wherein said inset is of to fluoroelastomer.

11. Apparatus as claimed in claim 2 wherein said inset is of fluoroelastomer and has a hardness of 70-80 on the Durometer A scale.

12. Apparatus as claimed in claim 11 wherein said seat is a circular rim with a thickness in radial direction of 0.005 -0.010 of an inch.