US2227961A - Valve testing apparatus - Google Patents

Description

Patented Jan. 7, 1941 PATENT OFFICE VALVE TESTING APPARATUS Reed J. Caughey, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application December 1, 1938, Serial No..243,399

6 Claims.

This invention relates to valve controlling apparatus and more specifically to apparatus for testing valves in relatively high pressure fluid conduit systems.

In conduit systems for supplying high pressure elastic fluid to consuming apparatus such as turbines, a stop valve is usually provided for interrupting the flow of elastic fluid in the system in accordance with a predetermined abnormal condition of operation of the consuming apparatus. In many installations such emergency valves are not operated during extended periods of time and during such periods of inoperation sedimentary formations, corrosion, or other abnormalities may cause the valve to stick or render it incapable of instantaneous operation. Means are usually arranged in the valve control system whereby such emergency valves may betested from time to time to ascertain their operating condition. Such testing is usually done by moving the valve to a slightly closed position sufficient to satisfy the inspector that the valve is in working condition, the valve being immediately thereafter restored to the full open position. In certain installations,

because of the relatively high fluid pressure acting upon the upper surface of the valve disk, the valve, if moved slightly too far in testing, may become unbalanced to such an extent that it will be suddenly moved to the fully closed position against the force of the operating mechanism. Before the valve can be restored to its open position, it is necessary to close the control valves to the after connected apparatus 50- that the back pressure may be built up by the opening of the stop valve pilot to the point at which. the main valve disk may be opened by its operating motor. Such unintentional closing of the stop valve is undesirable since the continuity of operation of the. after-connected apparatus is thereby disrupted.

It is an object of this invention to provide a new and improved arrangement for testing the operability of avalve in service.

It is a further object of this invention to provide a new and improved arrangement for testing stop valves in relatively high pressure elastic fluid systems whereby unintentional closing of the valve is precluded.

In accordance with the illustrated embodiment oi the invention, means are provided in conjuncdanger of the valve being accidentally moved to the fully closed position by virtue of faulty ma nipulation of the testing auxiliaries.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto taken in connection with the accompanying drawing.

In the drawing, Fig. 1 is adiagrammatic sketch illustrating one embodiment of my invention, while Fig. 2 is a detailed view showing the pilot valve'of Fig. l in a. second position of adjustment.

Referring to the drawing, I!) is a valve arranged in an elastic fluid system of relatively high pressure, the direction of flow therethrough 15 being represented by the arrow The valve disk I2 may be of any well-known form suitable for use with high fluid pressures. The valve is adapted to be operated to the opened position by means of a fluid motor I3, the piston I4 slidably arranged in cylinder I5. being operatively connected to the valve stem. IS. The valve is normally biased to the closed position by means of a spring I] shown in this instance as being arranged within the motor cylinder above the piston I4. Operating fluid under pressure may be supplied from any suitable source through the conduit l8, the supply thereof to the motor being usually controlled by a control .or, pilot valve l9- and by a trip valve 20 arranged in series as regards the direction of fluid flow through the connecting conduits 2| and 22. The pivot valve It includes a cylinder 23 having spaced apart heads 24 and 25 arranged on the stem 26. The stem is adapted to be operated manually, or otherwise, by a first operating lever 21 pivoted at 28 on the bracket 29. The lower end of the lever 21 is connected by a link 30 to the upper end of the stem 26. The stem is biased upwardly by means of the spring 3| arranged between the upper end of the cylinder and the collar 32 secured onto the stem, the spring being normally held under compression by the toggle arrangement of the lever 2! and link 30 as shown in full line in Fig. 1. In this position, communication is established through the pilot valve between the conduits I8 and 2|. When the pilot valve operating lever 2'! is rotated in a clockwise direction to a position as shown in dotted line, the toggle is broken and the stem will be moved upwardly under the force of spring 3|. As the valve head 25 moves past the port of the connection 2|, fluid will be drained from the cylinder of the motor I3 through the open end 33 of the pilot valve cylinder resulting in the closing of the valve Ill. The trip valve 20 ample, a governor 4| embedded in the turbine shaft 42 may be arranged for tripping the latch ,7

arm 43 upon the occurrence of a predetermined abnormal speed condition. Due to the action of j the spring 39, the valve heads will then be moved to the right shutting off the supply of operating fluid from the conduit 2| and permitting the fluid within the cylinder of the motor l3 to drain-- through the conduit 22 and the open end 44 of the tripping valve.

The arrangement and the operation thereof thus far described is well-known in the prior art. According to my invention, I provide a connection 45 communicating with the cylinder of the motor I3, the inlet port thereof being adapted to be closed by the piston M at a position corresponding to approximately the one-fourth closed position of the valve In. The other end of the connection 45 communicates with the pilot valve I9, the outlet port therein being controlled by the valve head 46 fixed upon the stem 26. In the normal position, as shown, the valve head 46 closes the port of the connection 45. A second operating lever 41 is pivoted as at 48 upon the bracket 49, one end of the lever extending above the collar 32 fixed on the stem 26. For testing the operating condition of the main valve [0,

the lever 41 is rotated about its pivot in the clockwise direction as shown best in Fig. 2 forcing the pilot valve stem downwardly. It will be noted that the link 30 is provided with a longitudinal slot 50 for accommodating the downward movement'of the pilot valve stem. The downward movement of the stem may be limited by means of astop 5| provided on the bracket 49 and adapted to be engaged by the lever 41. With reference to Fig. 2 it will be noted that the limited downward movement of the pilot valve stem slightly uncovers the port of the connection 45 so that fluid is allowed to drain from the cylinder of the motor 13 and escape from the pilot valve through the clearance hole 52 around the stem. Downward movement of the pilot valve stem for uncovering the port 45 does not affect the communication between the operating fluid supply conduit l8 and the conduit 2| so that operating fluid is continuously supplied to the motor [3 during the testing operation. Downward movement of the piston 14 and consequently the closing movement of the valve I0 is limited by the location of the port in the side wall of the cylinder l5 which port is closed upon a predetermined downward movement of the piston l4. When the test is completed, that is, the operating condition of the stop valve ascertained, the testing lever is released whereupon the pilot valve port of the connection 45 will again be closed by the action of the spring 3 I. Fluid pressure within the motor l3 will again build up and restore the main valve to its previous fully opened position.

It is obvious that the exact location of the port of the connection 45 in the cylinder l5 may be varied as desired relative to the valve opened position of the piston M. It is a general practice, however, to provide operating motors for stop valves of such a size as are capable only of opening the valve disk against a maximum pressure drop thereacross of approximately 15%. It is necessary under such conditions, therefore, to so position the port that while testing the stopvalve it will not be moved to such a closed position that the pressure drop thereacross becomes greater than this value. With a pressure dropgreater than this value occurring thereacross, the valve will be forced to the closed position against the opposing force of the operating motor fluid pressure. Roughly, a proper position ofthe port corresponds to approximately the one-fourth closed position of the valve though it is obvious that the most desirable position therefore may be readily calculated by one skilled in the art taking into consideration the various factors involved.

Having described the principle of operation of my invention together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The combination comprising a main valve adapted to be arranged in a relatively high pressure fluid system, a fluid pressure operated motor for normally maintaining said valve in the opened position, means biasing said valve to the closed position, a source of operating fluid connected to said motor, a conduit extending from said motor, a pilot valve in said conduit for draining operating fluid from said motor to cause a closing movement of said main valve, the port of said conduit in said motor being so arranged as to be closed by said motor upon a predetermined partly closing movement of said main valve.

2. The combination comprising a main valve, a fluid pressure motor connected to said valve for normally maintaining said valve in the opened position, spring means normally biasing said valve to the closed position, a conduit for conducting operating fluid to said motor, a control valve arranged in said conduit, means for operating said control valve to shut off the supply of operating fluid to said motor and allowing the escape of fluid therefrom, and means for allowing the escape of fluid from said motor only until said motor is moved an I amount corresponding to a predetermined partly closed position of the main valve.

3. In combination, a stop valve arranged in a relatively high pressure fluid conduit, a motor having a cylinder and a piston slidably arranged in said cylinder, said piston being operably connected to said stop valve, means biasing said piston to the valve closed position, a source of operating fluid, a conduit connecting said source to said motor, a pilot valve arranged in said conduit for controlling the flow of operating fluid to and from said motor, a second conduit communicating with said motor having an opening in the cylinder thereof and so positioned therein that it is closed upon a predetermined valve closing movement by said piston, means provided on said pilot valve for controlling the drainage of operating fluid from said motor cylinder through said second conduit, and means for operating said pilot valve whereby fluid may be drained from said motor to permit only a predetermined valve closing movement thereof While communication is maintained between the source of operating fluid and said motor.

4. Operating apparatus for a stop valve arranged in a relatively high pressure fluid conduit, said apparatus comprising a fluid pressure motor having a cylinder and a piston, means for connecting said piston to said stop valve, means for biasing said motor to the inoperative position, a source of operating fluid for said motor, a conduit for supplying operating fluid from said source to said motor, a pilot valve arranged in said conduit for controlling the flow of operating fluid to and from said motor, a second conduit extending between said motor and said pilot valve, the opening of said second conduit in said motor being so located as to be closed by said piston upon a predetermined movement thereof corresponding to a partly closed movement of said stop valve, said pilot valve being so arranged that operating fluid may be drained from said motor through said second conduit while communication is maintained between the source of operating fluid and said motor.

5. A valve testing arrangement comprising a valve, a fluid pressure operated servo motor having a piston connected to said valve for normally maintaining said valve in the opened position, a source of pressure fluid, conduit means including a control valve for conducting pressure fluid from said source to said motor, a second conduit extending between said motor and said control valve, means for operating said control valve whereby pressure fluid may be drained through said second conduit from said motor and means including the piston of said motor for regulating the drainage of operating fluid through said second conduit so as to preclude the complete closure of said valve.

6. A valve testing arrangement comprising a valve, a fluid pressure operated motor connected to said valve for normally maintaining said valve in the opened position, a source of operating pressure fluid, conduit means including a control valve for conducting operating fluid from said source to said motor, a second conduit having an inlet port in said motor and an outlet port in said control valve, means for operating said control valve to uncover said outlet port to allow drainage of operating fluid from said motor, and means including a portion of said motor for closing said inlet port upon a movement of said motor to a position corresponding to a partly closed position of said valve.

REED J. CAUGHEY.

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