WO2012050432A2

WO2012050432A2 - Mechanical seal static air test apparatus

Info

Publication number: WO2012050432A2
Application number: PCT/MY2011/000230
Authority: WO
Inventors: Bin Zainal Abidin Azhar
Original assignee: Bin Zainal Abidin Azhar
Priority date: 2010-10-11
Filing date: 2011-10-11
Publication date: 2012-04-19
Also published as: MY154428A; WO2012050432A3

Abstract

An apparatus for performing a mechanical seal test, comprising a housing (301) defined by a top, bottom and side walls; an adapting means (307) forming a part of the top wall, having a central aperture for accommodating a test sample and being replaceable to allow seals of different sizes to be tested; a pressing plate (303) mounted above the top of the housing (301) and movable towards and away from the top wall; and a plurality of clamp members (311) extending downwardly from the bottom surface of the pressing plate (303), such that the clamp members (311 ) can clamp the test sample against the top wall when the pressing plate (303) has been moved towards the top wall to bring the clamp members (311) into contact with the test sample.

Description

MECHANICAL SEAL STATIC AIR TEST APPARATUS FIELD OF INVENTION

The present invention relates to an apparatus for performing a mechanical seal static air test. More particularly, the apparatus is used for testing a sealing device for a pump's rotating shaft where fluid is employed to generate pressure. The apparatus is used on pump site to help determine the quality of static sealing function or in some cases to restore the quality of static sealing function.

BACKGROUND OF THE INVENTION

Mechanical seals are means for controlling leakage in a process. These seals are commonly used in various types of fluid handling equipments such as pumps, which have a rotating shaft and a fluid chamber. One of the seal rings is mounted on the shaft thus it is rotating with the shaft, while the other seal is static, mounted on the seal housing and hence the seal prevent leakage between the rotating shaft and the housing.

Previous models of test rigs are mostly simple apparatus to indicate decrease in pressure after a certain period of time. Analog pressure gauges are used to sense the pressure drop and the result is solely based on the judgments of the technician or engineer in charge.

There are numerous conventional testing methods in the prior arts which relate to seal testing, in which this method presents several limitations. US Patent No. 3546923 disclosed an apparatus for indicating leaks in an annular seal and include a source of pressurized air being selectively controlled and monitored by a set of controlling valves and air gauges. However, this system only depends on the observer to monitor the test without a constant data collection and recording.

Another mechanical seal leak detector is disclosed in US Patent No. 2003015840 where this invention pertains to an assembly for detecting low rates of liquid leakage across the seal rings of the mechanical seal. Although this apparatus incorporates fiber optic sensors and a computer to monitor the leakage, the system will only generate notification after the leakage rate exceed a certain threshold value and it may not be suitable for applications which requires high quality sealing. China Patent No. 201051040 relates to a leakage detection device which is simple in structure, low cost and strong in adaptability. However, this device is suitable for seals in gas handling equipments. The prior arts mentioned mostly refer to conventional testing methods and apparatus which can only cater to a specific type of seals. Accordingly, it is desirable for the present invention to provide a test apparatus which can overcome the drawbacks of the prior arts while still maintaining the simplicity and user friendly feature. The invention shall also provide a constant and reliable monitoring system to ease user's recording. SUMMARY OF INVENTION

Accordingly, it is a primary object of the present invention to provide an apparatus for mechanical seal test with a plurality of embodiments to determine the quality of static sealing function or to restore the quality of static sealing function in accordance with the API (American Petroleum Institute) standard.

It is another object of the present invention to provide an apparatus for mechanical seal test with a set of changeable adapters and adjustable clamping means to accommodate testing of various sizes of mechanical seals. It is yet another object of the present invention to provide an apparatus for mechanical seal test which is capable to test all types of single and double mechanical seal.

It is yet another object of the present invention to provide an apparatus with a hollow feature to reduce its weight and thus making the apparatus more portable.

It is further another object of the present invention to provide an apparatus which has the flexibility to be operated in manual mode apart from the automatic seal testing operation.

Yet another object of the present invention to provide an apparatus with incorporated sensors and control system for constant, reliable and real time monitoring system to ease user's recording during the test. Further embodiment of the present invention is to provide an apparatus for mechanical seal test having user-friendly features and simplicity to ease operations.

At least one of the preceding objects is met, in whole or in part, by the present invention, in which one of the embodiments of the present invention describes an apparatus for performing a mechanical seal test, comprising a housing (301) defined by a top, bottom and side walls; an adapting means (307) forming a part of the top wall, having a central aperture for accommodating a test sample and being replaceable to allow seals of different sizes to be tested; a pressing plate (303) mounted above the top of the housing (301) and movable towards and away from the top wall; and a plurality of clamp members (311) extending downwardly from the bottom surface of the pressing plate (303), such that the clamp members (311) can clamp the test sample against the top wall when the pressing plate (303) has been moved towards the top wall to bring the clamp members (311) into contact with the test sample. In a preferred embodiment of the present invention, the mechanical seal test apparatus further comprises a control system (100) connected to the housing (301) through a temperature sensor probe conduit (305) and a pressure sensor probe conduit (306) to give real time data which are displayed on a panel screen (219). This control system (100) is being governed by a Programmable Logic Control (PLC) (218).

The present preferred embodiments of the invention consists of novel features and a combination of parts hereinafter fully described and illustrated in the accompanying drawings and particularly pointed out in the appended claims; it being understood that various changes in the details may be effected by those skilled in the arts but without departing from the scope of the invention or sacrificing any of the advantages of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS These and other features, aspects and advantages of the present invention will be more fully understood when considered with respect to the following detailed descriptions, appended claims and accompanying drawings wherein:

Fig. 1 shows the anisometric view of the invention's instruments and control system. Fig. 2 shows the schematic representation of the invention's instruments and control system.

Fig. 3 shows the diagram of the apparatus for mechanical seal static air test.

Fig. 4 shows the explode view of testing chamber.

Fig. 5 shows the explode view of testing chamber assembly with supporting stud member and holder.

Fig. 6 shows the explode view of mechanical seal pressing plate. DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the invention shall be described according to the preferred embodiments of the present invention and by referring to the accompanying description and drawings. However, it is to be understood that limiting the description to the preferred embodiments of the invention and to the drawings is merely to facilitate discussion of the present invention and it is envisioned that those skilled in the art may devise various modifications without departing from the scope of the appended claim.

The present invention discloses an apparatus for performing a mechanical seal test, comprising a housing (301) defined by a top, bottom and side walls; an adapting means (307) forming a part of the top wall, having a central aperture for accommodating a test sample and being replaceable to allow seals of different sizes to be tested; a pressing plate (303) mounted above the top of the housing (301) and movable towards and away from the top wall; and a plurality of clamp members (311) extending downwardly from the bottom surface of the pressing plate (303), such that the clamp members (311) can clamp the test sample against the top wall when the pressing plate (303) has been moved towards the top wall to bring the clamp members (311) into contact with the test sample.

As shown in Figure 3, the mechanical seal test apparatus consists of four main parts which are the housing (301), the pressing plate (303), adapting means (307) and the supportive structures of the apparatus. The housing (301) is preferably to be cylindrical in shape forming a sealed chamber for the testing process. The test piece which is usually an assembled mechanical seal is then placed on top of the adapting means (307) which forms the top portion of the housing (301). The adapting means (307) is designed in such a way to accommodate different sizes of seals to be tested. The adapting means (307) is changeable, depending on the size of the seals. This design provides a flexibility to the testing process as various sizes of seals can be tested using the same housing (301) as the testing chamber.

Another preferred embodiment of the present invention discloses that the apparatus further comprises a plurality of stud members (302), extending from the top wall, along a peripheral region of the housing (301) and a holding plate (304) to hold the housing (301) and the pressing plate (303) in place.

With further reference to Figure 3, the housing (301) is attached to the pressing plate (303) through a plurality of stud members (302). Preferably, three stud members (302) are used and are placed equidistant to each other so that the gap in between each member is optimized. This is to allow easy handling for the operators to assemble the mechanical seal on top of the adapting means (307). The stud members (302) are placed at 120° to each other along the peripheral region of the housing (301). With this equidistant configuration, the stud members (302) can give uniform force distribution to the top of the housing (301 ).

A holding plate (304) attached on top of the stud members (302) is preferred to have a hollow feature to reduce the weight of the test rig, making it more portable. The holding plate (304) is designed to have an outer rim and a center support with three bars at equidistant extending from the rim to the center support. This shape ensures that the holding plate (304) can withstand forces and at the same time being relatively light. In addition to that, the pressing plate (303) is secured to the apparatus by a leveling pole (309) which is attached to the holding plate (304) through its center support. Preferably, a jog handle (310) is used to position the pressing plate (303) accordingly. The jog handle is attached to the leveling pole (309) which is threaded and is used as a mechanical power screw to transfer the rotational motion of the jog handle (310) to linear motion. This moves the pressing plate (303) vertically up and down. Nevertheless, without using a jog handle (310), the pressing plate (303) can also be positioned by other means. One example is through hydraulic or pneumatic system, where the pressing plate (303) can be positioned by the automated controller. Another example would be an electrically-controlled system for the pressing plate (303). In other words, the task to position the pressing plate (303) is not limited to a specific method. The pressing plate (303) can also be replaced by a pedestal-like structure to suit the design respectively.

To further secure the test piece in place, there is a plurality of clamp members (311) extended downwardly from the pressing plate (303). The clamp members (311) must be versatile to suit various types of mechanical seals. Preferably, these clamp members (311) should be able to be radially adjustable to meet various sizes of mechanical seals. These members can also be adjusted vertically by means of threading screw to accommodate uneven surfaces on the test piece.

In one of the preferred embodiment of the present invention, the mechanical seal test rig comprises a control system (100) connected to the housing (301) through a temperature sensor probe conduit (305) and a pressure sensor probe conduit (306) to give real time data which are displayed on a panel screen (219), wherein the control system (100) is being governed by a Programmable Logic Control (PLC) (218). In addition to that, the control system (100) further comprises a plurality of pressure indicators (210, 211) which have small predetermined scale in conformance to API standard; means for controlling and regulating air pressure (204,205,206,207,212,213) supplied to the housing (301); and means for sensing pressure and temperature (214, 215, 217) of the sealed housing (301) and the test sample's chamber.

Referring to Figure 1 and 2, a commercially available pressure regulator (204) is preferably used to control the amount of high pressure flow from the compressor to be reduced to a safe level for mechanical seal static applications. It is usually included with the pressure gauge to monitor the allowable pressure release from the regulator. To avoid unstable pressure with a back flow which disturbs the testing process, a check valve (205) is installed to allow compressed air to flow only in one direction. The stable pressure is then passed to the two different solenoid proportional valves (206, 207). An Electromagnetic activated control valve (Solenoid proportional valve BURKERT 2824) is preferred because it can be controlled servo mechanically by PLC (218) commands. The control valve can control and regulate the rate of flow proportionally according to the user requirements. The proportional valve (206) is used to channel the compressed air to the fixture (220). The air will then run through the analog pressure gauge indicator (210). The analog pressure gauge indicator used in the apparatus has a sufficiently small scale of 0.2 bar or 2 psi. This verifies that the gauge indicators are in conformance to API Standard 682/ISO 21049. A digital pressure sensor (214) is positioned near to the testing chamber to make sure the pressurized air into the chamber is precise to the exact value specified.

On the other hand, the proportional valve (207) will channel the air to the mechanical seal (test piece) chamber. Before entering the mechanical seal (test piece) chamber, the air will run through analog pressure gauge indicator (211) and the air pressure will be monitored by digital pressure sensor (215). Preferably, KEYENCE AP-C33W pressure sensor is used as the sensing device to indicate pressure in both of the mechanical seal (test piece) chamber and in the testing chamber. To ensure that the pressure supplied by the valve is the same with the pressure in the chamber (calibration ease), the pressure indicator on the pressure sensor (215) and analog pressure gauge (210) is used to compare the result displayed on the touch panel screen (219).

The solenoid proportional valve (206,207,212, 213) and digital pressure sensor (214, 215) are controlled by the PLC (218). Preferably, KEYENCE KV-3000 programmable logic controller (PLC) is used to control the flow of operations of the apparatus. It is programmed accordingly based on the flow of the tests to ease equipment handling and testing processes. For data display, the PLC (218) will be integrated with the touch panel screen (219) to display a simultaneous result. The thermocouple (217) is used to sense the stuffing box temperature in the testing chamber during the test. Preferably, the thermocouple type K 0 °C -100 °C is used as the sensing device because it is crucial to eliminate the doubts that any pressure drop occurrence is due to the temperature variations. Signals from the thermocouple (217) will be sent directly to the PLC (218) and will be displayed on the panel screen (219) concurrently.

After the pressurized and holding state, the PLC (218) will send a signal to the solenoid proportional bleed valve (212, 213) to release the pressure gradually. The results obtained will be shown on the touch panel screen (219). All modifications and system controlling are completed by using the touch panel screen (219). Preferably, a KEYENCE VT3-S 10 display terminal is used as part of the pressure tester system and to be integrated with the PLC (218) for display and printing purposes. Any test session can easily be operated through the touch screen and will run automatically. Upon completion of the test, there are options to save the test data or to print out the results.

Preferably, the mechanical seal static air test apparatus should be able to operate in manual mode. The ball valves (208, 209) have the same function as the solenoid proportional valves (206, 207). The ball valve (208) channels the air to the testing chamber and the valve will open slowly by monitoring the analog pressure gauge indicator (210) or the digital pressure sensor (214). On the other hand, the air channeling from the pressure inlet to the seal chamber is controlled using a ball valve (209). The air flow is then monitored by analog pressure gauge indicator (211) or digital pressure sensor (215). To release the testing chamber pressure, the ball valve (216) is open slowly until the pressure gauge (211) or pressure sensor (215) indicates 0 Psi. For releasing the sealed chamber pressure, the solenoid proportional bleed valve (213) is activated. Similarly, the results of the test will be shown on the panel screen (219).

In addition to that, Figures 4, 5 and 6 illustrates further details of the components and features embodied in the design of the mechanical seal static air test apparatus. With reference to Figure 4, the bottom flange (401) of the housing (301) has a grooving feature (402) to accommodate the fittings of a chamber wall (403). This grooving feature (402) will provide an alignment and guide for the chamber wall (403) to be fitted to the bottom flange (401) so that these two parts have the same concentricity when assembled. The second grooving feature (404) on the bottom flange (401) is design to accommodate an O-Ring (405) which provides sealing to ensure that air does not leak through this connection. Preferably, eight hex socket screws (406) were used to tighten the connection between the chamber wall (403) and the bottom flange (401).

With further reference to Figure 4, an upper flange (407) is placed on top of the housing (301), having a slot (408) at the bottom to fit onto the chamber wall (403). Similar to the previously mentioned grooving feature (404), the slot (408) provide an alignment and guide for the upper flange (407) to be fitted to the chamber wall (403). The chamber wall (403) and the upper flange (407) are preferred to be welded together to close the connection and to ensure air does not leak through the connection. The top part of the upper flange (407) has a second slot (409) which is to accommodate the fix support adapter (410). This slot (409) will provide a guide to place the fix support adapter (410) on top of the upper flange (407). To accommodate a second O-Ring (412), another groove (411) is added on top of the slot (409). This O-Ring is used as a sealing element for the connection between the fix support adapter (410) and the upper flange (407).

Similarly, the top part of the fix support adapter (410) has another slot (413) and a groove (414) as of the upper flange (407). This slot (413) is designed to accommodate and provide a guide to place the adapting means (307), while the groove (414) is for a third O-Ring (415). These O-Rings (405, 412,415) provides sealing for the respective connections to provide a sealed chamber. The adapting means (307) is placed within the slot (413) so that it is levelled with the fix support adapter (410) and the upper flange (407). Preferably, these two adapters (307,410) are used together to provide a more flexible design. The fix support adapter (410) is maintained for all types of mechanical seals whereas the adapting means (307) is changeable, depending on the sizes of the seals. Therefore, a set of changeable adapters with different inner diameters should be used to meet a variety of mechanical seals.

In another preferred embodiment of the present invention, the supportive structures of the apparatus are secured to the housing (301) using screws of different threading and hex nuts to tighten the connections. These structures are further illustrated in Figure 5. In addition to that, Figure 5 shows the holding plate (304) and the stud members (302) attached to the assembled housing (301). The upper flange (407) of the housing (301) has three threaded holes (501) that are placed preferably at 120 degree to each other to match the arrangements of the stud members (302). The stud members (302) are cylindrical in shape and are designed with a larger end for the unthreaded area (503) compared to the threaded ends (502, 506) so that there is a flat surface (504, 508), separating the unthreaded area (503) and the threaded ends (502,506). To accommodate the threaded end (502) of the stud members (302), the holes on the upper flange (407) are preferably threaded with a 5/8 - 11 UNC. The stud members (302) are mounted to the housing (301) by inserting the threaded ends (502,506) into the holes (501) on the upper flange (407) until the flat surface (504) meets the housing's (301) upper flange (407). This will ensure the stud members (302) stand at 90° to the upper flange (407). Preferably, a hex nut (505) is used to tighten the connections firmly. Similarly, the top end of the stud members (302) have the same design, the top threaded end (506) will provide a guide for the holding plate (304) to be placed on top of the stud members (302). There will be three corresponding holes (507) on the holding plate (304) to accommodate the stud members (302). When the holding plate (304) is placed on top of the stud members (302), the top flat surface (508) of the stud member (302) will meet the flat surface of the holding plate (304). This will ensure the holding plate (304) is placed in parallel with the chamber's upper flange (407) surface. To further tighten the connection, a hex nut (509) similar to the bottom connection is preferably used.

For the versatility of the apparatus, the clamp members (311) as explained earlier, allows radial and length adjustment to suit various types of mechanical seals. In order to be adjustable, several mechanical features are incorporated into the design of the clamp members (311) and the pressing plate (303). Figure 6 shows in detail the components and features of the pressing plate (303) and the clamp members (31 1 ). The pressing plate (303) comprises of a lower (615) and upper plate (609), having numerous slots to hold the clamp members (311 ) in place. However, the pressing plate is not limited to that particular structure and can take any form depending on the design of the pressing mechanism of the apparatus. With further reference to Figure 6, the clamp members (311) comprises a holder (611), a rod (630) and a cover (625). The holder (611) has a cylindrical body (613) and a flat head feature (612) at the first end. The flat head feature (612) is preferably to have a squarish shape in which the ends are capped off with semicircles. This shape can hold and support the holder (611) in the slot (614) on the lower plate (615). The slots (614) on the lower plate (615) have two step sizes each; the bigger slot size (616) is designed to accommodate the holder's squarish feature, whereas the smaller slot (617) is designed to give a pathway for the cylindrical feature (613) to be inserted. The holder (611) is inserted into the slot (614) on the lower plate (615) in such a way that the squarish feature provide a support and allow the holder (611) to move radially along the slot (614). Upon inserting all holders (611) into their respective slots (614), the upper plate (609) and the lower plate (615) are attached together forming the pressing plate (303), and the connection is preferably secured by M5 x 0.8 hex socket screws (620). The rod (630) has a threaded area (622) and an unthreaded end (623), where the unthreaded end (623) will be pressed into a cover (625). Preferably, the cover (625) is made from soft rubber to protect the surface of the test piece from scratches when clamping it against the testing chamber. The unthreaded end (623) is designed to tightly fit into the hole (624) of the cover (625) without the use of fastener. The threaded area (622) is inserted into the threaded hole (627) on the squarish feature of the holder (611). The first end of the rod (630) is preferred to be a threaded end (628) with a feature of the hex socket screw to allow operators to tighten the clamp members (311) using a wrench from the upper plate's (609) slot (629). With this extra feature, the clamp members (311) can be adjusted vertically without needing to disassemble the pressing plate (303).

With further reference to Figure 6, the jog handle (310) as explained earlier is preferably to be made from rubber and is locked at the top end of the levelling pole (309). Functioning as a handle to ease the operations of clamping the test piece, the jog handle (310) should have an ergonomic design. Preferably, the jog handle (310) should be made round, attached to its center (602) by six solid rubber bars (603), similar to the design of a wheel, to provide easy handling for the operators to hold on to and rotate during assembling of the test piece to the apparatus. However, the jog handle (310) can also be designed to a certain shape which is deemed suitable to be used. The levelling pole (309) is preferably threaded with 7/8 - 9 U C. The bottom end (604) of the leveling pole (309) is designed to have a smaller diameter size and has another screw thread (618) to be fitted into the leveling base (605). As explained earlier, there are other methods to position the pressing mechanism and therefore, a levelling pole (309) may not be needed, but rather a pushing means with incorporated dampers to push and release the pressing mechanism to a certain position.

The leveling base (605) has a cylindrical shape with a hole (626) in the center and four holes (610) placed at 90° along the edge. The center hole (626) is to accommodate a place for the bottom end (604) of the leveling pole (309). Preferably, to ensure that the connections are firm, a hex jam nut (606) and a washer (607) are used. The leveling base (605) is then fitted into a slot (608) on the upper plate (609). Hex socket screws (621) are used to tighten the connection between the leveling base (605) and the upper plate (609). The invention possesses a high product value as it has the flexibility to allow testing of various sizes of seals. The apparatus can determine the quality of static sealing function or restore the quality of static sealing function in accordance with the API (American Petroleum Institute) standard. Besides, the simple design and user-friendly features eased the procedures of the static air test for mechanical seals.

Although this disclosure has described and illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to those particular embodiments. Rather, the invention include all embodiments which are functional or mechanical equivalence of the specific embodiments and features that have been described and illustrated.

Claims

1. An apparatus for performing a mechanical seal test, comprising:

a housing (301) defined by a top, bottom and side walls;

an adapting means (307) forming a part of the top wall having a central aperture for accommodating a test sample and being replaceable to allow seals of different sizes to be tested;

a pressing plate (303) mounted above the top of the housing (301) and movable towards and away from the top wall; and

a plurality of clamp members (311 ) extending downwardly from the bottom surface of the pressing plate (303), such that the clamp members (311) can clamp the test sample against the top wall when the pressing plate (303) has been moved towards the top wall to bring the clamp member (311) into contact with the test sample.

2. An apparatus for performing a mechanical seal test according to claim 1, further comprising:

a control system (100) connected to the housing (301) through a temperature sensor probe conduit (305) and a pressure sensor probe conduit (306) to give real time data which are displayed on a panel screen (219), wherein the control system (100) is being governed by a Programmable Logic Control (PLC) (218).

3. An apparatus for performing a mechanical seal test according to claim 2, wherein the control system (100) further comprises a plurality of pressure indicators (210, 211) which have small predetermined scale in conformance to API standard; means for controlling and regulating air pressure (204,205,206,207,212,213) supplied to the housing (301); and means for sensing pressure and temperature (214, 215, 217) of the sealed housing and the test sample's chamber.

4. An apparatus for performing a mechanical seal test according to claim 1 further comprises a plurality of stud members (302), extending from the top wall, along a peripheral region of the housing (301) and a holding plate (304) to hold the housing (301) and the pressing plate (303) in place.

5. An apparatus for performing a mechanical seal test according to claim 1 wherein the clamp members (311) comprises a holder (611), a rod (630) having an external thread (622) for rotating the rod (630) within the holder (611) and to allow length adjustment of the clamp members (311), and a cover (625).

An apparatus for performing a mechanical seal test according to claim 5 wherein the holder (611) having a flat-head feature (612) which fits into a slot (616) to allow radial adjustment of the clamp members (311) to suit various sizes of the test sample.

7. An apparatus for performing a mechanical seal test according to claim 4 wherein the stud members (302) are placed at a predetermined angle to each other to maximize the gap between each member (302) for easy handling.

8. An apparatus for performing a mechanical seal test according to claim 1 further comprises a plurality of O-rings (405, 412, 415) provides sealing for any connection of the housing (301) to ensure air does not leak out the housing (301).