Abstract:
A vent line protection device to protect the vent of a gas regulator from a predetermined water level, including a vertically-oriented housing having an upper portion including vent line connection and an atmospheric vent opening, and a lower portion including a water opening, the vent line connection being adapted to connect to the vent of the gas regulator, and a float disposed inside the housing and being movable in a vertical direction within the housing, an upper end of the float including a seal adapted for scaling off the vent line connection, wherein when the water level is lower than the predetermined level, gas can flow through the housing between the vent line connection and the atmospheric vent opening, and wherein when the water level is at or higher than the predetermined level, the vent line connection is scaled off by the seal of the float.

Description:
BACKGROUND 
       [0001]    Natural gas pressure regulators for residential and commercial gas service are typically mounted with their vent lines near ground level. Sometimes a regulator is mounted outside, but are often it is mounted in a basement where a leak could quickly lead to a dangerous buildup of combustible gas. A supply pipe provides natural gas from a source, often a utility company, to the regulator, and an outlet pipe provides natural gas at a regulated pressure to a consumer. A common type of gas regulator is a self-regulating diaphragm-type regulator which includes a two-part housing separated by a diaphragm that uses spring loading to actuate a valve back and forth to control the regulated gas pressure. The housing on one side of the diaphragm is vented to atmosphere allowing the diaphragm to move back and forth as the regulated pressure is controlled in response to consumer demand. 
         [0002]    In current commercially available natural gas regulators, the regulator vent is usually open to atmosphere. Under normal operation, and normal weather conditions, this is not a problem. However, under extreme weather conditions, such as those that cause flooding, there is a risk that the regulator may be submerged in water and that water will enter into the regulator on one side of the diaphragm, impeding the operation of the regulator and possibly rupturing the diaphragm. The results can be dangerous or even catastrophic, including over-pressuring of natural gas equipment in the consumer facility, as well as fire and explosion due to leaking natural gas. Such incidents occur with frequency in flooded conditions. For example, many natural gas regulators failed in New Orleans due to flooding in the wake of Hurricane Katrina. 
         [0003]    Therefore, there is a need to prevent flooding of a natural gas regulator via the vent, while still allowing the regulator to perform its desired function of controlling the pressure of natural gas provided to a consumer. 
       SUMMARY 
       [0004]    A vent line protection device (which may be alternately referred to herein as a “VLP” device) is provided to protect a vent of a gas regulator from flooding when a level of water external to the regulator is at or higher than a predetermined level. The device includes a generally cylindrical vertically-oriented housing and a generally cylindrical float disposed inside the housing and being movable in a vertical direction within the housing. The housing has an upper portion including a vent line connection and a plurality of atmospheric vent openings circumferentially spaced apart about the housing. The housing also has a lower portion including a water opening. An optional U-shaped tube may connect the housing vent line connection to the gas regulator vent, the U-bend of the U-shaped tube being located vertically above the housing vent line connection and the gas regulator vent. Water entering the housing through the water opening causes the float to rise in the housing. Water exiting the housing through the water opening, combined with gravity acting on the float itself, causes the float to lower. An upper end of the float includes a seal adapted for sealing off the vent line connection. A float stand is mounted to the housing for supporting the float above the water opening. When the water level is lower than the predetermined level, the float is positioned such that gas (including air and/or natural gas) can flow through the housing between the vent line connection and the atmospheric vent opening. When the water level is at or higher than the predetermined level, the float is positioned such that the vent line connection is scaled off by the seal of the float. 
         [0005]    A vent line protection device is provided to protect a vent of a gas regulator from a level of water external to the regulator at or higher than a predetermined level. The device includes a vertically-oriented housing having an upper portion including vent line connection and an atmospheric vent opening, and a lower portion including a water opening. The vent line connection is adapted to connect to the vent of the gas regulator. The device further includes a float disposed inside the housing and being movable in a vertical direction within the housing by water entering the water opening. An upper end of the float includes a seal adapted for sealing off the vent line connection. When the water level is lower than the predetermined level, gas (including air and/or natural gas) can flow through the housing between the vent line connection and the atmospheric vent opening. When the water level is at or higher than the predetermined level, the vent line connection is sealed off by the seal of the float. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The above and other aspects, features and advantages of the vent line protection device described herein will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
           [0007]      FIG. 1  is a schematic showing a vent line protection device attached to a gas regulator, with no water present. 
           [0008]      FIG. 2  is a schematic showing a vent line protection device attached to a gas regulator, with water lifting up the float in the housing toward vent line connection. 
           [0009]      FIG. 3  is a schematic showing a vent line protection device attached to a gas regulator, with water lifting up the float so that an outer seal seals off the vent line connection. 
           [0010]      FIG. 4  is a schematic showing a vent line protection device attached to a gas regulator, with water lifting up the float so that an outer seal is compressed and both the outer seal and an inner seal seal off the vent line connection. 
           [0011]      FIG. 5  is a cross-sectional view showing a vent line protection device attached to a vent tube, with the float in a closed position. 
           [0012]      FIG. 6  is a cross-sectional view showing a vent line protection device attached to a vent tube, with the float in an open position. 
           [0013]      FIG. 7  is a cross-sectional view showing a housing for a float in a vent line protection device. 
           [0014]      FIG. 8  is a cross-sectional view of the housing of  FIG. 7  taken through section line  8 - 8 . 
           [0015]      FIG. 9  is a cross-sectional viewing showing a float for use in a vent line protection device. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    An embodiment of a vent line protection device  10  is shown in  FIG. 1  connected to a natural gas pressure regulator  100  by a vent line  80 . The regulator  100  can be a standard self-regulating diaphragm-type pressure regulator, such as for residential or commercial use, which typically has a regulator housing  102  and includes a diaphragm  104 . The housing  102  on one side of the diaphragm  104  is vented by way of a regulator vent  106  disposed in the housing  102  to allow the housing  102  to breath as the diaphragm  104  moves back and forth to regulate the natural gas pressure supplied to a user. The vent line  80  is connected to the regulator vent  106  to provide a passage for air to flow back and forth between the regulator housing  102  and the outside atmosphere as the regulator  100  controls natural gas pressure based on consumption. The vent line  80  also directs the venting of any natural gas that must be discharged should the diaphragm  104  fail. As used herein, the term “gas” is understood to encompass air, natural gas, and any other gaseous fluid that could be present in the housing  102  of the regulator  100 , including but not limited to other combustible gases that may be substituted for natural gas. The physical structure of the device  10  is described with particular reference to  FIGS. 5-9 , and stages of operation of the device  10  are depicted in  FIGS. 1-4 . 
         [0017]    The device  10  is designed to prevent water from intruding into the regulator  100  due to a flood, such as may be caused by a hurricane. The device  10  allows for full regulator relief of pressure in the housing  102  above the diaphragm  104  through the vent  106 , so that the regulator  100  can operate normally and can be allowed to go into full relief if necessary. The device  10  provides minimal flow restriction and pressure drop when the regulator  100  is in full relief. 
         [0018]    As shown in detail in  FIGS. 5-8 , the device  10  includes a housing  20  having a side wall  22  with a top end  32  and a bottom end  34 . In this one embodiment, the side wall  22  has the geometry of a right circular cylinder, it being understood that other geometries, including but not limited to square, hexagonal, and octagonal cylinders, or generally cylindrical with some irregularity can function equally well. In one embodiment, the housing  20  is made from a cast aluminum alloy to resist corrosion and to minimize weight. 
         [0019]    As installed, the housing  20  is disposed in a substantially vertical orientation with the top end  32  facing substantially upward and the bottom end  34  facing substantially downward. The substantially vertical orientation of the housing  20  allows the device  10  to operate properly under the effects of gravity and buoyancy. The housing wall  22  encloses a cavity  28  in which a float  40  is allowed to move upward and downward, toward the top end  32  and toward the bottom end  34 , respectively, as the water level within the cavity  28  changes. 
         [0020]    The housing  20  comprises an upper portion  36  and a lower portion  38 . A plurality of float guides  30  protrude inwardly into the cavity  28  from the wall  22  in the lower portion  38  of the housing  20 , to guide the float  40  and keep the float generally centered within the cavity  28  as the float  40  moves upward and downward. As shown in greater detail in  FIGS. 7-8 , each float guide  30  includes an elongate protrusion extending substantially vertically along the wall  22  and projecting radially inward therefrom into the cavity  28  in the lower portion  38  of the housing. Spaces  31  between adjacent float guides  30  allow water and/or air to move or flow around the float  40  within the cavity  28 , i.e., between the float  40  and the wall  22 . 
         [0021]    A vent line connection  26  is located at the top end  32  of the housing  20  for connecting to the vent line  80 . The vent line connection  26  provides a passage for gas (including air and/or natural gas) communication between the housing cavity  28  and the regulator vent  106 . In the embodiment depicted in  FIG. 5 , the vent line  80  has an inverted U-shape, with a U-bend  82  being located above both the vent line connection  26  and the regulator vent  106 . The inverted U-shaped vent line  80  provides a pocket of gas in the U-bend  82  that inhibits water intrusion from the housing cavity  28  and helps prevent any water that may intrude into the vent line  80  from reaching the regulator vent  106 . In one embodiment, the height of the U-bend  82  is at least 10 inches above the vent line connection  26 . 
         [0022]    The upper portion  36  of the housing  20  includes one more atmospheric vent openings  24  to provide a communication path for air to flow between the cavity  28  and the external surroundings of the housing  20 . When the vent line connection  26  is open, gas can flow freely from the regulator vent  106  to atmosphere via the vent line  80 , the vent line connection  26 , the cavity  28 , and the vent openings  24 . Accordingly, when the water level is below or above the bottom  34  of the housing, the vent openings  24  provide a pathway to allow air to flow through the housing cavity  28  and into or out of the vent line  80  via the vent line connection  26 . 
         [0023]    The vent openings  24  are located above a predetermined level L on the housing  20  at which rising water causes the float  40  to seal off the vent line connection  26 . In one embodiment, four vent openings  24  are provided equally spaced apart around the periphery of the housing wall  22 . The vent openings  24  can alternatively be located in an upper end wall of the housing  20 . The vent openings  24  may each include a screen  25  to inhibit debris or contaminants from entering the housing through the vent openings  24 . Debris is undesirable because it can compromise the seal between a seal  50  at the top of the float  40  and vent line connection  26 , and can also impair the upward and downward movement of the float  40  within the housing cavity  28 . In one embodiment, a 60-mesh stainless steel screen has been used as the screen  25 . 
         [0024]    The vent openings  24 , in combination with the screens  25 , allow for air to exit the upper portion  36  of the housing  20  as the water level rises, and also allow for both water and air to enter the upper portion  36  of the housing  20 , above the float  40 , as the water level recedes. Water flowing through the vent openings  24  and downward through the housing  20  to the water opening  62  helps the float  40  to release its seal at the vent line connection  26  as the water level recedes. In particular, although in many cases the force of gravity on the float  40  is sufficient to cause the float  40  to drop from the vent line connection  26  as the water level recedes, the soft material of the seal  50  may have a tendency to stick to sealing surfaces  56  and  58 . The action of the downwardly flowing water helps to overcome the tendency of the seal  50  to stick. 
         [0025]    The lower portion  38  of the housing  20  is capped by a base  60  that includes at least one water opening  62  for allowing water to flow into and out of the cavity  28  from below, as the external water level rises or falls, respectively. The base  60  is removably mounted to the housing wall  22  by a conventional mechanism. The base  60  is installed to the housing wall  22  during normal operation, but can be removed for replacement and maintenance of the float  40 , and for cleaning the cavity  28 . The water opening  62  may include a screen  70  to inhibit debris or contaminants from entering the housing through the water opening  62 . In one embodiment, a 40-mesh stainless steel screen has been used as the screen  70 . 
         [0026]    The base  60  includes a float stand  64  for maintaining the float  40  above the bottom  34  of the housing and away from the water opening  62  in the base  60 . The float stand  64  includes a plurality of legs  65  supporting one or more baffles  66 . The baffles  66  slow the flow of water into the housing cavity  28  and are effective at trapping or catching any debris that enters the water opening  62 . In the embodiment depicted in  FIGS. 5 and 6 , the float stand  64  includes two baffles  66   a ,  66   b  offset from each other by the legs  65  in both the lateral and the vertical directions to create a tortuous path for water entering the cavity  28  from the water opening  62 . Any number of baffles  66  may be used. As shown, the baffles  66   a ,  66   b  each have a curved edge conforming to the shape of the housing wall  22  and a straight edge around which water can flow, but innumerable baffles shapes can be created to accomplish the desired purpose. Alternatively, larger mesh screens can be used in place of, or in combination with, baffles. 
         [0027]    Testing was performed in an embodiment including a screen  70  across the water opening  62  in combination with a float stand  64  having two staggered baffles  66   a ,  66   b , as shown. This combination of components was found to be extremely effective at trapping debris that could otherwise impair operation of the float  40  and the sealing off of the vent line connection  26 . 
         [0028]    The float  40  is constructed to have a specific gravity of less than 1, so that it is buoyant or floatable in water. In the embodiment shown in  FIG. 9 , the float  40  is hollow and includes a shell  42  enclosing a cavity  46 . In one embodiment, the float shell  42  can be made from an upper half  42   a  and a lower half  42   b  bonded together in a watertight seal. The float has a bottom end  44  and a top end  48 . The seal  50  is located at the top end  48 . In one embodiment, the float  40  is made from a molded polyethylene material (such as ultra high molecular weight polyethylene, UHMWPE) which is durable, abrasion resistant, and self-lubricating. 
         [0029]    In one embodiment, the float  40  is generally cylindrical in shape, it being understood that a float  40  of another symmetric geometry, including square, hexagonal, and octagonal, could function equally well in the device  10 , including when the cavity  28  in the housing  20  is generally cylindrical, square, hexagonal, or octagonal. The location and number of float guides  30  are selected to correspond to the geometry of the float  40  and the geometry of the housing wall  22 . In non-limiting examples, three float guides  30  equally spaced around the internal circumference of the cavity  28  can guide a round or hexagonal float  40 , and four equally-spaced float guides  30  can guide a round, square, or octagonal float  40 . 
         [0030]    The seal  50  at the top end  48  of the float  40  includes an inner seal  52  and an outer seal  54  surrounding the inner seal  52  and extending upwardly with respect to the inner seal  52 . In one embodiment, as depicted in  FIG. 8 , the seal  50  is in the form of a boot that is made removable from the top end  48  of the float  40  to facilitate maintenance and replacement. In one embodiment, the seal  50  is made from a fluorosilicone material that is both durable and resilient. The flexible material of the seal  50  enables the inner seal  52  to form a positive seal and also enables the outer seal  54  to flex as the float  40  moves upward and the seal  50  begins to contact the housing  20  surrounding the vent line opening  26 . 
         [0031]    An annular raised sealing surface  56  is located in the upper portion  36  of the housing  20  surrounding the vent line opening  26 , and an annular recessed sealing surface  58  surrounds the raised sealing surface  56 . As the float  40  rises in the cavity  28 , buoyed by water entering through the water opening  62  in the base  60 , the movement of the float  40  is unencumbered until the float  40  encounters resistance as the outer seal  54  contacts and begins to seal with the recessed sealing surface  58 . As the float  40  continues to rise slightly, the outer seal  54  is compressed until the inner seal  52  contacts and begins to seal with the raised sealing surface  56 . In operation of the device  10 , the inner seal  52  provides a leak-free seal when the float  40  is pressed up against the raised sealing surface  56  surrounding the vent line connection  26 , while the outer seal  54  helps to center the float  40  and provides a backup seal against the recessed sealing surface  58 . 
         [0032]    When gas pressure accumulates in the vent tube  80 , the float  40  may be pushed slightly downward, lifting the inner seal  52  out of contact with the raised sealing surface  56 . In this circumstance, the outer seal  54  maintains a leak-free seal while allowing gas to escape from the vent tube  80 . One or more gas bubbles can exit the vent tube  80  through the vent line connection  26  by squeezing between the outer seal  54  and the recessed sealing surface  58 , while the outer seal  54  substantially prevents water from entering through the vent line connection  26  into the vent tube  80 . The exiting of a gas bubble relieves excess pressure above the float  40  and allows the float  40  to move upward almost instantaneously once gas pressure is relieved, such that by the time the outer seal  54  is flexing to allow a gas bubble to escape, the buoyancy of the float  40  almost immediately returns the inner seal  52  into contact with the raised sealing surface  56 . 
         [0033]      FIGS. 1-4  depict schematics of the device  10  at various stages of operation, and  FIG. 5  depicts an enlarged view of the device  10 . In  FIG. 1 , the device  10  is shown in a normal, non-flooded operating state. In this state, the water level external to the housing  20  is below the bottom  34  of the housing (and is typically zero), well below the predetermined level L at which the seal  50  first begins to seal off the vent line connection  26 . The level L is indicated in the figures as the threshold external water level that will cause the float  40  to rise enough to cause the outer seal  54  to initiate a seal with the recessed sealing surface  58 . In non-flooded use of the device  10 , the float  40  is at rest on the float stand  64  of the base  60  under the force of gravity. The vent line opening  26  is open so that gas can freely flow to and from the regulator vent  106  via the vent tube  80  and into and through the cavity  28  via the vent line opening  26  and the atmospheric vent openings  24 . 
         [0034]    In  FIG. 2 , the device  10  is shown in a state in which the water level is rising but is below the level L required to make an initial seal. Because the float  40  is hollow, it is buoyant in water. The float  40  may also be made from a material having a specific gravity less than 1, making it further buoyant in water. The rising water level lifts the float  40  off the float stand  64  but is not sufficient to lift the float high enough for the seal  50  to seal off the vent line connection  26 . 
         [0035]    In  FIG. 3 , the device  10  is shown in a state in which the water level has risen to be approximately equal to the level L required to make an initial seal. At this water level, the outer seal  54  contacts the recessed sealing surface  58  to seal off the vent line connection  26 , but the inner seal  52  has not yet contacted the raised sealing surface  56 . The combination of the outer seal  54  and the recessed sealing surface  58  serves to center and align the seal  50  about the vent line connection  26 , while the float guides  30  continue to keep the float  40  centered in the cavity  28 . If gas pressure (e.g., the pressure of air and/or natural gas) increases in the vent line  80  such that gas needs to escape from the vent line  80 , the excess pressure causes the outer seal  54  to flex slightly until the gas forces its way out between the outer seal  54  and the recessed sealing surface  58 , at which point the outer seal  54  immediately returns to contact with the recessed sealing surface  58  to reestablish the seal. 
         [0036]    In  FIG. 4 , the device  10  is shown in a state in which the water level has risen to be above the level L required to make an initial seal. Such a level can include a situation in which the device  10 , including the atmospheric vent openings  24 , is completely submerged. At this water level, the float  40  has risen to compress the outer seal  54  against the recessed sealing surface  58  and to force the inner seal  52  into sealing contact with the raised sealing surface  56 . The interface between the inner seal  52  and the raised sealing surface  56 , which is backed up by the interface between the outer seal  54  and the recessed sealing surface  58 , creates a positive seal sufficient to prevent water intrusion into the vent line  80  even under completely flooded conditions when the entire device  10  is submerged in water. Indeed, as the water level rises higher, the sealing pressure between the inner seal  52  and the raised sealing surface  56  increases. 
         [0037]    In the flooded condition, if gas pressure increases in the vent line  80  such that gas needs to escape from the vent line  80 , the gas pressure increases until it balances the buoyancy force imposed on the seal  50  by the float  40 . The inner seal  52  is forced slightly away from the raised sealing surface  56 , and then the excess pressure causes the outer seal  54  to flex slightly so that one or more gas bubbles can slip out between the outer seal  54  and the recessed sealing surface  58 . Almost immediately, the release of the excess gas pressure causes the outer seal  54  to return to contact with the recessed sealing surface  58 , reestablishing the sealing off of the vent line connection  26 , and the float  40  is buoyed upward so that the inner seal  52  reestablishes sealing contact with the raised sealing surface  56 . Consequently, no water, or at most an inconsequential amount of water, is able to get past the outer seal  54  into the space between the outer seal  54  and the inner seal  52 , or into the vent line connection  26 . 
         [0038]    Any gas bubbles escaping into the upper portion  36  of the housing can be vented via the atmospheric vent openings  24 , even if the openings  24  are submerged. If the atmospheric vent openings  24  are somewhat below the top  32  of the housing  20  a small amount of vented gas will accumulate in the housing  20  before being released. 
         [0039]    When the water level recedes, the device  10  continues to allow the gas regulator  100  to operate normally. In particular, when the water level decreases from higher than the level L to lower than the level L, the float  40  drops with the water level. The inner seal  52  first breaks contact with the raised sealing surface  56  and the outer seal  54  then breaks contact with the recessed sealing surface  58 , thus opening the vent line opening  26  and exposing the vent tube  80  to atmospheric pressure. As the water level continues to recede; the float  40  drops with the water level until the float  40  again rests on the float stand  64 . 
         [0040]    An exemplary embodiment of the device  10  has been manufactured and tested for compliance with 49 C.F.R. §192, subpart H, which relates to Transportation of Natural Gas and Other Gases: Customer Meters, Service Regulators, and Service Lines. The testing was done in conformance with the procedures of ANSI B109.4-1998, 5.3.3-5.3.7 and 5.3.12, which applies to self-operated diaphragm-type natural gas service regulators. 
         [0041]    The foregoing describes the vent line protection device in terms of embodiments foreseen by the inventors for which an enabling description was available, notwithstanding that insubstantial modifications of the device, not presently foreseen, may nonetheless represent equivalents thereto.