DE2429448A1 - DIAPHRAGM SEALED VALVE - Google Patents

Description

Diaphragm sealed valve

The invention relates to a diaphragm-sealed valve, in particular for aggressive media and steam, with a laminated, multi-layered one PTFE membrane-formed plunger leadthrough of the Valve actuation.

In the case of valves for aggressive media, the use of corrosion-resistant Materials required as material for valve housings, valve closing bodies and sealing elements; is in particular The use of PTFE is advantageous because it has the highest chemical resistance compared to other plastics in question against all aggressive media of interest in practical application.

There are already known membrane valves whose valve space is used as an actuator is sealed by a PTFE-coated elastomeric membrane or by a single-layer homogeneous PTFE membrane. at the elastomeric membrane with a thin PTFE coating diffuses the aggressive medium due to the relative high permeability of the PTFE up to the elastomer membrane and chemically attacks it. The ones with a stronger PTFE coating provided elastomeric membranes or the single-layer PTFE membranes of sufficient layer thickness have due to the non-elastomeric Behavior of the PTFE on only a low flexibility and cause a relatively high expenditure of actuating energy for the valve actuation. Because of these disadvantages are currently found in Valves for aggressive media, preferably elastic plastics use as membrane materials. These elastomer materials do not have universal resistance to aggressive media, valve equipped with it cannot be used for all media of interest. It comes about, especially with

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Mixed liquids, the concentration and composition of which are not exactly known, are often used against äaa The flow medium of the valve has only limited resistance to membrane materials; the membranes then only have a short service life and the valves are more susceptible to failure marked.

The invention is based on the object of creating a valve its PTFE membrane seal compared to the well-known PTFE meme branch versions a higher flexibility (lower spring stiffness and higher freedom of movement) and higher pressure resistance and corresponds in its mechanical performance to the membranes made of elastomeric materials.

This object is achieved according to the invention in that the The membrane sealing the valve housing and, in the embodiment of the membrane drive, also the membrane of the membrane drive consists of a number of PTFE foils adapted to the required pressure range, either on their inner edges connected to one another in a pressure-tight manner by sintering and bracing and preferably sintered and braced at their outer edges or are only tensioned or lead radial ventilation openings or with the exception of the film on the pressure side with a Perforations are provided or are connected to one another in a pressure-tight manner at their inner edges by bracing and on their outer edges are tensioned or lead radial ventilation openings or with the exception of the film on the pressure side are provided with a perforation and are provided on the outer and inner edge of the membrane for the reception of centrally placed, Pre-tensioning rings preferably designed as O-rings have annular recesses.

Further embodiments of the invention emerge from the subclaims.

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The advantages achieved by the invention are in particular / that the laminated PTFE membrane on the one hand in all aggressive media of interest can be used, on the other hand a higher flexibility and compressive strength than the previously known single-layer or PTFE made of PTFE coated membrane designs made of elastomeric materials having.

Embodiments of the invention are shown in the drawing and are described in more detail below:

Show it

FIG. 1 shows a longitudinal section of the subject matter of the invention in

one of the possible diaphragm valve designs

Figure 2 in longitudinal section an embodiment of the laminated

PTFE membrane

Figure 3 shows the longitudinal section of an embodiment with clamped Support washers

Figure 4 in longitudinal section another embodiment of the mem-

fuel valves

Figure 5a shows a longitudinal section of the annular recess and the radial ventilation openings of the laminated PTFE membrane

FIG. 5b shows a plan view of the external clamping of the membrane leading to the radial ventilation openings

FIG. 6 a shows a longitudinal section of the perforated one i & mellated PTFE membrane

FIG. 6 b shows a plan view of the one provided with a perforation laminated PTFE membrane

The InventionGettötatiä according to Figure 1 relates to a diaphragm valve with pneumatic actuation, which in the unpressurized state of the pressure chamber 1 of the actuator, the open valve position, at Pressurization of the actuator drives the closed valve position has, whereby the pretensioned return spring 2 is the open

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position of the valve when the actuator is depressurized. The laminated PTFE membrane 3 serves at the same time as a valve sealing membrane and as a pneumatic or hydraulic control membrane. The membrane 3 is clamped between the lower valve part 4 and the upper valve part 5 via a screw connection not shown in the figure, the space 1 between the laminated PTFE membrane 3 and the upper valve part 5 forming the pressure chamber of the actuator. The valve plate 6 and the upper diaphragm clamping ring 7 are used as a support plate for the diaphragm

3 trained. The internal clamping of the membrane 3 between the two Support plate 6, 7 takes place through a clamping sleeve 8, which is over the thread of the valve stem 9, the clamping parts G, 7 presses together. The valve stem 9 is over the clamping sleeve 8 in an intermediate valve lower part

4 and upper valve part 5 clamped guide part 10 out and takes over the guidance of the valve disk 6. The return spring 2 of the valve becomes preloaded between the guide part 10 and a lug 11 turned on the clamping sleeve 8, the pressure equalization between the space 1 below the upper valve part 5 and the space 12 between membrane 3 and guide part 10 is through several circular holes in the Guide part 10 guaranteed.

As FIG. 2 shows, the multilayer, circular PTFE membrane 3 has a central bore 14 for the tappet lead-through and fastening. The annular recesses 15, 16 of circular cross-section serve to accommodate clamping rings 17, Γ8, which are preferably designed as O-rings. The membrane can have two or more layers , the number of PTFE foils 19 a .. d and their thickness being determined by pressure and actuating forces in adaptation to the respective membrane stresses. In the exemplary embodiment of the invention according to FIG. 2, the membrane foils 19 a ... d are held together by circular sintered seams 20, 21 on the inner and outer diameter of the membrane and the gaps between the foils are sealed off from the outside in a pressure-tight manner.

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In the embodiment according to FIG. 3, support disks 45/46 , preferably made of PTFE, are clamped between the support members 7 and the membrane 3 for better support of the membrane at high nominal pressures of the valve Manual training covers the annular gaps between the inner diaphragm support plates Π, 7 and the valve valves 4, 10 supporting the diaphragm on their outer edge and enable the diaphragm to be subjected to higher pressures.

In the valve design according to FIG. 4, the housing lower part 22, the valve disk 23, are the. Laminated PTFK sealing membrane identical to the corresponding parts in FIG. 1; the valve drive consists of, for example, a pneumatically or hydraulically actuated actuator with spring return. The lamellar Ι'ΊΊΤ.-sealing membrane 24 is clamped between the lower housing part 22 and a middle housing 25 and the control membrane is located between the middle. Housing 2Γ, and the upper housing part 2 ", the sealing membrane 24 and operating membrane 26 form a structural unit with the valve plate 33, support plate 30, valve stem 29, the middle housing 25 and the support plate 28 of the control membrane Housing 25 is sealed and the space 35 above the sealing membrane 24 is vented into the atmosphere via the bore 36 in the middle housing 25. The clamping of the membranes 24 * 26 at their inner diameters takes place via separate screw connections of the valve stem M with the valve tappet 31 and the valve tappet 31 . with the support "plate 30 of the stiffener em bran © 26 by a cap nut 32; * Leres thereby ensures 24,26 'ensure the interchangeability © independently of both diaphragms ,. C _f e Hau se Sf shell with center housing 25 and housing nütt 2.5; with G-housing lower part 22 are independent

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dependent on one another by screw connections not shown here tied together. This allows the sealing membrane to be replaced

24 without separating the upper housing part 27 from the middle housing

25 as well as the replacement of the operating diaphragm 26 without separating the lower housing part 22 from the middle housing 25.

In a further embodiment of the laminated PTFE membrane shown in FIGS. 5 a, b, a radial venting of the film spaces is achieved by film incisions 37 extending over the outer clamping ring 15 held in annular depressions; this prevents the membrane from inflating as a result of diffusion or leakage flow from the valve space into the spaces between the foil.

In the embodiment of the laminated one shown in FIGS. 6 a, b PTFE membrane becomes a vent, the spaces between the foil by perforating the individual foils 38 a..c only exception the sealing film 39 on the pressure side is reached; this venting closes a swelling of the membrane as a result of a Diffusion flow from the valve chamber into the film spaces between the sealing membrane 24. The through the sealing membrane 24 diffusing medium is passed through the bore 36 of the middle housing 25 into the atmosphere.

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Claims (1)

2 * 29448 Protection claims Ij diaphragm-sealed valve, its valve housing, valve seat and valve head made of PTFE or other corrosion-resistant materials (metal, plastic) and its valve seat by an electromagnetic, electromotive drive, membrane drive, piston drive or by direct or pilot-operated Pressurization of the sealing membrane of the valve housing is actuated, characterized in that the The membrane 3, 24 sealing the valve housing 4, 22 and, in the embodiment of the membrane drive, also the membrane 26 of the diaphragm actuator from a number of PTFE foils adapted to the required pressure range Ii) a..d, 38 a..c, exists, which are connected to one another in a pressure-tight manner either at their inner edges by sintering and bracing, and at their outer edges are preferably sintered and braced or only braced and lead radial ventilation openings 37 or with the exception of the film 39 on the pressure side, are provided with a perforation or on their inner edges are connected to one another in a pressure-tight manner by bracing and are braced at their outer edges and have radial ventilation openings 37 lead or, with the exception of the film 39 on the pressure side, are provided with a perforation and on the outside and .inner edge of the membrane 3, 24, 26 for receiving centrally inserted pretensioning rings, preferably designed as O-rings 17, 18 have annular recesses 15, 16. 2, membrane-sealed valve according to claim 1, characterized in that one or more foils 19 a. .d, 38 a..c of the PTFE membrane 3, 24, 26, with the exception of the film 39 on the pressure side, are reinforced with a fabric insert made of glass fiber or plastic. -. _Λ _ _{Λ Λ} 509883/0798 -2-BATH ORIGINAL 3. Diaphragm-sealed valve according to claims 1 and 2, characterized in that the laminated PTFE membrane 3, 24, has a stronger sealing film 39 on the side of the application of pressure and the films above it have a smaller and / or have continuously decreasing film thickness. 4. Diaphragm-sealed valve according to claims 1-3, characterized in that the clamping parts 6, 7, 23,28,3Oder PTFE membrane at the same time designed as a membrane support plate and elastic, preferably between the support plate and membrane Supporting disks 45, 46 made of PTFE are clamped in, which form the annular gaps due to their bead-shaped edge formation Cover between the membrane backing plate and the external clamping of the PTFE membrane. 509883/0798 Blank page