JPH04228890A - Diaphragm breaking detector - Google Patents

Abstract

PURPOSE: To solve the problem caused by diffusion of suctioned gas in a diaphragm rupture detection device. CONSTITUTION: A diaphragm rupture detection device for a hydraulic pump has two diaphragms held together onto a fixation structure including a circular piece arranged between the diaphragms, with their surfaces being sealed. The inner space between the diaphragms is communicated with at least one detector duct 10 connected to an external detector 11 through an intermediate circular piece. The detector duct 10 has an air duct 13 which can transfer its capacity through capillary duct 14.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an improved system for detecting diaphragm failure in hydraulically controlled twin membrane pumps.

0002

BACKGROUND OF THE INVENTION Hydraulically operated or controlled pumps include one or more diaphragms. This is because the diaphragm is in pressure equilibrium and operates under better conditions than mechanically operated pumps. At least two diaphragms are used to facilitate detection of diaphragm failure by monitoring the pressure in the space between a pair of diaphragms. This space is delimited by the diaphragms themselves and by annular structural pieces placed around the periphery between the diaphragms. A diaphragm is fastened onto the annular piece by two parts of the pump body. This annular piece has a duct opening to the outside. A detection device for detecting the presence of liquid or abnormally high pressure conditions is installed at the outlet of this duct with an annular piece serving as a support for the detection device. Preferably, a check valve is installed on the duct to prevent the contents of the tubing from returning between the two diaphragms. This is especially true if the contents contain gaseous components, which reduce pumping efficiency during the suction stroke.

The above diaphragm failure detection devices have a drawback when the pumped substance is able to diffuse through the flexible diaphragm. This material diffuses gradually during each dispensing stroke, generally in the gas phase. The rupture monitor tube system is filled with this gas which is restrained by a check valve. The pressure reaches a value that prevents the check valve from operating. The space between the diaphragms is occupied by this gas, resulting in a major loss of accuracy in the nominal pumping rate. This is due to the compressibility of the gas causing it to expand and contract during each pumping cycle. Additionally, the pressure may reach the trigger threshold of the diaphragm rupture detection device, thereby generating false alarms, reducing device reliability and requiring unnecessary repairs.

0004

OBJECTS OF THE INVENTION It is an object of the present invention to compensate for the above-mentioned drawbacks and to solve the problems described in French Patent Application No. 2 53.
3,636 and 2,624,922.

[0005]

[Means for Solving the Problems] Improvements in the diaphragm breakage detection device according to the present invention to solve the above-mentioned problems include:
A diaphragm rupture detection device for a hydraulically operated pump having two diaphragms held together in a peripherally sealed manner on a fixed structure including an annular piece disposed between the two diaphragms. characterized in that the inner space communicates via an intermediate annular piece with at least one detector duct connected to an external detector, said detector duct having a ventilation duct for transferring its volume to the atmosphere via a capillary duct. shall be.

[0006] If the diffusion gas is generally toxic, it is advantageous for the ventilation duct to be connected from the capillary duct to a leakage collection duct.

In a preferred embodiment of the invention, in order to facilitate adjusting the permanent leakage to the nature of the suction substance, the detector duct is formed through a part fixed on the annular piece; The part has an internal longitudinal part of the ventilation duct between its outer surface and the detector duct, and the capillary duct is removably connected to the ventilation duct, and the part has an external tube. It is good that it is formed.

In order to facilitate the connection of a leak collection duct for collecting leakage of gas diffusing through the diaphragm, the part has another internal duct having both ends open to its outer side; one of the ends has means for connecting to the other end of said capillary duct;
has connection means to said leak collection duct. The features and advantages of the invention will be better understood from the examples below.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to a partial schematic sectional view of a diaphragm pump including a diaphragm breakage detection device according to the present invention.

In the drawing, the twin diaphragm pump consists of a pumping chamber 1 defined by one of the diaphragms 2 and a pump head 3. The pumping head 3 comprises a suction duct (not shown) and a distribution duct 4. The volume of this pumping chamber changes because the diaphragm 2 is variable and is acted upon by the hydraulic fluid in the working chamber 5. A working chamber 5 is located behind the diaphragm 2 and is delimited by a pump body 6 and a second variable diaphragm 7. The second diaphragm is fixed to diaphragm 2. The pumping head and pump body are held on the intermediate annular piece 8. The periphery of the second diaphragm is fastened therebetween.

When the hydraulic fluid is forced onto the diaphragms 2 and 7, the diaphragms deform towards the walls of the pump head and direct the material in the chamber 1 through the check valve 9 into the distribution duct. Discharge. When the hydraulic fluid is actuated in the opposite direction, the diaphragm is pulled rearward and the pump suctions material that is suctioned into the pumping chamber via the suction duct.

The diaphragm breakage detection device of the present invention has a detection duct 10 extending radially from the intermediate piece 8 and leading to a detector 11. The detector 11 is constituted by a pressure gauge or other sensor or device capable of triggering an alarm signal when the pressure within the detection duct 10 exceeds a predetermined threshold. At the outlet of the annular piece 8, a detection duct 10 prevents the substances contained in the detection duct 10 from flowing back in the direction of the interdiaphragm space when the pressure in the working and pumping chambers decreases during the suction stroke. It has a check valve 12. This check valve is necessary because the substance in the detection duct 10 is derived from a component of the suction substance diffusing through the generally gaseous diaphragm 2. If some gas is present between the diaphragms, it expands and contracts during each pumping cycle, reducing the flow rate through the pump.

This diffusion causes gas to be continuously transferred out of the check valve 12 and into the detection duct 10 in the absence of the ventilation duct 13 of the present invention, which allows continuous leakage from the detection duct 10 to the atmosphere. Pressure increases. This ventilation duct 13 has a capillary duct 14 which measures such leakage, so that in normal operation of the pump, said leakage is substantially equal to the amount of gas entering the detection duct 10 by diffusion from the diaphragm 2. This leakage thus serves to prevent the pressure in the detection duct 10 from becoming too high, while also preventing the check valve 12 from operating properly and reaching the gas that accumulates between the diaphragms. This causes the pump function to deteriorate. Furthermore, the ventilation duct serves to prevent false warning signals from being issued by the detector 11 in the absence of diaphragm failure. If one or more or other diaphragms are ruptured,
The detection duct 10 is filled with a liquid having a higher viscosity than the diffusion gas, and the amount of the liquid increases rapidly. This liquid leakage results in large head losses from the capillary duct 14, allowing the pressure within the detection duct 10 to reach the detection threshold during the dispensing stroke. The rate of liquid leakage to the outside is very low.

In the illustrated embodiment, the ventilation duct 13 has a first longitudinal section 13a formed through the detector support 15. This detector support includes a detection duct 10 and a first
The longitudinal portion 13a communicates with the outside of the support portion 15. A capillary duct 14 takes the form of an external duct of the support 15 and is removably connected to the outlet of the first longitudinal part 13a to adjust said leakage by variation of the capillary, e.g. as a function of the properties of the pumped substance. Alternatively, the same support 15 can be used on the range of the pump, acting as a function of the pump power. The other end of the capillary duct is connected to the second longitudinal part 13b of the ventilation duct 13 in the same way as the support part 15. This other end is likewise open to the surface of the support bar 15 in that it is provided with connection means to a leakage collection duct 16, which collects the aspirated material in the event of a rupture of the diaphragm 2. have the effect of This arrangement is particularly important for pumps used for poisonous substances, since it prevents the release of substances into the atmosphere. The support 15 easily accommodates the improvements of the invention by installing interchangeable capillary ducts 14.

[0015]

By means of suitable control of continuous leakage as described above, the maintenance and adjustment costs of the pump are significantly reduced, and at the same time the risk of deterioration of pump performance due to false alarms is eliminated.

[Brief explanation of the drawing]

FIG. 1 is a partial schematic sectional view of a diaphragm pump of a diaphragm breakage detection device according to the present invention.

[Explanation of symbols]

1. ．． ．． pumping chamber 2. ．． ．． diaphragm 3. ．． ．． pumping head 4. ．． ．． distribution duct 5. ．． ．． working chamber 6. ．． ．． pump body 7. ．． ．． Deformable diaphragm 8. ．． ．． circular piece 9. ．． ．． check valve 10. ．． ．． detection duct 11. ．． ．． Detector 12. ．． ．． check valve 13. ．． ．． ventilation duct 14. ．． ．． capillary duct 15. ．． ．． Support bar (support part)

Claims (4)

[Claims] 1. A diaphragm rupture detection device for a hydraulically operated pump having two diaphragms held together in a peripherally sealed manner on a fixed structure including an annular piece disposed between the two diaphragms, comprising: The inner space between said two diaphragms communicates via an intermediate annular piece with at least one detector duct connected to an external detector, said detector duct having a ventilation duct which conveys its volume to the atmosphere via a capillary duct. A diaphragm breakage detection device comprising: 2. The diaphragm failure detection apparatus of claim 1, wherein said ventilation duct is connected from said capillary duct to a leak collection duct. 3. The detector duct is formed through a part fixed on the annular piece, the part having an inner longitudinal part of the ventilation duct between an outer surface thereof and the detector duct. 2. The diaphragm fracture detection device according to claim 1, wherein said capillary duct is detachably connected to said ventilation duct and is in the form of an external tube of said part. 4. The part has another internal duct having both ends open to its outer surface, one of the ends having means for connecting to the other end of the capillary duct, and 4. The diaphragm failure detection device of claim 3, wherein the other one of the ends has means for connecting to the leak collection duct.