FR2571846A1 - MECHANISM FOR DETECTING A FLOW IN A CONDUIT OF AN INNER DIAMETER UP TO 7.5 CM - Google Patents

Abstract

THE INVENTION CONCERNS A MECHANISM FOR DETECTION OF THE FLOW OF A FLUID IN A DUCT. IT INCLUDES A SADDLE 12 MADE OF PLASTIC MATERIAL AND FIXED ON A DUCT 16, OVER AN OPENING 14 OF THE LATTER, AND A FLOW DETECTION DEVICE 34 WHICH INCLUDES A REACTION ELEMENT 36 AND A REACTION ELEMENT 38. OPERATION, ARTICULATED WITH THEM. FIELD OF APPLICATION: DETECTION OF FLUID FLOW, ESPECIALLY CORROSIVE FLUIDS, IN DUCTS, ETC.

Description

The invention relates to a mechanism for detecting a flow in a

  fluid transport conduit, which mechanism comprises, in general, a saddle made of plastic material and adapted to be attached to the conduit, in leak-proof superposition to an opening of the conduit, and flow detection means adapted for are inserted into the conduit and movable in response to fluid flow therein, the detecting means including a reaction member which enters the seat. The invention relates to a flow detection mechanism, and more particularly to a flow detection mechanism that can be used for controlling

  other mechanisms such as a switch. -

  Flow detection mechanisms of the type indicated are suitable for many and various applications for detecting and controlling a flow in a fluid transport apparatus, as well as for controlling an associated structure in response to the presence or absence of a flow of fluid. Many of these mechanisms, currently available, detect a fluid flow by moving a pallet or other similar detector disposed in a fluid transport conduit. A physical movement of the detector results, either directly from the action of the flow of a fluid on this detector, or from the use of a structure such as orifices, fins or

  turbines placed in the duct and giving rise to a difference

  pressure causing the detector to move.

  This physical movement must then be transmitted outside the conduit to manipulate a switch, usually electrical, to indicate the presence

of a flow.

  A typical example of such detection mechanisms

  flow is described in the US patent

2 -7 1846

  No. 4,454,768. A characteristic of the

  The devices described in this patent are that the body or saddle carrying the actuating means is made of a metal such as aluminum or copper. Although these devices give for most satisfaction, they pose corrosion problems. In particular, after a prolonged period of time, electrolysis takes place and there is corrosion of the saddle. This problem is particularly serious because of the enormous pressures

  of fluid that can be generated in the circuit.

  These pressures can cause catastrophic failure.

  trophic mechanism of detection.

  The object of the invention is therefore to propose a flow detection mechanism which is resistant to the effects

  corrosive of the fluid to be detected. Another object of the invention

  is a mechanism of this type in which the

  Saddle is made of plastic material.

  The invention will be described in more detail with reference to the accompanying drawing by way of non-limiting example and in which: - Figure 1 is an elevation, in partial section, of the flow detection mechanism according to the invention associated with a led by which a fluid can flow; and - Figure 2 is a view similar to that of Figure 1, but showing from another angle the

mechanism associated with a conduit.

  The figures show a flow detection mechanism 10 which is housed in a body or saddle 12 designed to be connected to an opening 14 of a duct 16 by means of sealing gaskets 18, in a manner well known in the art. the technique. The saddle 12 consists of a cup-shaped element 20 having an open end 22 and a base 24 in which an opening 26 is formed. The opening 22 is closed by a

257 1846

  elastic member 28 which forms a seal with the body. A rigid plate 30 holds the seal 28 and

a support plate 32 in position.

  A flow sensing device 34 responds to a flow of fluid in the conduit 16. The sensing device 34 includes a reaction member 36 and an actuating member 38. The reaction element 36 comprises a rod 40 and a rigid arm 42 which is fixed to the rod. The latter passes through openings 44 of the plate 30 and 46 of the support plate 32 and its sealing is provided by the elastic element 28. The rod 40 is designed so as to be able to pivot about a point 48 thanks to the articulation of the free ends 42 'and 42 "of the arm 42 in grooves

of the support plate 32.

  The actuating element 38 comprises a pallet 50 which is mounted in the duct 16 and which can pivot on an axis 52 by means of helicoidal springs 54 and 56. More particularly, the free ends 54 'and 56' of the springs are connected to the pallet 50. The reaction element and the actuating element are articulated to each other by the other ends 54 "and 56" of the springs which are connected to or engaged with a

  sleeve 58 carried by the arm 42 of the reaction element.

  As shown, the axis 52 is kept fixed

  in alignment with the opening 26 with cylindrical notches 27 and 29 to substantially prevent entry

  flowing fluid in the body.

  With particular reference to FIG. 2, in which the flow direction of the fluid is indicated by an arrow, the blade 50 is subjected to a force rotating it in the opposite direction to that of the needles on the axis. 52, which pivots the arm 42 and thus the rod 40 in the direction of clockwise to close a switch 60. When the flow of fluid in the conduit stops, no force acts on the pallet and a spring 62 rotates the rod 40 counterclockwise to open the switch 60 and return the pallet 50 to its "rest" position 64 through the coil springs 54. and 56. The fact that the actuating element and the reaction element both have a point of articulation requires less force to open the

switch 60.

  According to the invention, the saddle 12 is made of plastic. The latter must be able to withstand pressures of the order of 6000 kPa for ducts with an inside diameter of up to 7.5 cm. It must therefore be very resistant and hard. But, most importantly, it must be substantially impermeable to fluids such as water or oil for extended periods of time (20-30 years). A plastic that has proved suitable is a "nylon" reinforced with glass fibers, marketed by Dupont under the name "Zytel 90G301". This material was subjected to water at a temperature of about 85 C and a pressure of 1225 kPa for a period of 6 months, by Underwriters

  Laboratory. The material proved almost imper-

melt with hot water.

  It goes without saying that many modifications can be made to the mechanism described and represented

  without departing from the scope of the invention.

Claims (3)

  1. Mechanism for detecting a flow in a fluid transport conduit (16) having an inside diameter of up to 7.5 cm, characterized in that it comprises a saddle (12) made of plastic material and designed to be fixed to the conduit, in sealed superposition to an opening (14) of the conduit, and a sensing device (34) adapted to be inserted into the conduit and moved in response to fluid flow in that conduit, which sensing device includes an element   (36) reaction that enters the saddle.   2. Mechanism according to claim 1, characterized   characterized in that the saddle is made of a material   glass-reinforced plastic, of the "nylon" type.   3. Mechanism according to claim 2, characterized   the seat is made of "Zytel 90G301".