SEALING TIGHTNESS TESTING DEVICE

Abstract

A sealing tightness measuring device and a pressure-retaining capability measuring gauge for a pressure container or system is provided. A pressure is produced against the testing fluid inside a piston cylinder communicated with the tested container or system by an assembly including a weight, a piston, and a piston cylinder successively arranged through a coaxial plumb bob. An equation R.sub.L=pt/C is used to represent the sealing tightness of the pressure container or system. The equation pt=p(p0.5p)t/p is used in the pressure-retaining capability measuring gauge to express the pressure-retaining capability, wherein p is the fixed testing fluid pressure, t is the elapsed time for the fluid to leak completely, C is the volume of the pressure container or system, p is the drop value of the pressure, and t is the elapsed time for the pressure to descend from p to (pp) caused by the leakage.

Claims

1. A sealing tightness measuring device for a pressure system comprising: an assembly comprising a weight, a piston, and a piston cylinder; wherein the weight, the piston, and the piston cylinder are successively arranged through a coaxial plumb bob to produce a fixed testing fluid pressure p against testing fluid inside the piston cylinder communicated with a tested container or system; wherein the sealing tightness is measured by measuring a leakage resistance; the leakage resistance R.sub.L=p/I.sub.L=pt/C, p is the fixed testing fluid pressure of the pressure system, I.sub.L=C/t is a volume of a testing fluid leaked from the pressure system in per unit time; a ratio of a total gravity G of an assembly of the weight and the piston to a cross-sectional area A of the piston cylinder G/A is the fixed testing fluid pressure p; a product hA of a drop height h of the weight and piston descending along with a leakage and the cross-sectional area A of the piston cylinder is a volume of leaked testing fluid C; and t is an elapsed time for the volume of fluid C to leak.

2. The sealing tightness measuring device for a pressure system according to claim 1, wherein a fixed testing fluid pressure generating assembly is placed or fixed on a horizontal operating platform of a digital display height gauge through a piston cylinder seat; the digital display height gauge is used to measure and display the drop height h of the weight and piston descending along with the leakage; and a separate timer is used to record the elapsed time t for the volume of fluid C to leak.

3. The sealing tightness measuring device for a pressure system according to claim 1, wherein a fixed testing fluid pressure generating assembly is placed or fixed on a horizontal operating platform of a program-controlled detector which can automatically calculate and at least display and print the leakage resistance after automatically collects calculation parameters C and t of the leakage resistance, through a piston cylinder seat; and each test is performed under a specified or selected value of p until the leakage reaches a specified or selected value of C or t.

4. The sealing tightness measuring device for a pressure system according to claim 2, wherein the piston cylinder and the piston cylinder seat of the fixed testing fluid pressure generating assembly have an integral structure.

5. The sealing tightness measuring device for a pressure system according to claim 1, wherein a channel through which the testing fluid pressure passes to the tested pressure system is provided with a pair of isolating pistons and the piston cylinder for isolating the fluid in the sealing tightness measuring device and the tested pressure system.

6. The sealing tightness measuring device for a pressure system according to claim 1, wherein more than one seal ring is disposed between the piston and the piston cylinder.

7. The sealing tightness measuring device for a pressure system according to claim 1, wherein an overflow groove is attached on an external surface of the fixed testing fluid pressure generating piston cylinder.

8. The sealing tightness measuring device for a pressure system according to claim 1 further comprises at least three weight collapsing protective supports.

9. A pressure-retaining capability measuring gauge for a pressure system, wherein
pt=p(p0.5p)t/p, t is an elapsed time for entire volume of fluid in the pressure system to fully leak out under a fixed pressure p; t is an elapsed time for the pressure to drop from p to (pp) caused by a leakage of the pressure system; a value of pt is automatically calculated and displayed after p, p and t are automatically collected; and each test is performed until the leakage reaches a specified or selected value of p or t.

10. The pressure-retaining capability pt measurement gauge for a pressure system according to claim 9, wherein the value of pt is calculated according to (p0.5p)=p.

11. The sealing tightness measuring device for a pressure system according to claim 3, wherein the piston cylinder and the piston cylinder seat of the fixed testing fluid pressure generating assembly have an integral structure.

12. The sealing tightness measuring device for a pressure system according to claim 2, wherein a channel through which the testing fluid pressure passes to the tested pressure system is provided with a pair of isolating pistons and the piston cylinder for isolating the fluid in the sealing tightness measuring device and the tested system.

13. The sealing tightness measuring device for a pressure system according to claim 3, wherein a channel through which the testing fluid pressure passes to the tested pressure system is provided with a pair of isolating pistons and the piston cylinder for isolating the fluid in the sealing tightness measuring device and the tested pressure system.

14. The sealing tightness measuring device for a pressure system according to claim 4, wherein a channel through which the testing fluid pressure passes to the tested pressure system is provided with a pair of isolating pistons and the piston cylinder for isolating the fluid in the sealing tightness measuring device and the tested pressure system.

15. The sealing tightness measuring device for a pressure system according to claim 2, wherein more than one seal ring is disposed between the piston and the piston cylinder.

16. The sealing tightness measuring device for a pressure system according to claim 3, wherein more than one seal ring is disposed between the piston and the piston cylinder.

17. The sealing tightness measuring device for a pressure system according to claim 4, wherein more than one seal ring is disposed between the piston and the piston cylinder.

18. The sealing tightness measuring device for a pressure system according to claim 5, wherein more than one seal ring is disposed between the piston and the piston cylinder.

19. The sealing tightness measuring device for a pressure system according to claim 2, wherein an overflow groove is attached on an external surface of the fixed testing fluid pressure generating piston cylinder.

20. The sealing tightness measuring device for a pressure system according to claim 4, wherein an overflow groove is attached on an external surface of the fixed testing fluid pressure generating piston cylinder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In the drawings FIGS. 1-3 of the testing device of the present invention, 01 is horizontal plane, 02a, 02b and 02c are rectangular ring seals of final outlet, intermediate outlet and initial outlet of testing pressure, respectively, 03a is hose assembly, 03b is piston cylinder seat, 04 is piston cylinder, 05 is piston (assembly), 06 is weight, 07 is height gauge measuring head, 08 refers to timer, 09 is protective support, 10 is overflow groove, 11 is rising ring, 12 is verification container, 31 is fixing screw of piston cylinder seat (03b).

[0039] FIG. 1 is a device for measuring or verifying the leakage resistance of the connection of piston (05) and piston cylinder (04), wherein 05 (piston assembly) is shown in FIG. 4.

[0040] FIG. 2 is a device for measuring or verifying the total leakage resistance of the testing system which merely includes the pressure outlet of the piston cylinder (04).

[0041] FIG. 3 is a device for measuring or verifying the total leakage resistance of the testing system which includes a pressure output channel formed by 03a and 03b.

[0042] FIG. 4 shows piston assembly (05), wherein 51 is piston body, 52 is O-shape ring sealing, 53 is sealing cone plug of exhaust vent, 54 is thrust washer of spring (55), 55 is plug-sealing recovery spring, 56 is plug-sealing adjusting screw, 57 is piston mounting screw.

[0043] FIG. 5 is a partial view of FIG. 3 where the piston cylinder seat 03b in FIG. 3 is replaced by the piston cylinder seat 03b having isolating piston 13.

DETAILED DESCRIPTION OF THE INVENTION

[0044] The sealing of the normal pressure containers and the systems is to prevent the mutual leakage between the internal fluid and the external atmosphere. The path that causes a mutual leakage of the internal and external fluids is called as leakage path. Each leakage path may have one or a series of seals. The total leakage resistance of all the leakage paths is the sum of the leakage resistances of the serially connected sealing sections. The total leakage resistance of a pressure container or system is the reciprocal of the total leakage derivative, the total leakage derivative is sum of the leakage derivative of each leaking path, and the leakage derivative of each leaking path is the reciprocal of the leakage resistance. Therefore, in order to avoid the intermediate calculation of leakage derivative during some leakage resistance measurements, as shown in FIG. 3, it should be ensured that the total leakage resistance of the testing system which includes the sealing section between the testing fluid pressure generating piston 05 and piston cylinder 04 and the sealing sections 02a-02c of the testing pressure channel is far greater than the leakage resistance of the tested pressure container or system.

[0045] The means to ensure that the leakage resistance of the sealing section between the piston 05 and the piston cylinder 04 is large enough, first, is to use a series of O-shape ring seals to improve the total leakage resistance, and then is to ensure that the liquid fully fills all the spaces among the O-shape rings to make the O-shape rings work synchronously. For this purpose, liquid should always exist at the piston cylinder port during the assembly operation of the piston 05.

[0046] The means to ensure that the leakage resistances of the rectangular ring sealing sections 02a, 02b and 02c including the final outlet, intermediate outlet and initial outlet of the testing pressure is large enough, is to ensure there are sufficiently uniform and sufficient enough plastic deformation in the circumferential direction of the sealing contact surface of the rectangular rings while ensuring that there are sufficiently uniform and sufficient enough elastic deformations in the circumferential direction of the rectangular ring body so that the sealing stress is absolutely greater than the testing pressure. The metal rectangular ring without cold flow can be continuously used in many tests. The polytetrafluoroethylene rectangular ring with cold flow is for disposable use and should be immediately used after the installation, so as to avoid the disappearance of the installation elastic deformation of the rectangular rings due to cold flow, which thus causes the situation that the sealing stress cannot be absolutely greater than the testing pressure.

[0047] However, whether the leakage resistance of a leakage resistance testing system is greater or smaller than the leakage resistance of the testing pressure container or system should be proved by measurement or verification. FIG. 1 shows a device for measuring or verifying the leakage resistance of the connection of piston (05) and piston cylinder (04). FIG. 2 shows a device for measuring and verifying the total leakage resistance of the testing system merely including the pressure outlet of piston cylinder (04). FIG. 3 shows a device for measuring or verifying the total leakage resistance of the testing system including a pressure output channel formed by 03a and 03b. Actually, expect for the large-scale pressure system having many leakage paths, the leakage resistance of the rest of ordinary pressure containers or systems would not be much smaller than the leakage resistance of the testing device system, and a calculation of intermediate leakage derivative is inevitable. Therefore, the leakage resistance of the leakage resistance testing device system must be stable and reliable, and can withstand verification or reexamination.

[0048] An illusion of leakage may appear due to the compressibility of air in a pressure system where liquid is used as the testing fluid, and such phenomenon would affect stability and reliability of the testing. To ensure that the air is fully exhausted from the pressure system, it is preferred to place the testing pressure generating piston cylinder port at the peak point of the pressure system, and install the piston after the testing fluid is slowly filled into the cylinder port. To ensure that the piston 05 can be successfully mounted into the piston cylinder filled with the testing fluid, as shown in FIG. 4, before the assembly operation, the piston mounting screw 57 should be used to push and press against the screw 56 to push the exhaust vent sealing cone plug 53 located at the center of the piston away from the sealing contact position, so that the testing fluid compressed by the installation can be successfully led to the atmosphere. When the last O-shape ring is just mounted into the piston cylinder wall in the assembly, the mounting screw 57 is screwed out so that the sealing cone plug 53 is automatically wedged into the exhaust cone port by the reset structure formed by the washer 54, the spring 55 and the screw 56. To ensure that the leakage resistance of the exhaust vent is infinite, the sealing cone plug 53 should be made of teflon or of metal coated with soft metal or teflon. In order to avoid fake leakage caused by the wedging movement of the sealing cone plug 53, the cone plug and the cone hole should have a sufficient matching length.

[0049] When it is inconvenient to place the testing pressure generating piston cylinder port at the peak point of the pressure system to fill the testing fluid, if an isolating piston is added to the pressure channel of the testing device, the testing system and the tested system may be respectively filled with the same or different fluids. When the existing pressure fluid of the tested system is used to test the leakage resistance, an isolating piston should also be added in the pressure channel of the testing device to facilitate the implementation of the leakage resistance measurement. After the isolating piston 13 is added to the piston cylinder seat 03b shown in FIG. 3, the piston cylinder seat shown in FIG. 3 turn into 03b shown in FIG. 5. The natural limiting end surfaces S1 and S2 of the isolating piston 13 may cause the isolating piston 13 to be unidirectionally compressed. Thus, when the fluid in the tested pressure system is pressurized to an appropriate pressure and thus causes the isolating piston to be pushed to the upper limiting position, after the testing fluid is filled into the testing pressure generating cylinder and the piston 5 is mounted according to the foregoing method, the weight 6 can be added to perform the leakage resistance measurement. The size of the leakage resistance of the isolating piston sealing section only affects the unidirectional pressure-retaining capability of the isolating piston, and does not affect the leakage resistance measurement to be performed.

[0050] There is no volume change when the pressure and temperature of the compressed air are not changed. Therefore, under a fixed testing pressure, as long as the testing pressure generating piston has a sufficient movement that meets the requirement of leakage test, the air may also be used as the testing pressure generating fluid, so as to make the test convenient. When the air is used as the testing pressure generating fluid, the liquid resulting in a synchronous deformation of the O-shape rings may be filled among the O-shape sealing rings of the testing pressure generating piston 05. When liquid overflows in the assembly involving the testing pressure generating piston 05, a liquid overflow groove 10 should be attached to the outer surface of the piston cylinder 04 and even a drain pipe should be attached at the bottom of the overflow groove.

[0051] The leakage resistance and leakage resistance calculation equation of each standard sealing structure can be determined by using the leakage resistance measuring device, and the leakage resistance R.sub.L of the pressure container or system can be calculated according to the standard sealing used and its series-parallel connection. Therefore, on the basis that the leakage resistance R.sub.L, pressure-retaining capability pt and volume C of the pressure container or system are respectively measured by using the leakage resistance measuring device, pressure-retaining gauge and measurement apparatus, and with reference to the theoretical calculation value, the actual measured value and the equation CR.sub.L=pt, the rated volume C, the minimum leakage resistance R.sub.L and the minimum pressure-retaining capability pt can be determined. For the stereotypes products with known volume C, leakage resistance R.sub.L and pressure-retaining capability pt, merely the pressure-retaining capability gauge is required to test whether the pressure-retaining capability is qualified or degenerated in the factory acceptance and operation monitoring.

[0052] When the pressure-retaining capability gauge is used to test the pressure-retaining capability value of a pressure container or system, a double block-and-bleed valve (DBB valve) should be used. The block-and-bleed valve allows its middle channel chamber to communicate with the atmosphere after synchronously cuts off the connection with two pressure containers or systems respectively located at its left and right sides. Therefore, the use of the opening state of the block-and-bleed valve allows the tested pressure container or system to communicate with the pressure fluid or pressure source to obtain the testing pressure. The releasing state of the double block-and-bleed valve is used to implement the pressure-retaining capability test for the pressure container or system. The leakage path that connects the double-and-bleed valve and the atmosphere through middle channel chamber is also a leakage path that blocks the tested container or system.