WO2013035119A1

WO2013035119A1 - Valve equipped with plastic spring

Info

Publication number: WO2013035119A1
Application number: PCT/IT2012/000267
Authority: WO
Inventors: Nicola Carbone
Original assignee: Etatron D.S. Spa
Priority date: 2011-09-08
Filing date: 2012-09-04
Publication date: 2013-03-14
Also published as: ITRM20110140U1

Abstract

A one-way injection valve (B) for metering pumps (F), characterized in that it comprises a thrust spring (M) made of plastic material highly resistant to chemical and mechanical attack, such as for example PVDF, appropriately installed in contrast with a ball (S) that bears upon a purposely provided O-ring towards which it is pressed by the spring (M) itself.

Description

VALVE EQUIPPED WITH PLASTIC SPRING

*****

The present innovation substantially relates to the sector of accessories for electromechanically driven metering pumps for metering liquids.

Said metering pumps are used for metering additives of various nature. They are devices that find widespread use in numerous applications, both industrial and domestic, such as for example:

Treatment of drinking water

Public and private swimming pools

Car-washes

Laundries

Galvanic-treatment plants

'Chemical industries

Cooling towers

Fertilization-irrigation

Agricultural and foodstuff industry

etc .

These apparatuses come provided with accessories, such as for example the injection valve.

More specifically, the subject of the present innovation is substantially the application in a oneway injection valve of a helical compression spring, obtained by means of an process of injection moulding of thermoplastic material. In the case in point polyvinylidene fluoride (PVDF) is used, commercially known as KYNAR, SOLEF, DYNEON, HYLAR, SYGEF, etc.

This material is known and widely used in the sector of metering pumps for its excellent resistance to chemical .aggression, especially in regard to strong acids in a wide range of temperatures (-40 °C to +150°C), with excellent characteristics of strength.

A better understanding of the utility model will be obtained from the ensuing detailed description and with reference to the attached plates of drawings, which illustrate, merely by way of non-limiting example, a preferred embodiment and application of the invention.

Figure 1 represents a typical scheme for installing an electromechanical metering pump F with accessories, where designated by B is the one-way injection valve forming the subject of the present innovation .

Figure 2 represents an example of a PVDF spring.

Figure 3 is an overall view of the one-way injection valve.

Figure 4 is a cross-sectional view of the one-way injection valve.

Figures 5 and 6, regarding a variant of the spring equipped with contrast elements or anti-packing shims, show said variant in free configuration and compressed configuration, respectively.

In the application described, the function of the spring M is to create a force of contrast against opening of the clapet in the one-way injection valve B; this is normally obtained by means of a ball S. This force, in the sphere of application of the non-return valve, results in a pressure on the delivery line of the pump. Normally, the delivery of electromechanical metering pumps is installed on the piping A of the plant to be .treated by means of the injection valve B, the function of which is to prevent return of the fluid into the metering pump itself. Another important function performed by the injection valve B is to supply a back pressure on the delivery of the metering pump F, and this circumstance is obtained by using the spring M, which, by pressing on the ball S, generates precisely this thrust.

Figures 5 and 6 illustrate a variant Ml of said spring M. Said variant is particularly indicated for eliminating the problems of packing of the spring Ml made of plastic material as compared to normal metal springs. Advantageously, said variant can be easily obtained with the process of production by thermoplastic moulding.

With reference to the geometry in question, purely by way of example, appearing in the ensuing table are the values of force that the spring develops as the deflection increases. Likewise listed are the respective values of resulting pressure on the basis of the diameter of the contrast ball.

Table - Values of force and pressure

Characteristic graph of the PVDF spring

The advantages deriving from application of the particular spring on the bottom injection valve accessory for electromechanical metering pumps can thus be summed up as follows: -

- the spring elastic element made of corrosion- resistant plastic material represents an undoubted advantage in the use of this device in the metering of chemically aggressive fluids, such as for example strong acids;

- the device equipped with the PVDF spring has a characteristic of resistance to corrosion that is practically homogeneous, because it is made up of items obtained from the same raw material;

- through the use of PVDF springs it is possible to avoid the use, once again in the context of metering of corrosive fluids, of very costly metal alloys, such as for example nickel alloys (HASTELLOY, MONEL, INCONEL, etc.);

- the spring that equips the injection valve is produced by means of a process of thermoplastic moulding, which is very advantageous from the economic standpoint and is suited to developing high production volumes;

precisely by virtue of the fact that the spring is obtained by means of moulding it is possible to obtain, once again for the spring element, embodiments with helix of variable, instead of constant, pitch, to differentiate both the characteristic curve and the geometry;

deflection of the spring may be limited, once again thanks to the moulding technology, by providing different embodiments, such as for example ones that are, in plan view, oval, square, polygonal, etc.

List of main parts illustrated in the figures:

A. Piping , H. Bottom filter

B. Injection valve I . Level probe

C. Back-pressure valve M. PVDF spring

D. Manometer Ml. Spring with contrast

E . Relief valve elements

F. Metering pump S. Ball

G. Tank

Claims

1. A one-way injection valve (B) for metering pumps (F) , characterized in that it comprises a thrust spring (M) made of plastic material highly resistant to chemical and mechanical attack, such as for example PVDF, appropriately installed in contrast with a ball (S) that bears upon a purposely provided 0-ring towards which it is pressed by the spring (M) itself.

2. The one-way injection valve (B) according to Claim 1, characterized in that said spring (M) is coaxial with the ball (S) , wherein said spring (M) is installed in such a way that its direction of thrust is opposite to the flow of the fluid to oppose its passage into the valve itself.

3. The one-way injection valve (B) according to Claim 1 or Claim 2, characterized in that said spring

(M) is set coaxially with respect to the valve and to the direction of flow of the fluid that traverses the valve (B) itself.

4. The one-way injection valve (B) according to any one of the preceding claims, characterized in that said spring (Ml) is equipped with contrast elements or anti-packing shims.

5. The one-way injection valve (B) according to any one of the preceding claims, characterized in that said spring (M) has an oval, or square, or polygonal shape in top plan view.

6. The one-way injection valve (B) according to any one of the preceding claims, characterized in that said spring (M) is made with a constant-pitch or variable-pitch helix in order to vary as required its characteristics of elastic response with respect traditional helical spring.