VALVE SYSTEM FOR ATEX ENVIRONMENT

Abstract

A valve system (1) comprising a valve having a valve stem (50), a valve body (20) and a stuffing box (30) assembled to the valve body, the valve system comprising a washer (60) in contact with the stem (50) and the stuffing box (30), the washer (60) comprising an electrically conductive material.

Claims

1. A valve system comprising: a valve having a valve stem, a valve body and a stuffing box assembled to the valve body, the valve system comprising a washer in contact with the stem and the stuffing box, the washer comprising an electrically conductive material.

2. The valve system of claim 1, the washer comprising an annular portion and at least one flexible leg extending axially from the annular portion.

3. The valve system of claim 1, the flexible leg(s) extending axially from an inner periphery of the annular portion.

4. The valve system of claim 3, the washer comprising four flexible legs equidistantly arranged on the inner periphery of the annular portion.

5. The valve system of claim 2, the annular portion and the flexible legs being integrally formed.

6. The valve system of claim 2, the flexible legs being in contact with the valve stem and the annular portion being in contact with the stuffing box.

7. The valve system of claim 2, the flexible legs having raised edges not in contact with the valve stem.

8. The valve system of claim 1, the stuffing box comprising a stuffing box body housing a stuffing box spring, the annular portion being sandwiched, at least partially, between an internal surface of the stuffing box body and the stuffing box spring.

9. The valve system of claim 3, the inner periphery of the annular portion having a diameter larger than a diameter of the valve stem in a potion thereof received in the stuffing box.

10. The valve system of claim 1, the valve stem comprising an electrically conductive material.

11. The valve system of claim 1, comprising a plastic stopper at a first end of the valve stem and a plastic material disc connected to a second end of the valve stem.

12. The valve system of claim 1, comprising a top box housing a plastic piston, the valve stem extending through the piston.

13. The valve system of claim 1, an external surface of the valve stem defining a shoulder, the valve system comprising a plastic washer arranged between the shoulder and a bottom of the piston.

14. A method for grounding the valve system of claim 1, in which the valve stem is grounded only via the washer.

15. A method for manufacturing a valve system adapted for ATEX environment, comprising arranging an electrically conductive washer around the valve stem so as to obtain the valve system according to claim 1.

16. An ATEX environment comprising: at least one valve system of claim 1.

17. The valve system of claim 5, wherein the annular portion and the flexible legs comprising bronze, brass or copper beryllium alloy.

18. The valve system of claim 7, wherein the flexible legs are in punctual contact with the valve system.

Description

DETAILED DESCRIPTION OF THE ILLUSTRATED FIGURES

[0028] FIG. 1 is a schematic longitudinal section of a valve system according to the invention;

[0029] FIG. 2 is an enlarged view of circled area II of FIG. 1;

[0030] FIG. 3 is a perspective view of an example of a washer according to the invention, and

[0031] FIG. 4 is a picture showing a longitudinal sectional view of the washer parallel to a longitudinal axis of the valve system.

[0032] A valve system 1 of the invention, as shown in FIG. 1, comprises a valve body 20 and a top box 10, which houses a plastic piston 14. A valve stem 50, made of an electrically conductive material, for example stainless steel, extends through the piston 14 and is fixed thereto. The valve stem is received at a first end in a plastic stopper 79 and extends by a second end into the valve body 20. The valve system comprises a plunger 40 comprising a PTFE disc connected to the second end of the valve stem 50. The disc 80 seals the valve body 20 in a closing state of the valve system.

[0033] The valve stem 50 comprise on an external surface a shoulder 56. A plastic washer 41 is arranged between the shoulder 56 and a bottom of the piston 14.

[0034] The valve system in the illustrated embodiment is a pressure operated valve and comprises two fluid inlet/outlet 44 in the top box 10. The stuffing box comprises a stuffing box body 31 housing a spring 70 and chevrons packings 35 pushed by the stuffing box spring 70. An internal surface of the stuffing box body defines a shoulder 34 facing the spring 70. The stuffing box body 31 comprises an electrically conductive material and is made for example of stainless steel.

[0035] As shown in FIG. 2, the valve system 1 further comprises a washer 60 in contact with both the valve stem 50 and the stuffing box 30. The washer 60 is made of an electrically conductive material, for example brass, bronze or copper beryllium alloy.

[0036] As shown in FIG. 3, the washer 60 comprises an annular portion 61 and four flexible legs 63 extending axially from an inner periphery 62 of the annular portion 62. The flexible legs 63 are regularly arranged around the longitudinal axis X of the valve system.

[0037] As shown in FIG. 2, the annular portion 61 is arranged between an axial end of the spring 70 and the shoulder 34 of the stuffing box body 31. The annular portion 61 is at least partially in contact with the shoulder 34. The flexible legs 63 are arranged between the valve stem 50 and the spring 70.

[0038] The flexible legs 63 bend radially inwards, as illustrated in FIG. 4. The flexible legs have a raised edge 64 that is not in contact with the valve stem 50. The flexible legs 63 are for example in contact with the valve stem 50 only by contact points.

[0039] The diameter r of the inner periphery 62 of the annular portion 61 is larger than a diameter R of the valve stem 50 in a portion of the latter received in the stuffing box 30.

[0040] The flexible legs may have a width w between 2 mm and 5 mm.

[0041] The flexible legs may have a length/between 5 mm and 15 mm.

[0042] The washer may be produced, for example by punching a sheet of metal, in order to form a piece of metal comprising an annular portion and portions that extend radially from the inner periphery of the annular portion before being bent. The radially extending portions can be bent form the flexible legs. The radially extending portions can be bent by an angle of between 60 to 80 in order to insure contact with the valve stem 50.

[0043] The orientation of the flexible legs 63 ensures contact with the valve stem 50 with reduced friction between the flexible legs 63 and the valve stem 50.

[0044] The invention is not limited to any particular top box, and various changes may be brought to the top box without departing from the scope of the invention.

[0045] The number of flexible legs 63 may be else than four.