Abstract:
A pressure regulating system having a tamper-proof safety feature. A pair of seats are mounted to an annular pipe. A first bleed pipe, with a fixed restriction, extends from an inlet conduit to a first chamber. The first chamber is separated from a second chamber by a second diaphragm. A second bleed pipe extends from the second chamber to an outlet pipe. A bleed off mechanism is sealed within the outlet conduit and includes a compressible bellows. When compressed, which occurs when a predetermined pressure level is attained in the outlet conduit, a third seat is moved out of sealing relation with the outlet conduit and the first chamber. This creates an imbalance of the pressures in the chambers that leads to the pair of seats being moved to seal off apertures in the inlet conduit, thereby inhibiting flow into the outlet conduit.

Description:
FIELD OF THE INVENTION 
   The invention generally relates to pressure regulators, and more particularly to pressure regulators having a safety feature which inhibits tampering. 
   BACKGROUND 
   Some conventionally known pressure regulators operate in a mode of operation known as “fail open”. Such “fail open” regulators include a spring biased against a diaphragm in such a way that failure of the diaphragm (such as through rupture) causes the regulator to remain open allowing an unregulated flow of fluid. Other conventionally known pressure regulators operate in a mode known as “fail closed”, wherein the spring is biased against the diaphragm in such a way that failure of the diaphragm causes the regulator to close, preventing any flow of fluid. Yet other conventionally known pressure regulators are merely operating control valves in a fixed position, such that failure of the regulator does not open or close the regulator. Essentially, all conventional pressure regulators operate by sensing the downstream pressure and controlling the flow of fluid based upon the downstream pressure. Thus, all conventional pressure regulators also utilize a sensor positioned at a downstream location and in communication with the regulator through a sensor transmission line. 
   With reference to  FIG. 1 , a conventional dual port “fail open” type of pressure regulator system  10  is shown having a diaphragm  12 , a spring  14 , a rod  16 , an annular pipe  22 , and first and second seats  38  and  42 . The spring  14  is loaded to exert a force on the diaphragm  12  corresponding to a desired outlet pressure P 2  within an outlet conduit  36 . The rod  16  includes a collar  18  connected to the pipe  22 . While an annular pipe  22  is shown, it should be appreciated that any form of pipe with or without an annulus, including for example, a rod or a piston, may be used. Further, although a dual port regulator system is shown, it should be appreciated that a single port regulator system may be used. 
   The pressure regulator  10  is illustrated in the open position. In operation, the pressure regulator  10  reduces an inlet gas pressure P 1  within an inlet conduit  32  to the outlet gas pressure P 2  by bleeding gas past apertures  40  and  44 . In normal operation, while the outlet gas pressure P 2  is below a certain threshold amount, the diaphragm  12  and the spring  14  exert a biasing force through the rod  16  and the collar  18  onto the annular pipe  22  and the seats  38  and  42 , pushing and maintaining the seats  38  and  42  out of sealing arrangement with the apertures  40  and  44 . 
   Upon the downstream or outlet gas pressure P 2  exceeding a desired level, the pressure regulator  10  closes or restricts the apertures  40  and  44  by moving sealing surfaces  46   a  and  46   b  of, respectively, seats  38  and  42 , into sealing contact with the apertures  40  and  44  of the conduit  32 , thereby closing off the source of P 1 . 
   A disadvantage to the conventional pressure regulator systems, such as the system illustrated in  FIG. 1 , is that such systems could be intentionally tampered with or unintentionally adjusted improperly. For example, if the sensor transmission line were sabotaged, i.e. cut, the pressure regulator system would not be able to determine an increase in the downstream P 2 . Instead, the pressure regulator would read a zero value for the downstream P 2 . In addition, the maximum pressure set point of such systems can be affected by pressure from the environment. Further, pressure regulators are often positioned in underground vaults nearby piping, and in circumstances where flooding of the underground vaults has occurred, increased pressure on the exterior of the chamber holding the diaphragm  12  (from the hydrostatic head of the flooding) counteracts the pressure from the spring  14 , resulting in an improperly functioning diaphragm  12 . In these undesired states, outlet pressures higher than those desired for normal operation are delivered, which has the potential for adverse results. 
   SUMMARY 
   The invention provides a pressure regulating system for regulating pressure in a flow system having an inlet conduit with an inlet pressure and an outlet conduit with an outlet pressure. The pressure regulating system includes a first pressure regulator, that has a first diaphragm, a first rod connected to the first diaphragm, a first spring positioned to exert a force on the first diaphragm and the first rod, a pipe receiving an end of the first rod, and at least one seat mounted on the pipe, each seat being capable of sealing a respective aperture in the inlet conduit. The pressure regulating system further includes a second pressure regulator mounted in a location to inhibit tampering and including a bleed off mechanism mounted within and capable of inhibiting flow to the outlet conduit. 
   The invention also provides a method of inhibiting tampering of a pressure regulating system regulating pressure in a flow system having an inlet conduit with an inlet pressure and an outlet conduit with an outlet pressure. The method includes providing a first pressure regulator and a second pressure regulator. The first pressure regulator includes a first rod connected to a first diaphragm, a first spring positioned to exert a force on the first diaphragm and the first rod, a pipe receiving an end of the first rod, and at least one seat mounted on the pipe, each seat being capable of sealing a respective aperture in the inlet conduit. The second pressure regulator includes a first bleed pipe, a housing, the first bleed pipe extending from the inlet conduit into the housing, and a bleed off mechanism mounted within and capable of inhibiting flow to the outlet conduit. Upon the outlet pressure in the outlet conduit exceeding a predetermined value, the second pressure regulator is enabled to inhibit flow into the outlet conduit. 
   These and other advantages and features of the invention will be more readily understood from the following detailed description of the invention that is provided in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a schematic view of a conventional pressure regulator. 
       FIG. 2  illustrates a schematic view of a pressure regulator system constructed in accordance with an embodiment of the invention. 
       FIG. 3   a  is an enlarged view of the bleed off mechanism shown in circle III of FIG.  2 . 
       FIG. 3   b  is another enlarge view of the bleed off mechanism shown in circle III of FIG.  2 . 
       FIG. 4  is an enlarged partial cross-sectional view the annular pipe of FIG.  2 . 
       FIG. 5  is an enlarged partial cross-sectional view of the first rod and the annular pipe constructed in accordance with another embodiment of the invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   With specific reference to  FIGS. 2-4 , there is shown a pressure regulator system  110  in a working relationship with a system for flowing fluid media that includes an inlet conduit  132  and an outlet conduit  136 . As with the pressure regulator system  10  shown in  FIG. 1 , the pressure regulator system  110  is a dual port type, although it should be appreciated that a single port type may also be utilized. The inlet conduit  132  ends at a closed end  134 . The pressure regulator system  110  includes tamper resistant features. Specifically, the pressure regulator system  110  includes first and second diaphragms  112  and  160 ; first, second and third springs  114 ,  120  and  162 ; first and second rods  116  and  152 ; an annular pipe  122 ; and, first and second seats  138  and  142  (FIG.  2 ). Further, the pressure regulator system  110  includes a bleed off mechanism  164  ( FIGS. 2 ,  3   a ,  3   b ). While an annular pipe  122  is shown, it should be appreciated that any form of pipe with or without an annulus, including for example, a rod or a piston, may be used. 
   The first spring  114  exerts a biasing force F on the first diaphragm  112 , which translates the force to the first rod  116 . At an end of the first rod  116  is positioned a pin  130  ( FIGS. 2 ,  4 ). The first rod  116  extends into a channel  126  of the annular pipe  122 . The annular pipe  122  has a slot  128  through which the pin  130  extends, thereby retaining the first rod  116  within the channel  126  of the annular pipe  122 . The slot  130  should be of sufficient length to allow for a complete stroke of the spring  114 . A collar  118  is positioned at a point on the first rod  116  between the first diaphragm  112  and the pin  130 . 
   The annular pipe  122  has a lip  124 , and the second spring  120  is positioned between the lip and the collar  118 . The biasing force F of the first spring  114  is translated through the first rod  116  and the collar  118  to the second spring  120 , which in turn translates the biasing force onto the annular pipe  122 . The first and second seats  138 ,  142 , which are mounted on the annular pipe  122  are pushed out of sealing arrangement with the inlet conduit  132 . Specifically, with movement of the annular pipe  122  in the direction of the biasing force F, the sealing surface  146   a  of the first seat  138  and the sealing surface  146   b  of the second seat  142  are moved out of contact with, respectively, apertures or ports  140 ,  144  of the inlet conduit  132 , allowing flow from the inlet conduit  132  to continue into and through the outlet conduit  136 . Up to a point, the greater the biasing force F, the greater the movement of the annular pipe  122 , and thus the greater the area of the apertures  140 ,  144  available for flow of the fluid media from the inlet conduit  132  to the outlet conduit  136 . At the point where the biasing force F has caused the pin  130  to move to a lowest portion of a slot  128 , the translation of any greater amount of the force F to the annular pipe  122  and the seats  138 ,  142  is inhibited since the collar  118  cannot further depress the second spring  120  against the lip  124 . 
   Next will be described a tamper resistant pressure safety device of the present invention. The tamper resistant pressure safety device includes a first bleed pipe  148 , a housing  153 , and a bleed off mechanism  164 . The first bleed pipe  148  extends from the inlet conduit  132  to the housing  153 . The housing  153  includes a first chamber  154  separated from a second chamber  156  by a second diaphragm  160 . Specifically, the bleed pipe  148  extends into and feeds the first chamber  154 . A fixed restriction section  150  is located at an end of the first bleed pipe  148  within the first chamber  154 . Since the inlet conduit  132  is in fluid communication with the first chamber  154  through the first bleed pipe  148 , the first chamber is at the inlet pressure P 1 . 
   The second chamber  156  is in fluid communication with the outlet conduit  136  through a second bleed pipe  158 , and thus the second chamber  156  is at the outlet pressure P 2 . A third spring  162  is positioned beneath and exerts a biasing force B against the second diaphragm  160 . The second diaphragm  160  is maintained at an equilibrium. pressure state due to the countervailing forces of the inlet pressure P 1  exerted in the biasing force F direction and the outlet pressure P 2  and the biasing force B exerted by the third spring  162 . A second rod  152  is positioned over the second diaphragm  160  and, as illustrated, the third spring  162 . The third spring  162  exerts a greater force than the second spring  120 . As will be described in greater detail, the second rod  152  is movable due to changes in the relative pressures P 1 , P 2  in the chambers  154 ,  156 . 
   The bleed off mechanism  164 , shown in greater detail in  FIGS. 3   a  and  3   b , is sealed against a wall of the outlet conduit  136  and includes a bellows  166  attached to a bleed valve  168  through a third rod  174 .  FIG. 3   a  shows the bellows  166  in its expanded state, while  FIG. 3   b  shows the bellows in its contracted or compressed state. The bellows  166 , which has a length that is dependent upon temperature, is anchored to the outlet conduit  136  via an anchor  184 , while the bleed valve  168  is anchored to the outlet conduit  136  via an anchor  182 . The bleed valve  168  includes first and second legs  170 ,  172 . The third rod  174  is connected to the first leg  170 . A third seat  178  is connected to the second leg  172  and is movable with respect to a third aperture  180  in the outlet conduit  136 . As shown in  FIG. 3   a , the third seat  178  is lodged in the third aperture  180 , while in  FIG. 3   b  the third seat  178  is no longer in contact with the third aperture  180 . The third rod  174  includes a bimetallic temperature corrector  176  which acts to maintain a distance X constant with varying temperatures by compensating for the temperature-induced change in the temperature-dependent length of the bellows  166 . The distance X extends from the end of the bellows  166  connected to the anchor  184  to any point between the bimetallic temperature corrector  176  and the first leg  170  of the bleed valve  168 . 
   Next will be described the operation of the bleed off mechanism  164 . Upon the occurrence of the outlet pressure P 2  exceeding a predetermined pressure, the bellows  166  is compressed by the outlet pressure P 2 . The compression of the bellows  166  in turn creates a pulling force through the third rod  174  on the bleed valve  168 . The leg  170  of the bleed valve  168  is pulled in the direction of the bellows  166 , thereby unseating the third seat  178  from the aperture  180 . The bimetallic temperature corrector  176  inhibits temperature from affecting the movement of the leg  170  of the bleed valve  168 , thereby ensuring that the movement of the leg  170 , and thus the unseating of the third seat  178 , is based solely on the outlet pressure P 2  exceeding the predetermined limit. 
   With the aperture or port  180  opened, the inlet pressure P 1  is allowed to escape from the first chamber  154  at a rate faster than it enters through the first bleed pipe  148 , due to the fixed restriction  150 . It should be appreciated that the fixed restriction  150  may be any suitable restriction, such as, for example, an orifice or a narrowing internal diameter, i.e. a crimp. As the inlet pressure P 1  decreases in the first chamber  154 , eventually the combination of forces in the second chamber  156  from the outlet pressure P 2  and the third spring  162  push the second diaphragm  160 , and hence the second rod  152 , upwardly. The second rod  152  contacts with and moves the seats  138 ,  142  upwardly, thereby closing off the apertures  140 ,  144 . Through this arrangement, if the outlet pressure P 2  exceeds a certain, predetermined safety limit, the bleed off mechanism  164  can act to shut down the flow into the outlet conduit  136 . Since the bleed off mechanism  164  is sealed within the outlet conduit  136 , it is resistant to tampering, as well as to the vagaries of temperature and operator error. Thus, the bleed off mechanism  164  serves as an independent, tamper-proof regulator of outlet pressure and functions as a second pressure regulator capable of overriding the first pressure regulator. Since the first pressure regulator can be sabotaged, a second pressure regulator with an overriding capacity and which is tamper-proof provides enhanced security for the flow of fluids in pipelines. 
   Next will be described, with reference to  FIG. 5 , a different coupling arrangement between the first rod and the annular pipe. As shown, a first rod  216  includes a ledge  217  with radially inwardly and outwardly projecting sections. An annular pipe  222  is shown with an end  224  closing one end of a space  225 . A pin  231  extends between the first rod  216  and connects to the annular pipe  222 . The pin  231  includes a protrusion  233  at one end of the pin  231  within the first rod  216 . The protrusion  233  is trapped within the first rod  216  by the inwardly projecting sections of the ledge  217 . A collar  237  is positioned on the pin  231  near the protrusion  233 . A second spring  120  is biased between the collar  237  and the end  224  of the annular pipe  222 . The pin  231  is attached to the annular pipe  222 , and thus through this arrangement the spring  120  can be compressed but the first rod  216  and the annular pipe  222  cannot be pulled apart as they are held in a coextensive arrangement by the pin  231 . It should be appreciated that instead of an annular pipe  222  a rod, piston or other type of pipe may be used. 
   In operation, the diaphragm  112  and the first spring  114  exert an inlet pressure P 1  on the first rod  216 , which in turn biases the pin  231 , through the collar  237 , and the second spring  120  toward the annular pipe  222 . The biasing force of the springs  114 ,  120  and the first diaphragm  112  are translated to the annular pipe  222 . 
   While the invention has been described in detail in connection with exemplary embodiments known at the time, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.