Abstract:
A pressure relief valve integrally formed with a section of conduit in a closed system for pumping cementitious material eliminates any dead space in the system within which the cementitious material may flow and set, and thus avoids system disassembly for cleaning following use and the possible replacement of clogged system components. The pressure relief valve includes a hollow cylindrical housing disposed on a conduit. First and second elongated linear slots are aligned with the cylindrical housing&#39;s longitudinal axis and are disposed in opposed portions of housing, with one slot in flow communication with the conduit. A cylindrical drum having a third elongated linear slot disposed within the cylindrical housing is freely rotatable therein. A handle attached to one end of the drum allows for manual rotation of the drum for aligning the three slots permitting the discharge of cementitious material and release of pressure in the system.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to systems for pumping a cementitious material under pressure, and is particularly directed to a hand-operated valve for safely releasing the pressure in a closed pumping system for cementitious materials. 
     BACKGROUND OF THE INVENTION 
     There are various types of reciprocating pumps used for pumping cementitious materials. A common form that these types of pumps take is that of a ball valve pump; that is, the flow of material through the pump is controlled by an inlet (suction) valve and a discharge valve, each of which consists of a ball and a seat. Thus, on the suction stroke the inlet ball unseats, allowing material to enter the pump housing, while the discharge valve is seated, preventing drawback of previously pumped material. On the discharge (extend) stroke, the discharge valve is forced open and the inlet (suction) valve is seated, thus preventing blowback into the hopper. This action is very simple, but very effective. 
     The intended purpose of these pumps is to transport and inject under pressure various cementitious materials ranging from fluid slurries to heavy sanded grouts, such as cement slurries, sanded cement mixes, bentonite mixes (with or without sand), repair mortars, high strength non-shrink grouts and self-leveling products. Common characteristics of these materials are that they are often fluid or semi-fluid, have a relatively high specific gravity and are often granular in composition. When the material is moving freely out of the pump and through hoses, the material generally maintains its integrity. However, under pressure, and particularly if the linear velocity is reduced, the materials tend to settle out of suspension and agglomerate within the hose and the discharge portion of the pump. 
     When this occurs, the pressure within the entire discharge system can increase to the maximum pump capacity. Due to the ball valve design, there is no internal means to relieve this pressure buildup. Therefore, the operator will customarily actuate a manually operated pressure dump valve to relieve system pressure so the hoses can safely be disconnected and cleaned. Unfortunately, due to the geometry of these types of valves, there is usually a considerable distance between the flow line and the actual valve mechanism, and often this conduit becomes plugged with material, rendering the valve useless and frequently necessitating its replacement. 
     Referring to  FIGS. 1 and 2 , there are show sectional views of a prior art pressure relief valve  120  in the closed and open positions, respectively. The pressure relief valve  120  is connected to a T-connector  122  by means of a fluid connector  126 . Cementitious material is displaced in either direction along axis X-X′ under pressure within a conduit (not shown for simplicity) to which the T-connector  122  is coupled. Connector  126  may be of conventional design such as of the threaded, pinned or U-clip type. Pressure relief valve  120  includes a housing  128  having a cylindrical expanded portion through which extends a cylindrical slot, or opening,  128   a . Disposed within the cylindrical slot  128   a  and free to rotate therein is a cylindrical insert  130 . Cylindrical insert  130  includes an elongated, linear slot  130   a  extending along a portion of the length of the cylindrical insert. Attached to one end of the cylindrical insert  130  by conventional means such as a threaded member  134  in the form of a screw is a handle  132 . Disposed on the distal end of the valve housing  128  is a discharge end  136  of the pressure relief valve  120 . Rotation of the handle  132  in the direction of arrow  140  shown in  FIG. 1  causes counterclockwise rotation of the valve&#39;s cylindrical insert  130 . 90° degree rotation of handle  132  from its orientation shown in  FIG. 1  results in a corresponding 90° rotation of the valve&#39;s cylindrical insert  130  so that its elongated, linear slot  130   a  is aligned with the lengthwise axis Y-Y′ of the pressure relief valve&#39;s housing  128  as shown in the sectional view of  FIG. 2 . In this position, the cementitious material flowing under pressure within T-connector  122  is discharged via the discharge end  136  of the pressure relief valve  120  so as to reduce the pressure within the conduit. As discussed above, one of the problems with this arrangement is the dead space  138  disposed between the conduit-connected portion of the T-connector  122  and the pressure relief valve  120 . This dead space  138  disposed within the T-connector  122  and a portion of the pressure relief valve  120  is shown in  FIG. 1  as having a length “Z”. It is within this dead space  138  that the cementitious material tends to collect and set, or harden, when the cementitious material is displaced through the conduit and T-connector  122  combination with the pressure relief valve  120  in the closed position as shown in  FIG. 1 . This situation makes cleaning of the grout pumping system after use very difficult and may even necessitate replacement of the T-connector  122  and pressure relief valve  120  combination. 
     The present invention avoids this problem encountered in the prior art by positioning the active part of the valve directly in the flow line to eliminate any buildup of the cementitious material between the flow line and the valve, thus providing a positively acting valve capable of relieving system pressure and preventing plugging of the flow line and valve combination by the pumped material. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide for the quick and safe discharge of pressure in a closed system for the pumping of cementitious materials. 
     It is another object of the present invention to provide a pressure relief valve for a closed system for pumping cementitious materials which avoids problems associated with the quick setting of the material during reduced pumping speed operation or following the termination of pumping. 
     It is a further object of the present invention to provide a hand-operated valve for quickly and safely discharging the pressure in a closed system within which a quick setting material is pumped which eliminates dead space in the system into which the material could flow and set, necessitating disassembly of the system for cleaning and possible replacement of components within which the material has set. 
     Yet another object of the present invention is to provide a hand-operator pressure relief valve for use in a closed system within which a permanent setting-type of material flows which is quickly and easily operated, of rugged and highly reliable design, low in cost and comprised of a minimum number of moving parts. 
     A still further object of the present invention is to allow for the quick and safe release of excessive pressure within a closed system for pumping cementitious material and thus reduce the possibility of injury to workers operating the pumping system. 
     The present invention contemplates a system for displacing a cementitious material comprising: a conduit; a hopper containing cementitious material and coupled to the conduit for discharging cementitious material into the conduit; a pump connected to the conduit on a first side of the hopper for displacing the cementitious material under pressure away from the hopper and toward a discharge end of the conduit; and a pressure relief valve directly attached to the conduit intermediate the hopper and the discharge end of the conduit, wherein there is no dead space between the conduit and the relief valve in which cementitious material can collect and set so as to clog the relief valve and render the pressure relief valve unuseable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The appended claims set forth those novel features which characterize the invention. However, the invention itself, as well as further objects and advantages thereof, will best be understood by reference to the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, where like reference characters identify like elements throughout the various figures, in which: 
         FIGS. 1 and 2  are longitudinal sectional views of the combination of a T-connector and prior art pressure relief valve shown respectively in the closed and open positions; 
         FIG. 3  is an exploded side plan view of a cementitious material pumping system incorporating a pressure relief valve in accordance with the present invention; 
         FIGS. 4   a  and  4   b  are transverse sectional views of a pressure relief valve in accordance with the principles of the present invention shown respectively in the open and closed positions; and 
         FIGS. 5   a  and  5   b  are longitudinal sectional views of the pressure relief valve of the present invention shown respectively in the open and closed positions. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 3 , there is shown a side elevation view in exploded form of a cementitious material pumping system  10  in which the pressure relief valve  90  of the present invention is intended for use. In the following description, the term “cementitious material” is intended to include various materials also sometimes referred to as grout, mortar or finishing plaster. The inventive pressure relief valve  90  is not limited to use within the cementitious material pumping system  10  shown in  FIG. 3 , but has application in virtually any type of high pressure pumping system for use with cementitious materials. 
     The cementitious material pumping system  10  includes an air cylinder  12  coupled to a source of air under pressure, i.e., a compressor (which is not shown for simplicity), by means of an air coupling  14 , an air valve  16 , an air filter  18  and a lubricator  20 . A rear cylinder bracket  26  is coupled by means of a rear mount nut  24  to the air cylinder  12  adjacent to where the lubricator  20  is also connected to the air cylinder. Air under pressure is provided to a shuttle valve assembly  22  mounted to one end of the air cylinder  12 . Shuttle valve assembly  22  alternately routes air under pressure via first and second air hoses  30   a  and  30   b  and front and rear air valves  34   a  and  34   b  to opposed ends of the air cylinder  12  for displacing a piston (also not shown) within the air cylinder in alternating directions in a reciprocating manner. A 90° brass elbow coupler  32  connects the shuttle valve assembly  22  to the rear air valve  34   b . A muffler  23  is connected to the shuttle valve assembly  22  to reduce the noise generated during operation of the pumping system  10 . Connected to a second, opposed end of the air cylinder  12  is a front cylinder bracket  28  which, in combination with the rear cylinder bracket  26 , is used for mounting the air cylinder to a fixed support base. 
     Also attached to the second end of the air cylinder  12  by means of a sleeve coupling  36  is a piston assembly  38 . Piston assembly  38  has an outer housing within which are disposed a machine rod coupling  40 , a pair of backiner plates  44 , a pair of piston cups  46 , a spacer plate  48 , and a piston bolt  42 . Piston assembly  38  is driven in a reciprocating manner by the bi-directional movement of air cylinder  12 . Piston assembly  38  is coupled at a first end by means of the sleeve coupling  36  to the air cylinder, while a second, opposed end of the piston assembly is coupled to a first end of a cylindrical sleeve  50 . A second, opposed end of the cylindrical sleeve  50  is coupled by means of the combination of a first coupling gasket  52  and a first coupling  56  to a first end of a tee assembly  60 . A support bracket  62  is attached to the tee assembly  60  for securely mounting the tee assembly to a support structure. 
     Attached to an upper portion of the tee assembly  60  by means of the combination of a first ball seat O-ring  70 , a second coupling gasket  68  and a second coupling  66  is a hopper  64  having an inverted frusto-conical, or tapered, shape. Cementitious material is deposited in hopper  64  and flows into the tee assembly  60  for displacement by means of the combination of the air cylinder  12  and piston assembly  38 . A first ball  74  moveably disposed in a first ball seat  75  attached between hopper  64  and tee assembly  60  regulates the flow of cementitious material from the hopper into the tee assembly as described in detail below. 
     Cementitious material deposited from hopper  64  into the tee assembly  60  is displaced by means of the combination of air cylinder  12  and piston assembly  38  through the combination of a second ball seat O-ring  72 , a third coupling gasket  54  and a third coupling  58  to a second ball  76  and second ball seat  77  combination. The combination of the second ball  76  and second ball seat  77  is coupled to a pressure relief valve  90  in accordance with the present invention. The inventive pressure relief valve  90  is coupled to a fluid discharge coupling  84  by means of the combination of a fourth coupling  80  and a reducer  82 . Attached to the fluid discharge coupling  84  is a gasket  86  for connecting the cementitious material pumping system  10  to a conduit (not shown) for carrying the cementitious material to a desired location. 
     The cementitious material pumping system  10  operates in the following manner in displacing the cementitious material through the fluid discharge coupling  84  to a location where the cementitious material is to be used. As viewed in  FIG. 3 , rightward displacement of the piston assembly  38  under the influence of the air cylinder  12  causes the second ball  76  to be displaced rightwardly within the second ball seat  77  so as to prevent the flow of cementitious material through the fluid discharge coupling  84 . With the rightward displacement of the piston assembly  38  under the influence of the air cylinder  12 , the first ball  74  is displaced downwardly within the first ball seat  75  allowing cementitious material to drop from the hopper  64  into the tee assembly  63 . Air cylinder  12  then displaces the piston assembly  38  in a leftward direction as viewed in  FIG. 3  causing the first ball  74  to be displaced upwardly within the first ball seat  75  so as to prevent additional cementitious material from dropping into the tee connector  60 , while urging cementitious material in a leftward direction through the tee assembly. The cementitious material displaces the second ball  76  leftward within the second ball seat  77  so as to open this valve. This allows cementitious material to be discharged from the pumping system  10  via fluid discharge coupling  84 . 
     With cementitious material deposited within the tee assembly  60 , the reciprocating action of the air cylinder  12  then causes the leftward displacement of the piston assembly  38  so as to displace the second ball  76  in a leftward direction in the second ball seat  77  and also causes the upward displacement of the first ball  74  within the first ball seat  75 . This action causes the cementitious material within the tee assembly  60  to flow in a leftward direction toward and out of the fluid discharge coupling  84 , while preventing the backflow of the cementitious material into the hopper  64 . During the discharge process, the cementitious material flows through the pressure relief valve  90  of the present invention which is described in detail in the following paragraphs. 
     Referring to  FIGS. 4   a  and  4   b , there are respectively shown transverse sectional views of the pressure relief valve  90  of the present invention in the open and closed positions.  FIGS. 5   a  and  5   b  are longitudinal sectional views respectively showing the pressure relief valve  90  of the present invention in the open and closed positions. Pressure relief valve  90  is integrally formed with, or mounted on, a hollow, cylindrically shaped conduit section  92 . Pressure relief valve  90  includes a generally cylindrical housing  96  having its longitudinal axis aligned generally transverse to the longitudinal axis of the conduit section  92 . Cementitious material is directed along the length of the valve&#39;s conduit section  92  either rightward or leftward as viewed in  FIGS. 5   a  and  5   b  by the piston/cylinder combination described above. An elongated aperture  92   a  is provided in the lateral wall of the conduit section  92  to provide a flow channel between the inner portion of the conduit section  92  and the generally cylindrical slot  96   a  disposed within and extending substantially the length of the generally cylindrical housing  96 . Also disposed in housing  96  in facing relation to elongated aperture  92   a  in conduit section  92  is an elongated aperture  96   b . Disposed within the generally cylindrical slot  96   a  of housing  96  is a cylindrical member  98  which is free to rotate within the cylindrical housing. Cylindrical member  98  includes an elongated, linear slot  98   a  extending substantially the length of the cylindrical member and disposed between opposed lateral portions of the cylindrical member. When the cylindrical member&#39;s slot  98   a  is aligned with aperture  92   a  in conduit  92  and slot  96   b  in cylindrical housing  96 , air under pressure and cementitious material are discharged from the conduit to release the pressure in the conduit. When slot  98   a  is not aligned with aperture  92   a  and slot  96   b , the cementitious material is maintained under pressure within conduit  92  during pumping. One end of cylindrical member  98  is provided with a threaded extension shaft  104 . Attached to the cylindrical member&#39;s threaded extension shaft  104  by means of a nut  102  is a washer  106  for securely maintaining the cylindrical member  98  within the cylindrical slot  96   a  of housing  96 . Attached to a second opposed end of the cylindrical member  98  is a handle  100 . By grasping the handle  100 , cylindrical member  98  may be rotationally displaced within the slot  96   a  of housing  96  between an open position as shown in  FIGS. 4   a  and  5   a , and a closed position as shown in  FIGS. 4   b  and  5   b . In the open position, air under pressure and cementitious material are free to flow through the pressure relief valve  90  and be discharged from the conduit section  92 . With the pressure release valve  90  in the closed position, cementitious material within a conduit of the pumping system is displaced toward the discharge end of the conduit to be used where intended. As shown in the sectional views of  FIGS. 4   a  and  4   b , the outer surface of cylindrical member  98  and slot  96   a  within housing  96  are tapered in a complementary manner so as to provide leak-proof sealing engagement between these two valve components. The inventive pressure relief valve  90  may be of similar composition to that of the conduit in the cementitious material pumping system, with the pressure relief valve preferably comprised of a hard metal or a high strength plastic. The valve&#39;s conduit section  92  may be connected to adjacent sections of a conduit in the pumping system by conventional means such as threaded engagement, U-shaped connecting pins, exterior clamps, or other conventional conduit coupling arrangement, or the pressure relief valve may be attached directly to or formed integrally with the cementitious material carrying conduit. 
     The essence of the present invention is the immediately adjacent positioning of the pressure relief valve  90  and the cementitious material carrying conduit  92  which eliminates any dead space in both the valve and the conduit within which the cementitious material tends to flow, collect and set. Indeed, in the inventive arrangement, portions of the pressure relief valve and the conduit are arranged in a overlapping, or colocated, manner to eliminate the possibility of any cementitious material residue remaining in the pumping system following its use. 
     While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the relevant arts that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.