FR2518215A1 - pressure buffer for pipe circuit - has hollow bell shaped chamber attached to valve and diaphragm with calibrated hole - Google Patents

Abstract

The automatic buffer controls pressure variations in pipe network (R) and eliminates dangerous pressures. It has a ball shaped part (1) fixed on a grille (3) on an inlet pipe (7). A deformable, flexible, membrane (2) is inserted between the bell part and the grille. In the centre of the membrane is a flap valve (5) with a hole (6) forming a diaphragm. When the membrane is subjected to pressure variations, the upstream side of the valve and the interior downstream bell cause automatic opening and closing as required. The hole (6) is calibrated.

Description

AUTOMATIC SURPRISE SCREEN
for the tranquilization of the pressure regime
donations a network of pipelines
The object of the present invention is to provide an overpressure clipping device for the purpose of tranquilizing the sudden variations in pressure that occur in the conduits conveying a fluid (water for example) and whose load is subjected to wavy variations causing disturbances throughout the network, of the ram type, and consequently producing discontinuous and intermittent intermittent stress effects in a very short time.

 It has already been proposed for pressurized piping systems of the types known by the name of: safety valve, disc or valve shutter and safety bell or counterbalanced anti-ram valve, gas capacity or on springs.

 These above-mentioned apparatus have as a common feature "a calibration of the apparatus" at a fixed pressure threshold; generally, the maximum operating pressure, plus 5: o of this pressure. Consequently, the overpressures clipped by these devices are always greater than the pressure. tare, but never below it.

 However, the experience in applied hydraulics shows that the most dangerous mechanical stresses or fatigues are not necessarily generated by the relatively high pressures relative to the maximum operating pressure but most often by the speed of the variations that are poorly assimilated by the materials constituting the body of pipes and joints. Experience shows that a pipe can burst under a low pressure subjected to numerous and brutal variations and withstand greater pressure with gradual and gentle variation.

 The known apparatuses therefore play only a rale of pressure limiter; the apparatus which is the object of the invention ensures the function of sudden pressure surge clipper on all the intermediate pressure thresholds proposed during operation, without limitation, the points Po to P. This function is automatic and autonomous.

 The apparatus, according to the invention, does not require any particular calibration and is reduced to a bell mounted on a grid integral with a fluid inlet pipe between which is inserted a flexible membrane in the center of which is located a diaphragm calibrated orifice, the diameter of which is fixed according to the importance of the average flows transited in the network and the average level of the pressures in a normal operating mode; a sealing valve completes the assembly, glued to the flexible membrane; it is crossed itself by the central orifice of the diaphragm.

 The device that constitutes the entire pressure relief clipper is simple since it does not use any known type of element, such as gas capacity, spring or against weight and that, moreover, its operation does not is dependent on no taring or limiting.

 In addition, the motor element of the valve # mounted on the éeréteurJest the same pressure of the fluid that it is responsible for regulating. So a manufacturing economy and energy.

 The object of the invention is achieved when, mounted on a network of pipes subjected to sudden changes in pressure in a short period of time, a series of recording pressure gauges placed at points which are particularly vulnerable to said network, show by the restitution of the pattern of the pressure regime that these vary in a progressive way positively without jerk or voltage in peak of known type. It can be seen that the phenomenon that is detrimental to the proper functioning and good resistance of the constituent elements of the network has disappeared.

 The apparatus which is the subject of the invention will be mounted in one or more copies according to the size and length of the pipes without limitation of number and characteristic dimensions of any kind.

 The mounting points of the pressure limiter will necessarily be the highest in altitude on the pipe layout because the top bell of the device. is a capacity of air or other gas that feeds on the gas dissolved in the fluid constituting pockets in the high points of the pipes.

 On the other hand, the underpressures or negative voltages are automatically canceled by both the air inlet valve (s) which are always mounted on a pressurized network and the reaper who intervenes by his / her action. 'damper.

 The limiter of the overpressures which is the subject of the invention operates according to the principle of known physics capabilities communicating with each other and # filling or emptying via a fixed orifice e diameter. The equilibrium or the imbalance of the pressures being reached on either side of these capacities at more or less long term in the time, this duration of reaction to the balancing or inertia of operation being directly function of the level of the pressure and the size of the orifice of the diaphragm mounted on the membrane separating said capacitors, one of these capacities being the upper bell of the limiter, the other being the same conduct of the network to be regulated.

 It is noted that the limiter operates when the actipn of the pressure in the pipe suddenly unbalance the membrane provided with the valve that closes the tubing.

 A certain quantity of fluid is then discharged outside the pipe when the membrane placed in imbalance lifts the shutter valve; the pressure is instantaneously broken or clipped.

While the ejection of the fluid occurs, one notices
that also that the upper bell of the clipper goes pro
gressively in equilibrium with reference pressure
of the pipe through the orifice provided for in
this effect ; when the balance is achieved again, the mem
brane is pressed against the grate; the flapper attached to it
closes the tubing and the assembly is ready for use again
from a new reference level of pressures.

The following description refers to the accompanying drawings
which represent, without any limiting character, one of the
my possibilities of the device, its constituent elements and a
example of drawing of operating curves collected during
experimental model tests (figures marked 1 to 6).

* Figure 1 is a schematic sectional view of lten-
seems of the device; the membrane 2 is represented in two positions: 2.1: open; 2'2: closed, according to the invention.

* Figure 2 is a plan view of the grid evacuated
whose external form as well as those of
res practiced are in no way limiting; the drawing that in
is given having value only as a representative example
among several possibles'and equivalents according to the invention.

FIG. 3 is a plan view of the flexible membrane
and flexible whose drawn form is given as an example
ple without its layout being restrictive according to the invention. The
circular shape usually the most advantageous could
be replaced by any other form without changing the principle
innovation.

 FIG. 4 is a detailed sectional view of the constituent shutter elements such as membrane, valve, seat and orifice on diaphragm. Their shape and size are of value only as an example and are in no way limitative according to the invention. The form given by way of example is generally the most advantageous.

FIG. 5 is a current representation of the phenomenon known from experience of the curve of each of the pressures studied.
Cl - plot of pressure variations in the network when
the clipper is not connected - closed V valve
C2 - plot of pressure variations in the network when
the screen is plugged
C3 - plot of pressure variations in the cloche bell
tor
C4 - Plot of mean reference pressure over a span of
reduced to the duration of the study and corresponds to a
rate requested by users
C5 - plot of maximum service pressure.

 The pressures are on the y-axis.

 Times are plotted on the x-axis.

 The different plots of these curves are only repre- sented by way of example and may, in other conditions; operating modes, espouse other shapes and values knowing that if the principle of the invention is constant, it can adapt to different hydraulic contexts.

 * Figure 6 is a representation of a recovery system mounted on the clipper and allowing, as shown in Figure, a r eam possible.

 This additional equipment is optional and should only be used for valuable or dangerous fluids.

DESCRIPTION OF OPERATION
The operation is carried out in three main phases marked by intermediate stages Phasè 1
Position of the diaphragm 2 closed, valve 5 pressed against the seat of the manifold 7. It is noted that the internal pressure PC3 in the bell C of the limiter is equal to the pressure PC2 prevailing in the network of conduits R to be protected, the whole is in balance. A plateau is crossed when this equilibrium is broken; a hydraulic disturbance causing a sudden overpressure in the network R.

 It is seen according to FIGS. 1 and 5 that the valve 5 is subjected to this overpressure and tends to lift the membrane which it is integral and thereby open the tubing 7 to the outside.

The opening condition will be fulfilled when the following inequality is verified:
PC3 x 52 <PC2 x S5 with: S2 membrane surface subjected to pressure P # C3 and
S5 surface of the upstream face of the valve 5 subjected to the
PC2 pressure.

The opening force is then F i Pu2. 55 - Pt3. S2
o
Phase 2
The membrane is lifted, the valve 5 is detached from the seat 7, the released fluid is discharged either outside (atmospheric pressure), or in a recuperator 9 ~ according to Figure # 6 which represents a recycling circuit 'av' flask "B" buffer between clipper E and discharge pump P.

 During the same time, the pressure PC2 tends to settle in the capacity C of the bell 1 by compressing the concentrated air therein until PC3 = PC2.

 It will be noted that S2> 55 and that if 6 = s2 / S5, closing of the membrane 2 and closure of the seat 7 by the valve 5 when PC3 = PC2 / S (limit state in closing debut).

 Furthermore, the opening time of the clipping depends on the size of the orifice of the diaphragm 6 since the importance of this orifice determines the degree of ease of passage of the fluid in the tubing direction 7 to the bell 1 or vice versa in case of depression.

Phase 3
The membrane in the plating position, the valve 5 gradually presses on its seat 7 while PC3 tends to the value of PC2. The closure will be total and maximum when
PC3 = PC2. We will have: PC2. 55 <PC2. 52.

 The closing force acting in the center of the valve, in the direction 1 to 7, is in this case: Ff = PC2 (52 - S5).

 Furthermore, a closure complementary to the action of the valve is provided by the membrane. 2 which is based on the ring 7b slightly protruding from the grid 3 and is therefore a second shutter that tends to complete the seal of the closed assembly.

Notes For the system to function # it is imperative that S2> S5. However, experience shows that the ratio S2 / S5 = # must be at least #; #, but practically J = 2 is a satisfactory value.

2. / - For that. the system works, the capacitance C of 1 must always be filled with air, its power being naturally supplied by. recovery, high point, gases (example air dissolved in water).

 This presupposes a perfect tightness of the hole 1, an objective which is achieved when, in operation, a part of the fluid (water for example) enters the bell 1 through the orifice 6 of the diaphragm; the membrane 2 flanges - plates 3 and bell 1 is then perfectly airtight ~ for high pressures P> 15 bar or for fluids charged with dangerous gas, the inside of the bell 1 will be doubled by a tight and flexible envelope (rubber or similar material adequate).

 The external diameter of the diaphragm valve 5 must necessarily be less than the outside diameter of the tubing 7. The clearance may be several mm, the experiment shows that 4 mm is an acceptable minimum. limitation of none # so.

4. / - The diameter of the orifice 6 of the diaphragm may vary according to the importance of the mean service pressure, the length of the pipes (reasoning period) as well as transited flow rates.

 Moreover, the membrane must be deformable since, according to FIG. 1, two situations are distinguished 2.1. - open membrane 2.2. - closed membrane.

The material used will necessarily be flexible and flexible while maintaining its essential sealing qualities;
- Any shape of the curve or profile, any suitable material and any particular structure can not change the character of the invention. However, experience shows us that for low pressures, P # 15 bar, the membrane, with a minimum thickness of 1 mm, may be either rubber or plastic, or any other equivalent material.

 For high pressures, P> 16 bar, membranes with a minimum thickness of 2 mm and a very strong material will be recommended. Concentric-wave stainless steel spring-type membranes of known type could be used over a large diameter and for very high pressures: 9 Q325 bar.

The bladder 12 will also be of the same material as the membrane.

Note
The comments from 1 to 5 above do not limit the possibilities or the character or the intrinsic definition of the invention; they are therefore in no way limiting in form, structure or dimensions.

Claims (5)

 automatically open or close the device as necessary.  firstly by the upstream face of the valve 5 and secondly by its inner surface downstream inside the bell 1  - The membrane 2 subjected to pressure variations, in  pierced with a hole 6 forming a diaphragm  - The membrane 2 is provided at its center with a valve 5  on the outskirts of 1 and 3  between 1 and 3 and maintained by 4 bolted flanges  - A flexible or flexible deformable membrane 2 inserted  grid 3 integral with an inlet manifold 7  in the network R, comprising a bell 1 fixed on a  picking by clipping the positive tensions dangerous run  control too fast changes #in a network of con  1. / An automatic pressure limiter "E", intended for  on the network and also according to the materials used.  this valve may be different depending on the pressure values  tubing 7 based on it; the angle '# (Figure 4) of  carrying a calibrated orifice 6 ensures, the closure of the seat of the  characterized in that the valve 5 integral with the membrane 2 and com  2. / - Overpressure preventer according to claim 1  The outside diameter of the valve 5 is smaller than the diameter of the valve.  be 900 and 200 without limitation of any kind  The value of the angle o <will generally be included in The shape of the valve will generally be frustoconical, but any other profile does not alter the character of the innovation. Furthermore, the effect of the valve 5 will be completed by exceeding the tubing 7b (Figure 4) relative to the grid 3, which allows the membrane, by clamping, to seal a second time the tubing 7.  compressed by compressed air c) PC2 - pressure in the network to control the proportion ratio of surfaces 52/55> # 1,2 being satisfied (figure 4).  grid 3 b) PC3 - internal pressure in the capacity of the bell 1 in  3. / - pressure booster according to claims 1 to 2 which operates according to the principle of the difference of the downstream pressures upstream of the membrane through different upstream-downstream incident surfaces, the membrane undergoing three kinds of pressure a) Atmospheric pressure outside on the periphery  4. / - booster of pressure according to claims 1 to 3 which comprises a calibrated orifice 6 in the center of the valve - diaphragm 5 whose object is to relate the capacity of the bell 1 with the network R.  This orifice varies according to the size of the device.  The diaphragm can be removable and interchangeable, without modifying the valve. An axially pierced screw system is recommended but. it is in no way limiting.  ves.  situations or situations, which are not in any way  or lights8 can be adopted, as well as any dimen  tubing 7 (open valve 5) .Different forms of orifices  relating to the passage of the fluid during its ejection by  generally of oblong and radiating type '(FIG.  Meter fixing the bell by bolts 4, holes 8  tubing 7 "and its periphery in limit diau minus mm dia  circle, is provided, in its part between the  candle stitched on the network; the grid, of general shape  via the gousSets fi, the whole constituting a  .h 4 which has a grid 3 secured to the tubing 7 by  Napper - overpressure according to one of the claims of 1  The pressure limiter according to one of claims 1 to  5 comprises a recovery bowl 9 extended by a pipe  evacuator adapted during the recycling of the ejected fluid; 011th  will generally have a circular shape and will settle in a way  optional against the grate through bolts or  #tiges threaded and nuts 4. The set is waterproof.  maximum sealing. His job is optional.  bladder 12 will be welded to the flexible membrane 2 'to ensure  be greater than p:> 15 bar or for hazardous gases. This  these will be set up for the average service pressures  shape as the bell 1 and. dimensions slightly less than 7. / - The pressure limiter according to one of claims des - 6 comprises an envelope or bladder 12 generally of the same  pressures; this air advantageously replaces any other element of known type.  high point of the "R" network) and subject to fluctuations  bell 1 filled with air or any other gas (because bran  fet-automatic engine providing assured by the capacity "C" of the  any counterweight or countervailing gas bottle 'as it exists on existing known types of anti-rams.  simplicity of its realization which excludes any calibration spring,  outside that of the fluid to be controlled; also by  tammeot by autonomous operation, without energy input  according to one of the claims of the & 7 is characterized  The originality of the system. the overpressure clipper  9./- The pressure limiter according to one of revendicati -ons 1 to 8 differs from known types of devices. Commonly called anti-ram, relief valve or safety valve because its regulation at the pressure regime is exerted on the whole scale of the pressures between Po P, maximum (figure 5) - (curve C5 ) whereas existing conventional anti-boilers only control overpressures above the maximum operating pressure.