FR2689607A1 - Automatic safety valve for industrial and domestic gas installations - has body having housing for blocking assembly which is mounted on return member in open position which blocks flow of gas when excessive flow of gas occurs - Google Patents

Abstract

The unit is made up of a body (9) containing a housing (12) for a shut off assembly (13). The assembly is provided with an elastic element (16) which normally holds the valve element (17) off its seat (15). When there is an excessive flow of gas in the direction (G) through the valve, a pressure drop is produced across the valve assembly which when reaching a predetermined level, closes the valve (17) onto its seat. The valve reopens when this pressure difference is removed. Use/Advantage - As an automatic safety valve for use in industrial and domestic gas installations where if there is a excessive downstream leak due to the rupture of a pipe the valve closes automatically to prevent the loss of gas which could cause a hazard.

Description

AUTOMATIC SAFETY DEVICE FOR INSTALLATIONS
INDUSTRIAL OR DOMESTIC GASES
The invention relates to an automatic safety device for industrial or domestic gas installations.

 Gas installations must be quickly isolated in the event of a leak in a pipe because the increase in the concentration of gas in the atmosphere quickly leads to asphyxiation of people or to an explosion causing significant material damage.

 For this purpose, there are known quick-closing taps called "fist" designed to allow instant gas shutdown in residential buildings and establishments receiving the public.

 The closing of these known taps is obtained by simply pressing a push button, but the reopening of this tap however requires the use of a special key by a person duly authorized for this purpose.

 These known valves thus have the disadvantage that closure and return to the open position is not obtained automatically without human intervention.

 The invention aims to overcome this drawback by creating an automatic safety device requiring no human intervention, able to instantly cut the flow as soon as this flow exceeds a predetermined value and able to return to its original position when the equality of upstream and downstream pressures is restored.

 The invention relates to an automatic safety device for industrial or domestic gas installations, comprising a body capable of being made inseparable from a gas pipe made of rigid material, characterized in that the body has a housing for a shutter assembly , said shutter assembly being provided with a retaining means in the open position so as to: move in the direction of flow of the gas in the event of a predetermined value of the gas flow rate being exceeded be kept in the closed position on an integral seat of the body by the force exerted by the relative pressure of the gas; and be returned to the open position by said retaining means in the absence of relative gas pressure.

 The device according to the invention makes it possible in particular to avoid accidents, insofar as the creation of a significant leak greater than the predetermined flow rate automatically causes the device to close and thus eliminates any risk of accident, suffocation or 'explosion.

According to other features of the invention
- the shutter assembly comprises a retaining means made at least partially of a material having a significant elasticity, of the elastomer type or the like, and a shutter valve capable of cooperating with the seat
- The retaining means comprises a ring, substantially toroidal, of shape adapted to the shape of a housing groove secured to the body and at least two arms joined together by a fixing ring;
- the shutter valve has a shape cooperating with that of the fixing ring, to be held by the fixing ring substantially along the axis of revolution of the substantially toroidal ring
- The retaining means comprises three arms of substantially rectangular cross section and having a substantially spherical curvature profile;
- the shutter valve has, on the side opposite to a surface having an aerodynamically shaped profile, a hollow shape, so as to reduce the mass of the shutter valve;
- The body is made inseparable from the pipe of rigid material by crushing a deformable ring engaged on an end of suitable shape, for example having grooves, of the rigid pipe so as to ensure the external sealing of the pipe
the crushing of the ring is obtained by means of a nut in two parts made integral 1 with one another by a securing means such as a shear pin
- the radially outer part of the nut is able to rotate freely after complete crushing of the ring and rupture of the securing means
- in the crushing position of the ring, the radially outer part of the nut has an overlapping shape of the radially inner part so as to prevent any introduction of a tool capable of operating the radially inner part
The invention will be better understood thanks to the description which will be given by way of nonlimiting example with regard to the appended drawings in which
Figure 1 schematically shows in section a device according to 1 invention, according to an assembly of two schematic half-views in radial section, joined, representing the device according to the invention in two different positions.

 FIG. 2 schematically represents a shutter assembly of the device according to the invention, according to an assembly of two schematic half-views in radial section joined against the lines marked Il-Il of FIG. 3.

 FIG. 3 represents a schematic view from above in the direction of the arrow III in FIG. 2.

 Figure 4 shows a top view of a retaining means of a device according to the invention.

 FIG. 5 represents a schematic sectional view along the line marked V-V in FIG. 4.

 FIG. 6 schematically represents a shutter valve of a device according to the invention according to an assembly of two joined schematic half-views, with a left schematic half-view in radial section.

 With reference to FIG. 1, a safety device according to the invention is shown on the left in a position A and on the right in a position B.

 The device according to the invention is made integral with a gas pipe made of rigid material, for example made of metal so as to be assembled therein inseparably, for example by welding, soldering, screwing, or the like.

 In the example shown, according to the invention, the device is assembled to a grooved butt 1 by means of a ring 2 made of elastomeric material, for example nitrile of insufficient hardness.

 The ring 2 is crushed by screwing a nut in two parts 3, 4 made integral by at least one shear pin 5, for example made of steel.

 The radially inner part 3 of the two-part nut has a flange 6 of diameter greater than the outside diameter of the end piece 1.

 In position A corresponding to the left half-view, the ring 2 engaged on the splined end 1 is in the free position, the nut in two parts 3 and 4 made integral is engaged by the thread 7 on the internal thread 8 of the body 9 of the device, preferably directly machined in the body 9 of the device according to the invention.

 In position B corresponding to the right half-view, the radially outer part is screwed using a tool resting on its periphery until the shear pins 5 break.

 In this position B, the ring 2 crushed by the support of the rim 6 in turn exerts a compression effect on the grooves of the end piece 1 which prevents any manual extraction of this butt while ensuring the external sealing of the pipe .

 In addition, after rupture of the shear pin (s) 5, it is no longer possible to dismantle the device according to the invention even with the help of a tool the radially outer part 4, then freely rotating around of the radially inner part 3, preferably has for this purpose an overlapping shape, so as to prevent any introduction of a tool capable of operating the radially inner part 3.

 In the example shown, the upper face 10 of the radially outer part 4 is substantially at the same level as the upper face 11 of the radially inner part 3.

 According to the invention, the device comprises a body 9 preferably made of metal, for example steel or brass.

 The body 9 is machined internally and externally to allow its connection to a pipeline or a gas installation.

 The body 9 includes a housing 12 for a shutter assembly 13 in one or more parts which will be described below.

 Preferably, the housing 12 is produced by machining an annular groove directly in the body 9, of a shape capable of retaining a substantially toroidal ring 14 secured to the shutter assembly 13.

 In position A, the shutter assembly is shown in the open position so that the gas, the direction of flow of which is represented by the arrow G and the corresponding broken lines, can circulate freely in the installation.

 In position B, the shutter assembly 13 is shown in the closed position and prevents the passage of any significant flow of gas, preferably prevents any leakage greater than 5 l / h (1.39 cm3 / s) of gas at a relative pressure. of 20mbar.

The operation of the device is as follows
below a predetermined flow value, for example of the order of 1.2 m3 / h (333cm3 / s), of gas at low pressure (about 20mbar relative), the gas speed is low and not exerted no significant force on the shutter assembly 13;
above this predetermined value, for example in the event of a rupture of a flexible pipe situated downstream of the device, the shutter assembly 13 moves in the direction of circulation G of the gas until it is pressed against its seat 15 integral with the body 9;
the shutter assembly 13 is then held in position on its seat 15 by the force exerted by the relative pressure of the gas on its outer surface;
if the gas supply is cut off, minimal gas leaks cause the gas pressure to drop until equilibrium with atmospheric pressure or the gas pressure prevailing on the side of the seat 15 opposite the shutter assembly 13; at pressure equilibrium, the shutter assembly 13 which is according to the invention provided with a retaining means in the open position is recalled to the open position by said retaining means in a predetermined time interval, preferably less than one minute.

 Referring to Figure 2, the shutter assembly 13 is preferably made in two parts: a retaining means 16 capable of exerting an elastic return force towards the open position and a shutter valve 17 capable of cooperating with its seat 15 secured to the body 9 of the device according to the invention.

 The retaining means 16, preferably produced by molding an elastomeric material, comprises a substantially toroidal ring 14 and at least two arms 18 (three arms in the example shown) joined together substantially at the axis of revolution of the ring 14, by a fixing ring 19 and fixed at their ends opposite to the ring 14.

 The three arms 18 are arranged substantially at 1200 and have equal lengths, so as to center the fixing ring 19 during the movements resulting from the opening or closing of the shutter assembly 13.

 The fixing ring 19 has a shape and a diameter suitable for holding the shutter valve 17 along the axis of revolution of the ring 14: the shutter valve 17 has, for this purpose, a cooperating shape, advantageously an annular groove 21.

 Referring to Figures 4 and 5, where the elements identified by numbers identical to those of Figures 1 to 3 denote identical or similar elements, the arms 18 disposed at 1204 have a substantially rectangular cross section and a substantially spherical curvature profile.

 The height of the ring 19 is substantially greater than the thickness of the arms 18, preferably greater than one and a half times the thickness of the arms, so that the ring 19 is substantially non-deformable during movement and arm deformation 18.

 During the movement of the ring 19, the arms 18 of elastomeric material having a high elasticity, tend to return CL to their equilibrium position thereby causing the opening of the shutter assembly 13.

 The substantially toroidal ring 14 advantageously has an inner contour 14a, substantially cylindrical of revolution, so as to minimize the pressure drop due to the shutter assembly 13 for example along circulation lines substantially parallel to the generatrices of the cylinder 14a.

 Referring to Figure 6, the shutter valve 17 has a substantially cylindrical upper portion 22 of diameter corresponding to the inner diameter of the ring 19, an enlarged portion 23 substantially conical adapted to widen the ring 19 during insertion by elastic deformation of the fixing ring 19 around the annular groove 21.

 The lower part of the groove 21 has a rim 24 of diameter corresponding to or slightly greater than the outside diameter of the ring 19.

 The rim 24 is limited by a substantially cylindrical shape 25, to which is connected a surface 26 having an aerodynamically shaped profile adapted to the flow of gas.

 In the example shown, the form 26 is substantially conical and is rounded in connection with a substantially cylindrical surface 27.

 The diameter of the substantially cylindrical surface 27 is less than the diameter of the substantially cylindrical contour 14a of revolution, so as to minimize the pressure losses while preventing any jamming of the shutter valve 17 inside the ring 14.

 The shutter valve 17 advantageously has, on the side opposite the surface 26, a hollow shape 28 so as to reduce the mass of the shutter valve 17 and the dynamic fluttering effects resulting from the application of too great a mass to elastic arms 18 of small cross section.

 The shutter valve 17 preferably has an annular bearing surface 29 of reduced width capable of being applied to the seat 15 to reduce the gas flow to values of less than 5 l / h (1.39cm3 / s) .

 The invention described with reference to a particular embodiment is in no way limited thereto, but on the contrary includes any modification of form and variant of execution within the scope and in the spirit of the invention.

 The shutter valve 17 has a shape substantially of revolution and is maintained substantially along the axis of symmetry of the device described. A shutter valve can, according to the invention, be articulated directly on a substantially O-ring 14 by a single arm.

 In this case, the retaining means is separate from the O-ring 14 and can comprise an elastic means, of the spring type, for example a conical spring working either in elongation or in compression.

Claims (10)

 1. Automatic safety device for industrial or domestic gas installations, comprising a body (9) capable of being made inseparable from a gas pipe made of rigid material, characterized in that the body (9) has a housing (12) for a shutter assembly (13), said shutter assembly (13) being provided with a retaining means (16) in the open position so as to: move in the direction of flow (G) of the gas in the event of exceeding a predetermined value of the gas flow; be kept in the closed position on a seat (15) secured to the body (9) by the force exerted by the relative pressure of the gas, and be returned to the open position by said retaining means (16) in the absence of relative pressure of gas.  2. Device according to claim 1, characterized in that the shutter assembly (13) comprises a retaining means (16) made at least partially of a material having a significant elasticity, of the elastomer type or the like, and a valve obturation (17) able to cooperate with the seat (15).  3. Device according to claim 1 or claim 2, characterized in that the retaining means (16) comprises a ring (14), substantially toroidal, of shape adapted to the shape of a housing groove (12) integral with the body (9) and at least two arms (18) joined together by a fixing ring (19).  4. Device according to claim 3, characterized in that the shutter valve (17) has a shape cooperating with that of the fixing ring (19), to be held by the fixing ring (19) substantially along the axis of revolution of the substantially toroidal ring (14).  5. Device according to claim 3, characterized in that the retaining means (16) comprises three arms (18) of substantially rectangular cross section and having a substantially spherical curvature profile.  6. Device according to claim 4, characterized in that the shutter valve, on the side opposite to a surface (26) having an aerodynamically shaped profile, a hollow shape (28), so as to reduce the mass of the valve shutter (17).  7. Device according to one of claims 1 to 6, characterized in that the body (9) is made inseparable from the pipe made of rigid material by crushing a deformable ring (2) engaged on one end (1) of form adapted, for example having grooves, rigid pipe, so as to ensure the external sealing of the pipe.  8. Device according to claim 7, characterized in that the crushing of the ring (2) is obtained by means of a nut in two parts (3, 4) made integral with one another by means of joining such as a shear pin (5).  9. Device according to claim 8, characterized in that the radially outer part (4) of the nut is able to rotate freely after complete crushing of the ring (2) and rupture of the securing means (5).  10. Device according to claim 8 or claim 9, characterized in that in the position (B) of crushing the ring (2) the radially outer part (4) of the nut has a form overlapping the part radially inner (3) so as to prevent any introduction of a tool capable of operating the radially inner part (3).