Abstract:
An in-line water hammer arrester comprises a housing connectable at each end to a piping system, a fluid channel disposed within the housing to permit fluid to flow from the piping system through the housing and back into the piping system, a piston and a pressurized gas chamber. When a pressure spike occurs, the piston is pushed against the pressurized gas chamber allowing an expanded area for water flow until the pressure spike is dissipated and the piston returns to its resting position. When used with flexible hoses and tubing typically found with household appliance water supply lines, the in-line arrester is easily installed by a crimping or clamping type connector and takes up little space.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an in-line device for dampening pressure spikes and reducing “water hammer” noise caused by abrupt pressure changes within a pipe, hose, or flexible tubing when the flow of water is shut-off. 
     2. Description of Related Art 
     Water hammer is a common occurrence when there is a sudden change in pressure in a pipe caused by shutting-off the flow of water through the pipe. Pressure spikes associated with quick shut-off valves can be 5 times or more greater than the normal pressure within the system. These changes in pressure may cause rattling and shaking of the pipes, producing the typical “hammering” noise associated with this problem, although the pressure change may cause damage to the piping system even when there is no hammering noise. The pressure spike can reverberate backward from a valve and cause damage to parts throughout the system, including fittings, valves, backflow preventers, and appliances connected to the piping system. 
     One way of preventing water hammer is by installing a water hammer arrester. These devices typically include a pipe, capped at one end, with a piston and a pressurized air pocket between the piston and the capped end, with the open end of the pipe connected to a pipe in the system just upstream of where a pressure spike may occur or connected at a valve and typically included in a valve outlet box. The arrester is typically installed perpendicular to the system pipe. When a pressure spike occurs, the pressurized water pushes against the piston in the arrester, which moves against the compressed air pocket until the pressure is stabilized and the piston returns to its normal, resting position within the arrester. This dampens the pressure so that it does not reverberate back through the piping system. 
     This type of prior art hammer arrester works well with fixed piping installations, but requires extra room for installation and larger sized outlet boxes to accommodate the arrester. Additionally, it is more difficult to install since it typically involves soldering pipe, compression joints, crimping on to PEX, or other various means of connections. If it becomes necessary to retro-fit a piping system with a hammer arrester, then the difficulty increases since it is more difficult to access piping within walls or to add a hammer arrestor at an existing outlet box. Moreover, this type of design does not work with flexible hoses and tubing typically found on washing machines, dishwashers, and refrigerators/ice makers, even though the valves used with these appliances may cause severe pressure spikes. 
     In-line type arresters are also known, which have advantages over a T-connector style arrester, but these use dampening materials rather than pistons. For example, U.S. Pat. No. 6,672,337 discloses a cushioning diaphragm around a fluid chamber and U.S. Pat. No. 8,307,855 discloses a set of gas-filled balloons within a larger diameter pipe for dampening the pressure spike. A piston is more effective than cushioning materials. 
     SUMMARY OF THE INVENTION 
     The water hammer arrester apparatus disclosed herein may be added to standard and preexisting flexible hoses and tubing typically found on supply lines for washing machines, dishwashers, and refrigerators/ice makers. According to one embodiment of the invention, the water hammer arrester is installed in-line in a flexible hose by crimping or otherwise sealing the water hammer arrestor in the middle of a standard hose. This way a water hammer arrestor installation is as easy as for the average homeowner as installing a standard hose and it can be done without requiring professional assistance. Moreover, the apparatus is relatively small and the diameter is only slightly larger than the typical diameter of flexible hose supply lines for household appliances, so it can easily fit in the same space that housed a standard flexible supply line before installation of the arrester with supply line. With the use of the apparatus according to an embodiment of the invention, it would not be necessary to install arresters in a valve outlet box, which will allow for smaller boxes which are less expensive. 
     According to another embodiment of the invention, the water hammer arrestor comprises a piston and a pressurized gas chamber, similar to prior art devices, but the arrestor is in-line with the system and the water passes through the arrester. This in-line design allows the arrester to be compact and easy to install on existing flexible hoses or tubing. 
     These and other features, objects and advantages of the present invention will become better understood from a consideration of the following detailed description of the preferred embodiments and appended claims in conjunction with the drawings. Although the discussion of the preferred embodiment will focus on use of the apparatus with flexible hoses and tubing, the invention may be used with copper pipe, CPVC pipe, PEX pipe, and other hard surface piping systems with different means of connecting the ends of the apparatus in-line with these pipes, as will be understood by those of ordinary skill in the art. Additionally, the invention may be installed inside an appliance, such as a washing machine or dishwasher, by the manufacturer of the appliance, as will also be understood by those of ordinary skill in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The apparatus of the invention is further described and explained in relation to the following drawings wherein: 
         FIG. 1  is a perspective view of one embodiment of an apparatus according to the invention; 
         FIG. 2  is cross-sectional side elevation view of the apparatus of  FIG. 1  with the piston in its resting position; 
         FIG. 3  is a cross-sectional side elevation view of the apparatus of  FIG. 2  with the piston in fully compressed position; 
         FIG. 4  is cross-sectional side elevation view of the apparatus of  FIG. 1  as connected to a flexible hose. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , one preferred embodiment of an in-line water arrester apparatus  10  is depicted. Apparatus  10  preferably comprises a cylindrical housing  12  having a shoulder  52  at each end, a first end fitting  22 , a second end fitting  30 , and a longitudinal fluid channel  34 . During normal operation of a piping system (including a system using hard pipe material or flexible hoses or tubing), water flows from first fitting  22  (the upstream or rearward end) toward the second fitting  30  (the downstream or front end). Apparatus  10  is installed upstream from a valve that would close and create a pressure spike. Typically, such a valve is part of the appliance with which the arrester is being used. For use with a washing machine, for example, arrester  10  would be installed in the flexible water supply line between the water supply valve (which is usually left in the on position and is not the source of the pressure spike) installed in the outlet box at the wall and the washing machine. Each end fitting  22  and  30  preferably comprises a barbed end  24  and  32  and a neck portion  21  and  31  that extends outwardly beyond shoulder  52 . Alternatively, arrester  10  may be installed inside an appliance, most preferably by the manufacturer of the appliance, near the appliance valve that may cause water hammer. 
     A preferred embodiment of arrester apparatus  10  is depicted in  FIGS. 2 and 3 . Arrester apparatus  10  comprises housing  12 , first end fitting  22 , second end fitting  30 , piston  14 , pressurized gas chamber  20 , and fluid channels  34 ,  28 , and  26 . First end fitting  22  is disposed at the upstream end of housing  12 . First end fitting  22  comprises a cylindrical body  16  having an interior (or downstream) end  40  and a shoulder  41 , a cylindrical neck  21  extending outwardly from shoulder  41 , and barbed end  24 . Shoulder  41  abuts shoulder  52  of housing  12 . Neck  21  extends outwardly (upstream) from housing  12  through aperture  54 . Barbed end  24  is preferably widest near neck  21  and tapers as it extends outwardly from neck  21  to facilitate insertion into a flexible hose, with the widest, barbed portion helping to secure the barbed end  24  from dislodging from the flexible hose. A longitudinal fluid channel  26  extends through barbed end  24  and neck  21 . Another fluid channel  28  is formed on the interior of cylindrical body  16 . Fluid channel  28  has a larger diameter than fluid channel  26 . Fluid, typically water flowing through the piping system, may freely flow from fluid channel  26  to fluid channel  28  when water is flowing through the system. At least one, and preferably at least two, annular recesses  35  are disposed within an exterior surface of a sidewall of body  16 . Disposed within each annular recess  35  is a sealing ring  36 , which frictionally engages an interior wall of housing  12  to secure first end fitting  22  within housing  12  and prevent water from leaking between housing  12  and first end fitting  22 . 
     Piston  14  is preferably substantially cylindrical. At least one, and preferably at least two, annular recesses  56  are disposed within an exterior surface of a sidewall of piston  14 . Additionally, at least one, and preferably at least two, annular recesses  58  are disposed within an interior surface of a sidewall of piston  14 . Disposed within each annular recess  56  is a sealing ring  60 , which provides slidable engagement between piston  14  and an interior wall of housing  12 . Disposed within each annular recess  58  is another sealing ring  38 , which provides slidable engagement between piston  14  and an exterior wall of fluid shaft  62 . Piston  14  may include a channel disposed between annular recesses  56  and  58  to facilitate molding. Sealing rings  60  and  38  prevent water and gas from leaking to or from fluid chamber  28  and pressurized gas chamber  20 . 
     Second end fitting  30  is disposed at the downstream end of housing  12 . Second end fitting  30  comprises a substantially cylindrical body  18  having an interior (or upstream) end  46  and a shoulder  44 , a cylindrical fluid shaft  62 , a cylindrical neck  31  extending outwardly from shoulder  44 , and barbed end  32 . At least one, and preferably at least two, annular recesses  35  are disposed within an exterior surface of a sidewall of body  18  that is adjacent an interior wall of housing  12 . Disposed within each annular recess  35  is a sealing ring  36 , which frictionally engages an interior wall of cylindrical housing  12  to secure second end fitting  30  within housing  12  and prevent gas from leaking out of pressurized chamber  20  between housing  12  and second end fitting  30 . Shoulder  44  abuts shoulder  52  of cylindrical housing  12 . Neck  31  extends outwardly (downstream) from housing  12  through aperture  54 . Barbed end  32  is preferably widest near neck  31  and tapers as it extends outwardly from neck  31  to facilitate insertion into a flexible hose, with the widest, barbed portion helping to secure the barbed end  32  from dislodging from the flexible hose. Fluid shaft  62  extends inwardly (upstream) from neck  31 . An upstream end  45  of fluid shaft  62  extends partially into fluid chamber  28 . An annular chamber  48  is formed between body  18  and fluid shaft  62 . A longitudinal fluid channel  34  extends through barbed end  32 , neck  31 , and fluid shaft  62 . Fluid channels  26 ,  28 , and  34  cooperate to provide a continuous fluid channel through arrester apparatus  10 . Pressurized gas chamber  20  is formed between an interior wall of housing  12 , an exterior wall of fluid shaft  62 , end  43  of piston  14 , and end  46  of body  18 . Pressurized gas chamber  20  should meet the latest edition of ASSE 1010 testing standards to adequately reduce the impact of a pressure spike in the system. Although air is the preferred gas to use in pressurized chamber  20 , other gases, preferably inert gases such as nitrogen, may also be used. 
     Under normal operating conditions, when the pressure in the piping system is stable, piston  14  is in its resting position near first end fitting  22 , as shown in  FIG. 2 . The pressure in pressurized gas chamber  20  is greater than the pressure in the system, which holds piston  14  in the resting position. When a pressure spike occurs, the pressure in the system becomes greater than the pressure in pressurized gas chamber  20 , causing piston  14  to move forward toward second end fitting  30 . Until piston  14  is moved some distance forwardly by the pressure created by a closing valve, part of end  42  of piston  14  abuts end  40  of body  16 . Piston  14  may move forwardly as needed to accommodate the pressure spike. For a severe spike, piston  14  may move forwardly until downstream end  43  abuts end  46  of second end fitting  30 , as shown in  FIG. 3 . Chamber  48  accommodates the gas from chamber  20  when piston  14  is pushed all the way forward. When the piston is pushed forward from its resting position, a fluid chamber  29  forms in the area between an interior wall of housing  12 , end  40 , piston end  42 , and an exterior wall of fluid shaft  62 , allowing a greater volume for the water to fill. As the pressure in the system stabilizes, piston  14  moves back to its resting position, pushing fluid out of fluid chamber  29  and back into fluid channel  28  (and channels  26  and  34 ), and allowing the gas to expand back into pressurized chamber  20 . 
     A preferred embodiment of water hammer arrester apparatus  10 , as installed on a flexible hose, is depicted in  FIG. 4 . Flexible hose  68  connected to a water supply line and an appliance, for example, is cut to expose two open ends. A clamp or crimp-type connector  70  is inserted over each of barbed ends  24  and  32  and abuts a recessed area on shoulder  52  of housing  12  (the recessed area best viewed in  FIG. 1 ). Connector  70  preferably has a hose end  76 , a neck  72 , and a shoulder end  74 . A cut end of hose  68  is inserted into hose end  76  of connector  70  and barbed end  24  is inserted into the cut end of hose  68  inside connector  70 . The other cut end of hose  68  is similarly inserted into hose end  76  of the second connector  70  and barbed end  32  is inserted into the cut end of hose  68  inside the second connector  70 . Each connector  70  is then crimped or clamped to secure hose  68  to arrester apparatus  10 . Any other type of connector suitable for use with flexible hoses or tubing, may be used to connect hose  68  to arrester apparatus  10 . Arrester apparatus  10  may be preassembled with shoulder end  74  of connector  70  attached at both ends of apparatus  10 , two connectors  70  may come pre-packaged with apparatus  10 , or connectors may be purchased separately from apparatus  10 . Arrester apparatus  10  may also be used with copper pipe, CPVC, PEX or other hard piping systems using suitable connectors to connect the arrester to the piping as will be understood by those of ordinary skill in the art. 
     Alternatively, arrester  10  may include threaded or crimping or clamping type connectors pre-attached to or integrally manufactured with either end fittings  22  and  30  and/or housing  12 . Such connectors may include washers or similar fittings to prevent water leakage. Such connectors would mate with similar connectors installed on a flexible hose or tubing or piping with which arrester  10  is to be used. In this alternate configuration, barbed ends  24  and  32  may not be necessary and it may not be necessary for necks  21  and  31  to extend outwardly from housing  12 . As yet another alternative, arrester  10  may be integrated with or pre-attached to a flexible hose, tubing, or a length of pipe for easier installation. For example, the ends of a flexible hose may come with threaded connectors that are ready to attach to the water supply valve and the inlet of a washing machine, with the arrester  10  already in place on the flexible hose so the user need only tighten the connections at the valve and washer inlet, rather than cutting the hose and having to install the arrester with crimp connectors. Those of ordinary skill in the art will understand the modifications that would be needed for such alternate connection configurations. 
     First end fitting  22 , second end fitting  30 , and piston  14  are each preferably unitarily molded as a single part. The preferred materials for first end fitting  22 , second end fitting  30 , and piston  14  are Acetal, but other plastic or metal materials, such as polysulfone, polyphynelsulfone, steel, brass, or other copper alloy, may also be used. Sealing rings  36 ,  38 , and  60  are preferably standard o-rings. Most preferably, sealing rings  38  are smaller in size than sealing rings  36  and  60 , which may be the same size. Additionally, annular recesses  35  on the first end fitting and the second end fitting may be the same size or different sizes, with the sealing rings  36  sized accordingly. Housing  12  is most preferably made of stainless steel, but other materials, such as copper or aluminum or other metals or plastics may also be used. 
     References to front (or forward) and rear (or back) herein generally refer to the direction of water flow, with forward being in the downstream direction. Those of ordinary skill in the art will also appreciate upon reading this specification and the description of preferred embodiments herein that modifications and alterations to the apparatus may be made within the scope of the invention and it is intended that the scope of the invention disclosed herein be limited only by the broadest interpretation of the appended claims to which the inventors are legally entitled.