Abstract:
A leak detection system includes a valve assembly having poppet valves disposed in a valve body for selectively closing internal ports for sequentially pressuring a test part from a pressure source, isolating the test part, determining the leakage conditions at the test part and exhausting the test part at completion of the test.

Description:
FIELD OF THE INVENTION 
     The present invention relates to equipment for use in testing leakage in pressure containing vessels or fluid lines, and, in particular, a control valve assembly with interface and microprocessor control for use in leak detection systems. 
     BACKGROUND OF THE INVENTION 
     Manufacturers of hydraulic, pneumatic, and containment equipment customarily test the fluid integrity of their components to ensure safe operation in the field. Standards are generally prescribed for leakage rates at test pressures and times correlated to the desired component specifications. 
     Currently, leak detection systems are an assembly of separate components housed in portable test units. Using a myriad of valves and pneumatic lines a component to be tested is attached to the test unit and independent valves are sequenced to route pressurized fluid, customarily air, to the component, which is then isolated. The leakage rate at the component is then measured and a part accepted or rejected based thereon. The multiple valves and lines may be integrated into a portable test stand for on-site testing. Nonetheless, the pneumatic system is expansive and cumbersome, with each element posing the potential for associated malfunction and leaks. Further, automation of a testing protocol is difficult because of the independent relationship of the components. Where varying test pressures are required for other components, the system must be retrofitted for each such use. 
     For example, the leak detection apparatus as disclosed in U.S. Pat. No. 5,898,105 to Owens references a manually operated systems wherein the testing procedures is controlled by plural manual valves and associated conduit occasioning the aforementioned problems and limitations. 
     Similarly, the hydrostatic testing apparatus as disclosed in U.S. Pat. No. 3,577,768 to Aprill provides a portable unit comprised of a plurality of independent valves and associated lines for conducting testing on equipment and fluid lines. The valves are manually sequenced for isolating test components from a single pressure source. U.S. Pat. No. 5,440,918 to Oster also discloses a testing apparatus wherein a plurality of conventional valving and measuring components are individually fluidly connected in portable 
     Remotely controlled leak detection systems, such as disclosed in U.S. Pat. No. 5,557,965 to Fiechtner, have been proposed for monitoring underground liquid supplies. Such systems, however, also rely on an assembly of separate lines and valves. A similar system is disclosed in U.S. Pat. No. 5,046,519 to Stenstrom et al. US. Pat. No. 5,072,621 to Hassemann. 
     U.S. Pat. No. 5,540,083 to Sato et al. discloses remotely controlled electromagnetically operated valves for measuring leakage in vessels and parts. Separate valve and hydraulic lines are required. 
     In an effort to overcome the foregoing limitations, it would be desirable to provided a portable leakage detection system for testing the fluid integrity of fluid systems and components that includes integrated valving and porting within a compact envelope for automatically controlling a variable testing protocol. The leak detector includes a valve block having internal porting selectively controlled by four identical and unique pneumatic poppet valves for pressurizing the test part, isolating the test part for determining leakage rates with pressure and flow sensors communicating with the porting, and exhausting the test line upon completion of the leakage test. The poppet valves engage valve seats incorporated within the porting. The poppet valves are actuated by pilot valve pressure acting on a pilot piston to effect closure of the valve. The sensors interface with a microprocessor for comparing measurements with the test protocol and indicate pass or fail performance. Upon removal of the pilot valve pressure, the resident pressure in the porting shifts the valve to the open position. The leak detector includes plural inlets for accommodating variable pressure protocols. The leak detector thus eliminates the need for external fluid connections and conduits between the various detector components, eliminates the need for two-way valving actuation, and provides for connection with external test units with a single, easy to install, pneumatic line. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The above and other objects and advantages of the present invention will become apparent upon reading the following detailed description taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a perspective view of a leak detection valve assembly and control module in accordance with an embodiment of the invention; 
     FIG. 2 is a schematic drawing of a leak detection system incorporating the valve assembly of FIG. 1; 
     FIG. 3 is a top view of the valve assembly; 
     FIG. 4 is a front view of the valve assembly; 
     FIG. 5 is a vertical cross sectional view taken along line  5 — 5  in FIG. 3; 
     FIG. 6 is a vertical cross sectional view taken along line  6 — 6  in FIG. 4; 
     FIG. 7 is a horizontal cross sectional view taken along line  7 — 7  in FIG. 4; 
     FIG. 8 is a horizontal cross sectional view taken along line  8 — 8  in FIG. 4; 
     FIG. 9 is a fragmentary cross sectional view of a poppet valve assembly; 
     FIG. 10 is a schematic diagram of the leak detection system; 
     FIG. 11 is a truth table for the leak detection system; and 
     FIG. 12 is a schematic diagram for the control system for the leak detection system. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings for the purpose of describing the preferred embodiment and not for limiting same, FIGS. 1 and 2 illustrate a leak detection system  10  for determining the pressure integrity of components when subjected to pressure conditions during a test period. The leak detection system  10  comprises a valve assembly  12  and a control module  14  operatively coupled with a flow sensor  16  and pressure sensor  18 . As hereinafter described in detail, the leak detector  10  is operative for testing the fluid integrity of test parts to determine is leakage standards are being achieved. 
     Referring additionally to FIG. 10, the valve assembly  12  is fluidly connected with a low pressure source  20  along line  22 , a high pressure source  24  along line  26 , a test unit  28  for testing such parts along line  30 , and an exhaust  32  along line  34 . Supplemental valves may be disposed in the lines for controlling flow therethrough. 
     The control module  14  comprises a pilot valve assembly  36  including pilot valves  40 ,  42 ,  44 , and  46  fluidly connected with a high pressure valve unit  50 , a low pressure valve unit  52 , an exhaust valve unit  54  and an isolation valve unit  56  along lines  60 ,  62 ,  64  and  66 , respectively. The pressure sensor  18  is coupled with the isolation valve unit  56  by line  68 . The flow sensor  16  is connected with the valve units at manifold line  70  and with test part line  30  along line  72 . The pilot valves are connected to pilot pressure  74  by manifold line  76 . The lines and attendant fittings will vary in accordance with the parts undergoing testing and the test conditions. 
     Referring to FIGS. 3 through 8, the valve assembly  12  comprises a valve block  40  housing via ports to be described below a low pressure valve unit  80 , a high pressure valve unit  82 , an exhaust valve unit  84  and an isolation valve unit  86 . 
     As shown in FIGS. 5 and 8, the low pressure valve unit  80  is fluidly connected with line  26  and low pressure source  24  by a low pressure inlet port  90  intersecting with a vertical cross port  92 . The high pressure valve unit  82  is fluidly connected with line  22  and high pressure source  20  by a high pressure inlet port  94  intersecting with a vertical cross port  96 . As shown in FIG. 6, the isolation valve unit  86  is fluidly connected with the line  32  by exhaust port  98  and vertical port  99 . The exhaust valve unit  84  is fluidly connected with line  30  by exhaust port  100 . As shown in FIG. 4, the ports  90 ,  94  and  100  are disposed on the front face  102  of the valve block  12 . The isolation port  98  is disposed on the rear face  104  of the valve block  12 . The ports  100  and  98  are located laterally in a central vertical plane. The ports  90  and  94  are symmetrically disposed on opposite sides of the exhaust port  100  and therebelow. The ports  100 ,  94  and  90  lie in a common horizontal plane. Each of the ports is provided with an outer threaded bore for connection to the associated lines with an appropriate fitting for the fluid application. 
     All of the valve units have a common architecture as representatively shown in FIG.  9 . Therein, a valve unit  110  including a poppet  112  having a valve stem  113  supported by sealing disk  114  for reciprocation between a raised vent position as illustrated and a lowered sealed position in counterbore  115 . The poppet  112  includes a cylindrical valve body  116  carrying O-ring  117  that engages the annular valve seat  118  of counterbore  115  formed coaxially with a vertical port  120 . The outer rim of the sealing disk  114  is supported at the base of a secondary counterbore vertically above bore  115 . The secondary counterbore outwardly terminates at an internally threaded end. A vent cap  124  includes a cylindrical sleeve  125  threadedly received in the threaded bore and a circular base  126  having a threaded center hole  128 . An actuating piston  129  including O-ring  130  is axially slidably carried at the interior surface of the sleeve of the vent cap  124  for movement between a raised position engaging the base  128  and a lowered position engaging the top of the valve stem  113  for moving the poppet  112  to the sealed condition. Angularly disposed vent holes  131  are formed in the sleeve  125  for venting the piston. An air line connected with the pilot pressure line is connected at the center hole  128  for connection with the pilot pressure control system. 
     In typical operation, when pilot pressure is applied in the chamber above the piston  129 , the piston  129  is forced downwardly thereby shifting the poppet  112  to the sealed position. When the pilot pressure is removed and the port  120  is pressurized, the poppet  112  and the piston  129  are driven to the raised, open position. Assist springs may be deployed, particularly in the isolation valve, for providing additional biasing to the open condition. 
     As shown in FIGS. 5 through 8, with respect to the exhaust port  100  and valve unit  84 , a counterbore  138  is formed in the bottom surface of the valve block  40  coaxially therewith. A circular sealing blank  140  is retained at a step in the counterbore  138  by a split retaining ring  142  retained in a corresponding annular groove thus defining a pressure chamber  144 . A C-shaped distribution channel or port  150  extends from the chamber  144  upwardly and intersects the counterbores  115  of valve units  110 . 
     Accordingly, when either of the pressure valve units is pressurized from its source and the pilot control to the piston is interrupted, the air flow in the ports  92 ,  96 ,  99  shifts the poppets to raised, open positions, thereby pressurizing the distribution port  150  and chamber  144  resulting in pressure communication therebetween. Referring to FIGS. 3,  7  and  8 , a pair of vertical ports  160  communicate upstream of the isolation valve unit  84  for connecting one line of the flow sensor  16  and the pressure sensor  18 . A pair of vertical ports  162  communicate on the other side of the isolation valve units  84  with the distribution port  150 . Accordingly, the flow sensor  16  in a conventional manner measures pressure transients on the part under leakage test while the pressure sensor  18  measures pressure conditions on both sides of the isolation valve. 
     The valve unit is operationally connected to an independent test unit whereat parts to be leak tested may be deployed. The test protocol may specify a high pressure test for a defined test period or a low pressure test for a defined test period. Test parts are deemed successful if the leakage under pressure as determined by the flow sensor  16  is below a predetermined threshold. The control system  14  is effective for establishing the appropriate protocol. 
     Referring to FIG. 12, the control system  14  comprises the pilot valve system  250 , a microprocessor  254  coupled with a control panel  255  for defining and conducting the test protocol, test result indicator lights  256  a display screen  257 , for denoting passing or failing of the test connected to a suitable power supply  258 . The microprocessor  254  contains the protocols for the various parts, preferably programmed through an external computer port  260 . The desired protocol is accessed at control panel  255  through menu button  264 , start button  266  and scroll buttons  268 . 
     The operation of the leak detector is illustrated in the truth table of FIG.  11  and taken in conjunction with the schematic of FIG.  2 . 
     A part to be tested in mounted in the test fixture, the control system initialized and the test protocol selected. Thereafter, the test is initiated by actuating the start button  266 . As a first condition, the high and low pressure lines are pressurized with the accompanying pilot valves  40 ,  42  in the normally open positions with the solenoids deenergized. This applies pilot pressure to the associated poppets to close and seal the high pressure and low pressure valve units  50 ,  52 . Correspondingly, the normally closed exhaust pilot is deenergized and the exhaust valve  54  is in the open position. The normally closed isolation pilot is deenergized and the isolation valve unit  56  is in the open position. 
     Thereafter the high pressure pilot  40  is energized, venting the high pressure poppet whereby inlet high pressure air raises the high pressure valve unit  50  to the open position. Concurrently, the exhaust solenoid is energized admitting pilot pressure to the exhaust poppet piston chamber and shifting the exhaust valve unit  54  to the closed position and air flowing past the high pressure poppet pressurizes the exhaust chamber  144  through the distribution channel and past the isolation valve unit  56  to pressurize the test part with high pressure air. Thereafter, the isolation pilot is energized applying pilot pressure to the isolation piston chamber and closing the isolation poppet. Thereafter, the flow sensor  16  monitors pressure transients and through the microprocessor interface denotes pass or fail conditions at the indicator lights. 
     Upon completion of the test, the isolation pilot solenoid is deenergized pressurizing the high pressure piston and sealing the high pressure valve seat, thereby ceasing inlet flow. Concurrently, the isolation and exhaust pilot solenoids are deenergized allowing exhaust chamber and part pressure to shift the exhaust and isolation valves to the open position for completion of the test. In the event of excessive pressure lost at the test part, a light biasing spring may be provided at the isolation poppet to ensure movement to the open position. 
     For testing under low pressure conditions, the exhaust poppet is closed and the low pressure valving sequenced in similar fashion to the high pressure test detailed above. More particularly, a part to be tested in mounted in the test fixture, the control system initialized and the test protocol selected. Thereafter, the test is initiated by actuating the start button  266 . As a first condition, the high and low pressure lines are pressurized with the accompanying pilot valves in the normally open positions with the solenoids deenergized. This applies pilot pressure to the associated poppets to close and seal the later. Correspondingly, the normally closed exhaust pilot is deenergized and the exhaust poppet is in the open position. The normally closed isolation pilot is denergized and the isolation poppet is in the open position. 
     Thereafter the low pressure pilot  42  is energized, venting the low pressure valve whereby inlet low pressure air raises the low pressure valve unit  52  to the open position. Concurrently, the exhaust pilot is energized admitting pilot pressure to the exhaust poppet piston chamber and shifting the exhaust valve unit  54  to the closed position and air flowing past the low pressure poppet pressurizes the exhaust chamber through the distribution channel  150  and past the isolation poppet to pressurize the test part with high pressure air. Thereafter, the isolation pilot solenoid is energized applying pilot pressure to the isolation piston chamber and closing the isolation poppet. Thereafter, the flow sensor monitors pressure transients and through the microprocessor interface denotes pass or fail conditions at the indicator. Upon completion of the test, the isolation pilot is deenergized pressurizing the low pressure piston and sealing the low pressure valve seat, thereby ceasing inlet flow. Concurrently, the isolation and exhaust pilot solenoids are deenergized allow exhaust chamber and part pressure to shift the exhaust and isolation poppets to the open position for completion of the test. 
     Having thus described a presently preferred embodiment of the present invention, it will now be appreciated that the objects of the invention have been fully achieved, and it will be understood by those skilled in the art that many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the sprit and scope of the present invention. The disclosures and description herein are intended to be illustrative and are not in any sense limiting of the invention, which is defined solely in accordance with the following claims.