# Patent

## Title
Strainer

## Abstract

A conduit has a first end and interior and exterior surfaces extending downstream from the first end. A strainer has a first end and a second end. An upstream portion of the strainer is positioned engaging a projection on the interior surface of the conduit to resist downstream shifting of the strainer. A strainer body extends at least partially downstream of the upstream portion. The apparatus may be used as a strainer/coupler and may be used to filter water in a chiller apparatus.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This is a division of Ser. No. 10/350,634, filed Jan. 24, 2003 now U.S. Pat. No. 6,955,266, the disclosure of which is incorporated by reference herein as if set forth at length.


BACKGROUND OF THE INVENTION
This invention relates to fluid handling, and more particularly to the straining of aqueous heat transfer fluids in refrigeration systems.
Industrial refrigeration is a well developed field. Many systems involve transferring heat to or from an aqueous solution, often essentially water. The heat may be exchanged with a refrigerant passing along in a closed-loop refrigeration cycle. In many systems, the cooled fluid is water which may flow in a closed loop (e.g., for building or industrial cooling) or in an open loop (e.g., for consumption). In water-cooled chillers, the heated fluid is also water. It is advantageous to strain the fluid to prevent clogging of or damage to system components.
BRIEF SUMMARY OF THE INVENTION
One aspect of the invention is an apparatus having a conduit and a strainer. The conduit has a first end, interior and exterior surfaces extending downstream from the first end, and a projection on the interior surface. The strainer has a first end and a second end. An upstream portion of the strainer is positioned to engage the conduit projection to resist downstream shifting of the strainer. A strainer body extends at least partially downstream of the upstream portion.
The apparatus may be used as a coupler for connecting first and second fluid conducting members and extending along an axis between the first end and a second end. The exterior surface proximate the conduit first and second ends may be adapted for connection to the first and second fluid conducting members. Such adaptation may comprise first and second recesses at first and second locations relatively close to the first end and to the second end, respectively. The apparatus may further include first and second clamps for respectively securing the conduit to the first and second fluid conducting members. The first recess may be axially aligned with the projection such as being commonly formed by an annular indentation from the exterior.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view of a chiller system.
FIG. 2 is a partial longitudinal sectional view of a strainer/coupler assembly of the system of FIG. 1.
FIG. 3 is an end view of the strainer/coupler assembly of FIG. 2.
FIG. 4 is a detailed longitudinal sectional view of an upstream end portion the strainer/coupler assembly of FIG. 2.
FIG. 5 is a partial longitudinal sectional view of an alternate strainer/coupler assembly.



Like reference numbers and designations in the various drawings indicate like elements.
DETAILED DESCRIPTION
FIG. 1 shows a chiller system 20. The system includes two heat exchangers: an evaporator (cooler) 21; and a condenser 22. A first flow from a condenser pump 24 passes through the condenser 22 and a second flow from a cooler pump passes through the cooler 21.
The exemplary system is a water-cooled system in which a refrigeration subsystem 30 has a refrigerant flow path that transfers heat to the first flow in the condenser and draws heat from the second flow in the evaporator. The condenser and cooler pump 24 and 26 respectively have outlet conduit assemblies 50 and 52 connecting such pumps to the heat exchanger and inlet conduit assemblies 54 and 56 receiving water from an outside condensing water loop and a chilled water loop (building or industrial process return).
In a exemplary use, the evaporator produces chilled water that may be used, for example, for air conditioning a building or cooling an industrial process. The condenser 22 is coupled to an appropriate external heat rejection system (not shown). Exemplary heat rejection systems may be an open loop cooling tower or a closed loop air-cooled liquid cooler.
To protect the pumps from damage and the heat exchanger from clogging, strainers are advantageously provided in both the condenser and cooler flow path loops. In the exemplary embodiment, both inlet conduit assemblies 54 and 56 have an inventive strainer/coupler assembly 60 joining upstream and downstream conduit sections 62 and 64. Each assembly 60 includes a sleeve 66 and upstream and downstream clamps 68 and coupling the sleeve to the upstream and downstream conduits and 64. In the exemplary embodiment, the conduits 62 and 64 and sleeve 66 are formed of steel pipestock with rolled clamp grooves (described below) near their ends.
FIG. 2 shows further details of the strainer/coupler 60. The sleeve 66 extends from an upstream end 80 to a downstream end 82 and has a central longitudinal axis 500. An exemplary sleeve length is 10 cm. The sleeve has inner (interior) and outer (exterior) surfaces 84 and 86. The upstream and downstream rolled clamp grooves 88 and 90 each define an annular recess 92 in the exterior surface and a rib or annular projection 94 in the interior surface.
Each exemplary clamp 68 and 70 has a split body, the two halves 100 and 102 (FIG. 3) of which are secured to each other via a pair of diametrically opposite threaded bolt/nut assemblies 104. An exemplary clamp body is formed of steel and has a pair of radially inwardly-projecting upstream and downstream lips 110 and 112 (FIG. 2). The upstream lip of the downstream clamp 70 is compressively engaged to the sleeve in the recess 92 of the downstream groove 90. The downstream lip of the downstream clamp 70 is similarly compressively engaged to an upstream recess in the downstream conduit 64 of FIG. 1. Similarly, the downstream lip of the upstream clamp 68 is compressively engaged to the sleeve in the recess of the upstream groove and the upstream lip of the upstream clamp is compressively engaged to a similar recess in the upstream conduit 62 of FIG. 1. Each clamp body carries an elastomeric gasket 120 (FIG. 2) for providing a seal between the sleeve and adjacent the conduit.
The strainer/coupler assembly 60 further includes a strainer 140 acting as means for straining. The exemplary strainer 140 comprises a foraminate element 142 having an upstream interior and a downstream exterior. The exemplary foraminate member is formed as a wire mesh (e.g., of 0.5 mm stainless steel wire in a 15 mesh). The exemplary mesh is rolled into a generally frustoconical configuration and welded along a seam 144 (FIG. 3) to extend from a rim at an upstream end 146 of the element to a downstream end 148. Other forming techniques and other foraminate materials (e.g., perforated members, molded foraminate members, etc.) may be used. An upstream end portion of the foraminate member 142 is secured to a ring 150 captured within the sleeve upstream of the groove 88. In the exemplary embodiment, the ring 150 is formed of sheet metal (e.g., a stainless steel strip 14 mm wide and 1 mm thick) having an interior surface 152 and an exterior surface 154 and upstream and downstream ends or rims 156 and 158 angially engages or, respectively. The downstream rim 158 abuts an upstream-facing end of the rib 94 to prevent downstream movement of the ring and thus the strainer element. The rib 94 forms a projection radially inward or inboard of the recess 92. In the exemplary embodiment, the foraminate member 142 is secured to the ring such as by welding an exterior portion of the foraminate member adjacent the upstream end 146 to the interior surface 152 of the ring.
For installation of the strainer, the strainer may be inserted into the sleeve through the upstream end thereof until the ring 150 seats upstream of the groove 88. In this installed condition, the ring upstream end 156 and foraminate element downstream end 148 define respective upstream and downstream ends of the strainer 140. The length of the foraminate element downstream of the portion secured to the ring is advantageously chosen to provide sufficient straining surface area. In the exemplary embodiment, the downstream end 148 of the foraminate element is located longitudinally between the downstream groove 90 and sleeve downstream end 82. Advantageously, the downstream end 148 is located downstream of the upstream groove 88 and, more advantageously, downstream of a midpoint of the sleeve so as to provide a desired amount of surface area. Advantageously, the downstream end 148 remains upstream of the sleeve downstream end 82 so that the recessing of the strainer may protect the strainer from damage during assembly or disassembly of the inlet conduit assemblies.
For installation of the strainer/coupler, the sleeve is then placed between the adjacent conduits and the clamps are put in place and their bolts/nuts tightened to secure and seal the sleeve ends to the respective conduits. Disassembly for perodic cleaning of the strainer at a cleaning interval or replacement at a replacement interval or as may otherwise be required is by a reverse of this process.
FIG. 5 shows an alternate strainer/coupler assembly 200 having a sleeve 202 and a strainer 204 which, except as described below, may be similar to the sleeve 66 and strainer 140 of the strainer/coupler assembly 60. In the strainer 204, the downstream end 205 of the foraminate element 206 is open. In the exemplary embodiment, this open end is surrounded by a conduit 208 (e.g., a stainless steel tube with an upstream end 210 soldered to the exterior of the foraminate element and a downstream end 212 within a transverse conduit (e.g., a pipe) 220 extending through the sidewall of the sleeve 202. One end 222 of the pipe 220 within the sleeve is closed. The other end 224 is coupled to a valve 226 (e.g., a lever-actuated ball valve threaded into the pipe end). In normal operation, the valve 226 is closed blocking communication through the pipe 220 and, thereby, the downstream end of the strainer 204. The strainer operates as heretofore described. Periodically, however, the strainer may be flushed of solid contaminants by opening the valve 226 and, thereby permitting a flow from the interior of the strainer through the downstream end 205 and tube 212 into the pipe 220 and out an outlet 228 of the valve. This flushing flow may be maintained for an appropriate interval. Despite such flushing, periodically the strainer may still need to be replaced. Strainer replacement is eased by having a nonpermanent engagement between the strainer and the pipe 220. In the exemplary embodiment, the tube 208 is closely fit within an aperture in the pipe sidewall with a clearance similar to or smaller than the mesh opening size of the strainer. This clearance advantageously permits easy removal of an old strainer and insertion of a new strainer without compromising filtration.
One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, details of any particular application may influence attributes of the strainer/coupler assemblies. Accordingly, other embodiments are within the scope of the following claims.

## Claims

1. A system comprising:
a heat exchanger having first and second flows in thermal communication; and
a first pump driving said first flow and having an inlet conduit for receiving the first flow and an outlet conduit coupled to the heat exchanger for delivering the first flow,

wherein the inlet conduit comprises an assembly of:
an upstream conduit;
a downstream conduit, optionally integral with the first pump;
an intermediate conduit;
means for straining the first flow; and
means for coupling the intermediate conduit to the upstream and downstream conduits, the means for straining engaging a radially inward projection on the intermediate conduit to resist downstream movement of the means for straining axially.

2. The system of claim 1 further comprising:
a second pump driving said second flow an having an inlet conduit for receiving the second flow and an outlet conduit coupled to the heat exchanger for delivering the second flow,
wherein the second pump inlet conduit comprises an assembly of:
an upstream conduit;
a downstream conduit, optionally integral with the second pump;
an intermediate conduit;
means for straining the second flow; and
means for coupling the second pump intermediate conduit to the second pump upstream and downstream conduits.

3. A system comprising:
a heat exchanger having first and second flows in thermal communication, the first flow consisting essentially of water; and
a conduit assembly carrying the first flow and comprising:
a first conduit;
a second conduit downstream of the first conduit;
a clamp securing the first conduit to the second conduit and having a first portion engaged to a clamping recess on the second conduit;
a strainer at least partially within the second conduit and retained against downstream movement by axial engagement with an interior projection of the second conduit radially inboard of the recess.

4. The system of claim 3 wherein:
the strainer is entirely within the second conduit;
the first conduit is an upstream conduit;
there is a downstream conduit;
the second conduit is an intermediate conduit; and
a second clamp couples the intermediate conduit to the downstream conduit.

5. The system of claim 3 wherein:
a third conduit extending through a sidewall of the second conduit and has a first portion in fluid communication with a downstream portion of the strainer and a second portion coupled to a valve for selectively establishing communication between the strainer and a destination external to the second conduit.

6. The system of claim 3 wherein the strainer has:
a sheet metal sleeve; and
a strainer body comprising a frustoconical sidewall secured to said sheet metal sleeve and extending downstream of said sheet metal sleeve to an end portion.

7. The system of claim 6 wherein:
the strainer body consists essentially of a wire mesh.

8. The system of claim 3 wherein:
the second flow is aqueous.

9. A system comprising:
a heat exchanger having first and second flows in thermal communication; and
a first pump driving said first flow and having an inlet conduit for receiving the first flow and an outlet conduit coupled to the heat exchanger for delivering the first flow,

wherein the inlet conduit comprises an assembly of:
an upstream conduit;
a downstream conduit, optionally integral with the first pump;
an intermediate conduit formed of steel pipestock with first and second clamp grooves at respective first and second ends;
first and second clamps respectively engaging the first and second clamp grooves and respectively coupling the intermediate conduit to the upstream and downstream conduits; and
a strainer for straining the first flow positioned at least partially within the intermediate conduit wherein the strainer is retained against downstream movement by axial engagement with an interior projection of the intermediate conduit radially inboard of the first clamp groove.

10. The system of claim 9 wherein:
the first flow is aqueous.

11. The system of claim 9 wherein:
the first flow consists essentially of water.

12. The system of claim 9 wherein:
the second flow is aqueous.

13. A system comprising:
a heat exchanger having first and second flows in thermal communication;
a first pump driving said first flow and having an inlet conduit for receiving the first flow and an outlet conduit coupled to the heat exchanger for delivering the first flow,

wherein the inlet conduit comprises an assembly of:
a first conduit;
a second conduit;
a clamp coupling the first conduit to the second conduit and engaged to a first clamp groove of the first conduit; and
a strainer for straining the first flow positioned at least partially within the first conduit and retained against downstream movement by axial engagement with an interior projection of the first conduit radially inboard of the first clamp groove.

14. The system of claim 13 wherein:
the first flow is aqueous.