CH364392A - Backflow preventer for fluid line - Google Patents

Description

Non-return device for a fluid line The present invention relates to a non-return device for a fluid line allowing the passage of fluid in one direction only. Such backflow preventers are widely used in multiple installations. These devices generally comprise a seat on which a ball rests under the action of its own weight. For one direction of flow of the fluid, the ball is lifted by the first fluid stream, while for the other direction of flow this ball is applied to its seat by the first fluid stream. This type of device generally works satisfactorily when the pressures causing the fluid to flow in one direction or the other are relatively high (0.5 atm and more). On the other hand, when the pressure tending to cause the fluid to flow in the non-desired direction is low, the ball is generally not applied strongly enough to its seat to oppose any flow of the fluid through the pipe.

The present invention tends to remedy this drawback by the fact that the non-return device comprises on the one hand a first piece forming a seat provided with two openings arranged on either side of a plane of sym6try and on the other hand a second piece in a elastically deformable material forming a valve, tight by its peripheral edge on the seat, and which has an incision made symmetrically with respect to said plane of symmetry, in order to form two lips, applied to said seat by its own elasticity of the material of this second piece.

The appended drawing illustrates schematically and by way of example one form of execution of the non-return device.

fig. 1 is a view partially in section of a pipe section provided with the non-return device. fig. 2 is a plan view of the seat. fig. 3 is a plan view of the valve.

fig. 4 is a sectional view of the anti-return device of fig 1.

According to the appended first drawing, the non-return device comprises a) a first part 1 constituting a seat of oblong shape and presenting two openings 2 arranged on either side of a plane of symmetry a; b) a second piece 3 made of an elastically deformable material, which has, in plan view, the same peripheral contour as the first piece 1. An RTI ID="0001.0272" WI="12" HE="4" LX= "1381" LY="1717"> incision 4, 5 is made in this part 3 symmetrically to its longitudinal plane of symmetry so as to form two lips 6.

Piece 3 is tight or glued in c (fig. 4) over the entire length of its peripheral edge on the peripheral edge of piece 1 and the inherent elasticity of the material tends to maintain its lips 6 in the same plane and applied on side 7 of part 1.

The operation of the device described is as follows: When the latter is arranged inside a pipe as represented by FIG. 1, the two p ikes 1 and 3 being tightened one on the other by their peripheral edges between shoulders 8 of a connection tightened by means of a collar 9, the proper elasticity of the material of the second part 3 forming a valve, tends to maintain the lips 6 on the face of the seat 1 and therefore to close the openings 2. It follows that the device opposes a flow of the fluid (gas or liquid) to through pipe d in the opposite direction to arrow f. Furthermore, any pressure from the fluid tending to cause it to circulate in the opposite direction to the arrow f applies the lips 6 to the face of the seat so that the greater this pressure, the more perfect the seal.

On the other hand, a pressure tending to circulate the fluid in the direction of the arrow f causes an elastic deformation of the part 3, the lips 6 of which are then raised from the face of the seat, as represented by FIG. 1. Fluid can now flow freely through line d in the direction of arrow f.

The tests carried out have shown that the seat and the valve 3 can advantageously be cut from sheets of plastic material (synthetic resin), which makes it possible to produce not only a very sensitive non-return device (the operating sensitivity being solely a function of the thickness of the part 3 and the elasticity or flexibility of the material) and perfectly sealed, but still at an extremely low cost price since all the constituent parts of this device are obtained by simple cutting on the press.

It goes without saying that the dimensions of the openings are chosen according to the flow rate required and the pressure in the opposite direction of the arrow f that the non-return device must be able to withstand.

The shape of the incision 4, 5 is chosen according to the arrangement and the shape of the openings 2 but excellent slow results have been obtained using the incision shown in the drawing and which comprises a wavy line 4 separating the two lips and a line 5 in an arc of a circle at each end of this line 4.

Claims (2)

Non-return device for a fluid pipe allowing the passage of the fluid in one direction only, characterized in that it comprises on the one hand a first part forming a seat provided with two openings arranged on either side of a plane of symmetry and, on the other hand, a second part made of an elastically deformable material and forming a valve, tightened by its peripheral edge on the seat, and which has an incision made symmetrically with respect to said plane of symmetry, in order to form two lips, applied to said seat by the inherent elasticity of the material of this second part. 1. Device according to claim, characterized in that the seat and the valve have an oblong shape in plan, the seat having two elongated openings, while the valve has an incision formed by a wavy line and 'a line in the shape of an arc of a circle at each end of this wavy line. 2. Device according to claim and sub-claim 1, characterized in that the seat and the valve each consist of a piece cut from a sheet of plastic material, the seat being of greater thickness than the valve.