US3640303A

US3640303A - Slide valve for high-viscosity pumps

Info

Publication number: US3640303A
Application number: US8381A
Authority: US
Inventors: Cornelis Verheul
Original assignee: Individual
Current assignee: Friedrich Wilhelm Schwing GmbH
Priority date: 1969-02-05
Filing date: 1970-02-03
Publication date: 1972-02-08
Anticipated expiration: 1989-02-08
Also published as: NL142763B; ES376161A1; GB1229764A; AT296033B; CH503198A; DE1905706C2; FR2033928A5; NL7001483A; PL80445B1; JPS4820811B1; BE745435A; CS177027B2; DE1905706B1

Abstract

A slide valve for dense or viscous materials, e.g. concrete, has a slide element connected to a piston rod which extends out of the valve housing through a seal and carries a piston received in a cylinder which is clamped to the housing around the seal by a clamping nut. The cylinder has an outer actuation chamber while an inner annular chamber between the piston and the seal is a flushing compartment connected to a reservoir of liquid through a single duct. As the piston moves toward the seal, the liquid in the flushing compartment is expelled, taking with it any foreign matter which has gotten past the seal, and as the piston movement is reversed this compartment is filled with the liquid via this duct to flush the rod again. The valve element, valve guides, end stops, and sleeves surrounding the piston rods are all easily removable and replaceable to facilitate servicing of the valve.

Description

United States Patent Verheul [54] SLIDE VALVE FOR HIGH-VISCOSITY PUMPS [72] Inventor: Cornelis Verheul, Amsterdam, Netherlands [73] Assignee: Friedrich W. Schwing, Wanne-Eickel,

Germany [22] Filed: Feb. 3, 1970 [21] Appl. No.: 8,381

[30] Foreign Application Priority Data Feb. 5, 1969 Germany ..P 19 05 706.8

[52] US. Cl. ..137/238, 92/5 R, 92/86, 92/87, 137/607, 251/62, 251/326, 277/2 [51] Int. Cl ..F16k 41/00, F16k 3/314 [58] Field of Search ..92/5, 86, 87; 251/636, 326; 277/2; 184/18; 137/237, 238, 240, 312

[56] References Cited UNITED STATES PATENTS 1,317,563 9/1919 Eckenroth ..277/110 X 2,478,811 8/1949 Downs ..251/327 X 2,628,872 2/1953 Moore ..92/153 X Feb. 8, 1972 Primary Examiner -M. Cary Nelson Assistant Examiner-Richard Gerard Attorney-Karl F. Ross [5 7] ABSTRACT A slide valve for dense or viscous materials, e.g. concrete, has a slide element connected to a piston rod which extends out of the valve housing through a seal and carries a piston received in a cylinder which is clamped to the housing around the seal by a clamping nut. The cylinder has an outer actuation chamber while an inner annular chamber between the piston and the seal is a flushing compartment connected to a reservoir of liquid through a single duct. As the piston moves toward the seal, the liquid in the flushing compartment is expelled, taking with it any foreign matter which has gotten past the seal, and as the piston movement is reversed this compartment is filled with the liquid via this duct to flush the rod again. The valve element, valve guides, end stops, and sleeves surrounding the piston rods are all easily removable and replaceable to facilitate servicing of the valve.

13 Claims, 10 Drawing Figures SHEETlUFS INVENTOIR ATTORNEY PATENIEU FEB 8 I972 SHEET 2 [IF 5 FIG. 2A

FIG. 2B

ATTORNEY PATENIEI] FEB 8 B72 sum 5 0F 5 Ill III INVENTOR co E4/6L/5 ATTORNEY SLIDE VALVE FOR HIGH-VISCOSITY PUMPS FIELD OF THE INVENTION The present invention relates to a slide valve. More particularly, this invention relates to a slide valve assembly for controlling highly viscous matter, such as concrete.

BACKGROUND OF THE INVENTION Valves of the above-mentioned type, for use with viscous or dense materials such as concrete, include a slide valve whose slide element is connected to a rod which passes through a seal in the wall of the conduit or valve housing. The slide or valveclosure element is usually mounted on two such rods which are connected together and actuated by a single hydraulic cylinder mounted outside the conduit. When such a valve is used in conjunction with a concrete pump, for instance, granular, highly corrosive matter tends to work its way out of the conduit through the seal. To prevent this matter from contaminating the hydraulic cylinder and from drying and then wearing out the seal as the drive rod reciprocates, a small stream of washing liquid, usually water, is directed at the rods where they emerge from the conduit.

While flushing with water carries away much of the contaminating material, the use of the technique on the case of concrete when the water merely falls to the ground, creates a problem since the concrete can accumulate and harden, even under water, and permanently foul the area. Moreover, a reverse leakage of the flushing liquid often occurs to dilute or contaminate the viscous material being controlled by the valve.

Another disadvantage of such a valve structure is that the exposed, usually constantly reciprocating, drive rods create an injury hazard, the seals are often ineffective and require repeated adjustment since it can not be ascertained precisely when the seals become inoperative, and the guide means and actuating system for the slide is inordinately complex.

OBJECTS OF THE INVENTION It is, therefore, an object of the present invention to provide an improved slide valve of the above-mentioned type, especially for use with high viscosity and dense materials with abrasive characteristics.

Another object of the present invention is to provide such a valve which wears little, is easy to service, presents virtually no danger of injury to operating personnel, and is relatively inexpensive to manufacture and maintain.

It is also an important object of the invention to provide an improved reliable concrete valve for use in concrete-pump installations.

SUMMARY OF THE INVENTION The above objects are attained, in accordance with the present invention, with a valve wherein the or each control rod is provided at an end with a cylinder arrangement with a piston mounted on the rod and defining in the cylinder itself an actuating chamber remote from the slide and connected to a source of valve-operating fluid pressure, and a flushing chamber between the piston and the seal and connected via a single duct or tube to a reservoir of flushing fluid such that, on displacement of the piston toward the seal, fluid is expelled from the flushing chamber into the reservoir, and on displacement in the opposite direction, fresh flushing fluid e.g., a lubricant alone or together with water or other liquid is drawn into this chamber from the reservoir to rinse the rod. The tube thus serves as an intake upon displacement of the piston away from the seal and as an outlet upon displacement of the piston in the reverse direction.

The duct, according to another feature of the invention, opens below the liquid level into a relatively large, transparent reservoir, the entire flushing network being fully closed. In this manner, the amount of material washed off the rod can be constantly monitored so that the packing nuts can be tightened when an overly large quantity of material gets through the packings. Furthermore, the large reservoir allows the material washed off to settle out of the flushing liquid, or to rise to its surface if it is less dense. The reservoir may have a window through which the condition of the liquid (i.e., its turbidity) may be monitored, so that, in any event, the reservoir is at least partly transparent.

This cylinder is in the form ofa blind tube whose closed end forms the actuating chamber and whose open end is held by the packing nut to the valve housing or conduit. A thrust ring is placed between the open end of the tube and the outer end of the seal with its inner end bearing against the conduit, so that turning of the nut draws the cylinder toward the conduit and tightens the seal.

Preferably the mouth of the cylinder is formed with an outwardly extending flange behind which the inwardly extending flange of the packing or coupling nut engages. The mouth of the cylinder is also provided with a recess defining an inwardly extending shoulder which is clamped under axial pressure against a rigid compression sleeve or bushing. The latter fits snugly but slidably within a coaxial boss upon the valve housing, the packing or coupling nut being threaded onto this boss. Within the boss, a yieldable gland or packing ring is compressed by the sleeve and, deformed radially inwardly and outwardly against the rod and the inner wall of the boss as well as axially against the valve housing.

The valve member, its guides, and its end stops are all replaceable and removably mounted on the control rods, which are themselves protected by removable and replaceable tubular shields. This construction is very light and allows the simple and inexpensive replacement of all parts of the valve which are highly likely to wear, while those which would be difficult and expensive to replace, i.e., the control rods, are completely protected.

In accordance with another feature of the invention, only a single control rod is provided on each valve element, and two such elements can be mounted on a single such rod with a cylinder arrangement at each end.

The invention also provides that the rod, as this term is used hereinabove, may comprise a coaxial arrangement of an outer wear tube or sleeve, which closely surrounds the inner rod member, extending from the piston to the slider and completely but removably shielding the inner rod. The wear tube or sleeve represents the portion of the rod cooperating with the seal and flushed in the compartment ahead of the piston. The wear tube or sleeve is clamped axially against the slide by the piston-securing nuts.

DESCRIPTION OF THE DRAWING The above and other objects, features, and advantages will become apparent from the following description, reference being made to the drawing, in which:

FIG. 1 is a partly sectional view through a valve and conduit arrangement according to the present invention;

FIG. 2A is a partly sectional view showing the valve element according to the present invention;

FIG. 2B is a section along line IIB-IIB of FIG. 2A;

FIG. 3A is a view of one of the valve guides, according to the present invention, to the same scale as FIGS. 2A and 28;

FIG. 3B is a section along line IIIB-IIIB of FIG. 3A;

FIG. 4A is an end view, to the same scale as FIGS. 2A3B, of part of the valve seat according to the present invention;

FIG. 4B is a section along line lVB-IVB of FIG. 4A;

FIG. SA is a view similar to FIG. 1A showing an alternative embodiment of the present invention;

FIG. 5B is a section along line VB-VB of FIG. 5A; and

FIG. 6 is a partly sectional view showing an installation using thevalve of FIGS. 5A and 5B.

SPECIFIC DESCRIPTION A concrete-pump control valve 1 has a slider 2 which can block one of two conduits 3. In FIG. 1 the right-hand conduit is blocked. The slider 2, as shown in FIGS. 2A and 2B comprises a flat center portion 2a which is symmetrical about an axis A and has two semicircular ends 2b. Each end 2b has a radius of curvature r equal to that of the conduits 3. To each side of the center portion 2a is welded a tube 19 having an internal diameter d and an external diameter d The slider 2 is carried on a pair of steel piston rods 4 which have an outer diameter equal to d so that they just fit in the tubes 19. At each end of each of the rods 4 is a small threaded portion 4a on which a nut 4b holds a plurality of washers 40 which form a piston 12. Each rod 4 passes out through the wall 18 of the conduit or through the valve housing and through a packing 5, and thence into a hydraulic actuating cylinder 6.

The cylinder 6 comprises a blind cylindrical tube 13 having a regular cross-sectional area and an inside diameter D larger than d which is in turn larger than 11,. A pressurizable and depressurizable chamber 13a is thus formed to the right of the piston 12 as seen in FIG. 1. By the same token, closed annular chamber 7 is formed to the left of this piston 12, for reasons which will be described below.

Adjacent the conduit or valve housing 18 the cylinder 13 abuts with its end 14 a metal ring 11 that serves to compress the packing ring 5. To this end the cylinder 13 is formed adjacent the housing 18 with an outwardly extending flange 15 which can be engaged by a packing nut 16 that screws onto a nipple 17 formed on the housing 18.

The entire rod 4 is sheathed between both of its pistons 12 by the tube 19 of the element 2 and two tubes or sleeves 10 having the same inside and outside diameters as the tubes 19. In this manner the rod 4 itself at no point is directly exposed to wear.

The element 2 slide between a pair of guide plates 20 shown in FIGS. 3A and 33. Each plate 20 has a relatively thin center portion 20a having two oppositely directed circular cutouts 22 of radius of curvature r which is the same radius of curvature as the conduit 3 and the ends 2b of the elements 2. To each side of the center section 20a is a ridge 21a defining a semicylindrical recess 21 of diameter d Since the element 2 is adapted to move back and forth to block and unblock one of two conduits 3, it is clear how it will slide between these two guides 20 with the semicylindrical grooves receiving the

tubes

19 and 10.

Defining the limit of travel of the element 2 at each end is a pair of stop elements 23, one of which is shown in FIGS. 4A and 48. Each element 23 is in the form of a block with a throughgoing bore 21a of diameter 11 and having a corner rounded at 220 with a radius of curvature equal to r.

FIGS. 5A and 5B show a valve 1 essentially the same as that of FIGS. 148 except that here the valve element 2 is connected to only one rod 4 and a one-piece end stop 23 is provided. FIG. 5B shows how the plates 20 hug the element 2.

In FIG. 6 there is shown a typical installation wherein two conduits 26 both lead to a supply of concrete. Two inlet conduits 27 lead upwardly from the conduits 26 to opposite chambers of a pump 27, preferably a rocker-arm pump. Furthermore, both conduits 27 lead down to an outlet base 28 leading to wherever the concrete is to be pumped. Two elements 2' are mounted on a common piston rod 4 extending between two piston-and-cylinder arrangements 6 so that at one time only one conduit 26 and the opposite conduit 27 can be open. Thus, as the pump 27 draws a charge of concrete up through the right-hand conduit 26 it simultaneously expels a previously obtained charge down through the left-hand conduit 27. Then the valve is reversed by synchronized control 25 so that a charge can be drawn up through the left-hand conduit 26 and the previously picked up charge can be pushed out through the right-hand conduit 27. In this manner a relatively steady flow is created in the conduit 28, as long as the switching time for the elements 2' is reasonably short.

The valve of FIG. 1 is operated by a pump 25 which can be connected through a selector valve 25 and conduits 24 to the cylinders 13 to displace the pistons 12 therein. In normal use this valve 25 is moved back and forth to move the element 2 back and forth, as is described immediately above.

The chambers 7 are fully sealed except where a duct 8 which has one end in a reservoir 9 filled with shale oil or an oil-water emulsion, or even common oil, or other liquid which does not attack and is not attacked by concrete so that as the piston 12 moves back and forth this flushing fluid is sucked into and expelled from the chamber 7. The reservoir 9 and the tubes 8 are preferably made of transparent material so that any foreign matter entering the chamber 7 through the seal 5 can quickly be seen. The fluid must have a density different from that of the particles likely to get past the seal 5 so that these particles will either settle out or rise to the surface in the reservoir 9.

Should such particles become visible in either the reservoir 9 or tubes 8, one or all of the packing nuts 16 is rotated to tighten the seal 5. In prior art systems it has always been necessary to simply periodically tighten all of the seals to prevent leaks, thereby greatly increasing the power loss caused by friction and the amount of wear of these seals.

Furthermore, should the valve 1 need overhauling, all ofthe parts exposed to wear, which are all of steel, can be quickly and simply replaced. The valve housing 18 must be opened at one side and all four cylinders 13 removed. Then then the nuts 4b at one side of the valve are removed, and the rods 4 pulled entirely out through the other side of the valve 1. New blocks 23, guides 20, protecting sleeves 10, valve element 2, and seals 5 can be quickly mounted, and the device reassembled. Such an overhaul can be carried out by a semiskilled worker in a very short time, and the necessary new parts are of nominal cost.

Iclaim:

l. A slide valve for a conduit, comprising:

a slidable valve element in said conduit displaceable into and out of a position blocking same;

a rod connected to said element and passing out through a wall of said conduit;

a piston on said rod external of said conduit;

a seal in the wall of said conduit tightly surrounding said rod;

a fluid cylinder external of said conduit surrounding said rod and receiving said piston, said piston subdividing said cylinder into a flushing compartment between said piston and said seal and an actuating compartment on the other side of said piston;

a reservoir containing a flushing fluid; and

duct means connecting said reservoir to said flushing compartment for drawing said fluid into said flushing compartment upon displacement of said element in one direction and for expelling said fluid from said flushing compartment on displacement of said element in the other direction, said cylinder being of regular cross-sectional area, the cross-sectional area of said piston being greater than that of said rod, said flushing compartment being annular and surrounding said rod, said rod comprising an inner rod member and an outer replaceable and removable sleeve member, said valve element being formed with at least one tube portion having a throughgoing bore fitting said inner rod member, said valve having one such cylinder at each end of said rod, said sleeve members extending fully between said tube portion and said pistons and being clamped in place by same.

2. The valve defined in claim 1 wherein said cylinder includes a blind tube having a closed end forming said actuating compartment and an open end directed toward said seal.

3. The valve defined in claim 2, further comprising a clamp nut threadedly engaging said conduit around said seal and having an internal flange, said conduit having an external flange entrained by said nut in the direction of said conduit.

4. The valve defined in claim 3, further comprising a thrust ring between said open end ofsaid tube and said seal, whereby rotation of said nut compresses and tightens said seal.

5. The valve defined in claim 1, further comprising a pair of replaceable and removable guide members flanking and slidably receiving said valve element.

6. The valve defined in claim 1 wherein said reservoir is at least partially transparent.

7. A slide valve for a conduit comprising:

a rod connected to said element and passing out through a wall of said conduit;

a piston on said rod external of said conduit;

a seal in the wall of said conduit tightly surrounding said rod; 7

a reservoir containing a flushing fluid;

duct means connecting said reservoir to said flushing compartment for drawing said fluid into said flushing compartment upon displacement of said element in one direction and for expelling said fluid from said flushing compartment on displacement of said element in the other direction; said cylinder being of regular cross-sectional area, the cross-sectional area of said piston being greater than that of said rod, said flushing compartment being annular and surrounding said rod;

a pair of replaceable and removable guide members flanking and slidably receiving said valve element; and

at least two end-stop members engageable with said element at the limit of travel thereof, said guide members each being formed with matching substantially semicylindrical grooves and said stop members being formed with throughgoing holes, said grooves and said holes forming a throughgoing bore of regular diameter snugly slidably receiving said rod.

8. The valve defined in claim 7 wherein said rod comprises an inner rod member and an outer replaceable and removable sleeve member.

9. The valve defined in claim 8 wherein said valve element is formed with at least one tube portion having a throughgoing bore fitting said inner rod member.

10. The valve defined in claim 7 wherein said valve element is connected to a pair of such rods.

11. A slide valve for a conduit comprising:

a rod connected to said element and passing out through a wall of said conduit;

a piston on said rod external of said conduit;

a seal in the wall of said conduit tightly surrounding said rod;

a fluid cylinder external of said conduit surrounding said rod and receiving said piston, said piston subdividing said cylinder into a flushing compartment between said piston and said seal and an actuating compartment on the other side ofsaid piston;

a reservoir containing a flushing fluid;

duct means connecting said reservoir to said flushing compartment for drawing said fluid into said flushing compartment upon displacement of said element in one direction and for expelling said fluid from said flushing compartment on displacement of said element in the other direction;

a pair of substantially flat replaceable and removable guide members flanking and slidably receiving said element, said guide members being formed with opposing substantially semicylindrical grooves;

a pair of end-stop members engageable with said element at the extreme limit of travel thereof, said stop members being formed with throughgoing holes, said holes and said grooves defining an axially extending straight bore snugly fitting said rod, said rod having one such cylinder at each end and including an inner rod member carrying at each of its ends one such piston and a sleeve member extending between each of said pistons and said element, said element being formed with tube portion clamped between said sleeve members and having a bore receiving said rod member;

a nut having an internal flange and threadedly engaging said conduit around said seal, said cylinder being a blind tube having a closed end forming said actuating compartment and an open end directed toward said seal and formed with an external flange and an internal shoulder, said internal flange bearing on said external flange; and

a thrust sleeve between said internal shoulder and said seal whereby rotation of said nut tightens said seal, said reservoir being at least partially transparent, said guide and end-stop members forming a substantially circular opening corresponding to the internal diameter of said conduit and in line therewith, said flushing compartment being annular and surrounding said rod between said seal and said piston.

12. A slide valve for a conduit comprising:

a rod connected to said element and passing out through a wall of said conduit;

a piston on said rod external of said conduit;

21 seal in the wall of said conduit tightly surrounding said rod and provided with means for tightening the seal upon wear thereof;

a reservoir containing a flushing fluid; and

a flushing duct connecting said reservoir to said flushing compartment for drawing said fluid into said flushing compartment upon displacement of said element in one direction and for expelling said fluid from said flushing compartment on displacement of said element in the other direction.

13. The slide valve defined in claim 12 wherein said valve element is provided with a respective rod on opposite sides thereof and extending in the direction of displacement of said valve element, each of said rods being provided with a respective piston, seal, fluid cylinder and flushing duct is defined.

Claims

1. A slide valve for a conduit, comprising: a slidable valve element in said conduit displaceable into and out of a position blocking same; a rod connected to said element and passing out through a wall of said conduit; a piston on said rod external of said conduit; a seal in the wall of said conduit tightly surrounding said rod; a fluid cylinder exterNal of said conduit surrounding said rod and receiving said piston, said piston subdividing said cylinder into a flushing compartment between said piston and said seal and an actuating compartment on the other side of said piston; a reservoir containing a flushing fluid; and duct means connecting said reservoir to said flushing compartment for drawing said fluid into said flushing compartment upon displacement of said element in one direction and for expelling said fluid from said flushing compartment on displacement of said element in the other direction, said cylinder being of regular cross-sectional area, the crosssectional area of said piston being greater than that of said rod, said flushing compartment being annular and surrounding said rod, said rod comprising an inner rod member and an outer replaceable and removable sleeve member, said valve element being formed with at least one tube portion having a throughgoing bore fitting said inner rod member, said valve having one such cylinder at each end of said rod, said sleeve members extending fully between said tube portion and said pistons and being clamped in place by same.

4. The valve defined in claim 3, further comprising a thrust ring between said open end of said tube and said seal, whereby rotation of said nut compresses and tightens said seal.

7. A slide valve for a conduit comprising: a slidable valve element in said conduit displaceable into and out of a position blocking same; a rod connected to said element and passing out through a wall of said conduit; a piston on said rod external of said conduit; a seal in the wall of said conduit tightly surrounding said rod; a fluid cylinder external of said conduit surrounding said rod and receiving said piston, said piston subdividing said cylinder into a flushing compartment between said piston and said seal and an actuating compartment on the other side of said piston; a reservoir containing a flushing fluid; duct means connecting said reservoir to said flushing compartment for drawing said fluid into said flushing compartment upon displacement of said element in one direction and for expelling said fluid from said flushing compartment on displacement of said element in the other direction; said cylinder being of regular cross-sectional area, the cross-sectional area of said piston being greater than that of said rod, said flushing compartment being annular and surrounding said rod; a pair of replaceable and removable guide members flanking and slidably receiving said valve element; and at least two end-stop members engageable with said element at the limit of travel thereof, said guide members each being formed with matching substantially semicylindrical grooves and said stop members being formed with throughgoing holes, said grooves and said holes forming a throughgoing bore of regular diameter snugly slidably receiving said rod.

11. A slide valve for a conduit comprising: a slidable valve element in said conduit displaceable into and out of a position blocking same; a rod connected to said element and passing out through a wall of said conduit; a piston on said rod external of said conduit; a seal in the wall of said conduit tightly surrounding said rod; a fluid cylinder external of said conduit surrounding said rod and receiving said piston, said piston subdividing said cylinder into a flushing compartment between said piston and said seal and an actuating compartment on the other side of said piston; a reservoir containing a flushing fluid; duct means connecting said reservoir to said flushing compartment for drawing said fluid into said flushing compartment upon displacement of said element in one direction and for expelling said fluid from said flushing compartment on displacement of said element in the other direction; a pair of substantially flat replaceable and removable guide members flanking and slidably receiving said element, said guide members being formed with opposing substantially semicylindrical grooves; a pair of end-stop members engageable with said element at the extreme limit of travel thereof, said stop members being formed with throughgoing holes, said holes and said grooves defining an axially extending straight bore snugly fitting said rod, said rod having one such cylinder at each end and including an inner rod member carrying at each of its ends one such piston and a sleeve member extending between each of said pistons and said element, said element being formed with tube portion clamped between said sleeve members and having a bore receiving said rod member; a nut having an internal flange and threadedly engaging said conduit around said seal, said cylinder being a blind tube having a closed end forming said actuating compartment and an open end directed toward said seal and formed with an external flange and an internal shoulder, said internal flange bearing on said external flange; and a thrust sleeve between said internal shoulder and said seal whereby rotation of said nut tightens said seal, said reservoir being at least partially transparent, said guide and end-stop members forming a substantially circular opening corresponding to the internal diameter of said conduit and in line therewith, said flushing compartment being annular and surrounding said rod between said seal and said piston.

12. A slide valve for a conduit comprising: a slidable valve element in said conduit displaceable into and out of a position blocking same; a rod connected to said element and passing out through a wall of said conduit; a piston on said rod external of said conduit; a seal in the wall of said conduit tightly surrounding said rod and provided with means for tightening the seal upon wear thereof; a fluid cylinder external of said conduit surrounding said rod and receiving said piston, said piston subdividing said cylinder into a flushing compartment between said piston and said seal and an actuating compartment on the other side of said piston; a reservoir containing a flushing fluid; and a flushing duct connecting said reservoir to said flushing compartment for drawing said fluid into said flushing compartment upon displacement of said element in one direction and for expelling said fluid from said flushing compartment on displacement of said element in the other direction.

13. The slide valve defined in claim 12 wherein said valve element is provided with a respective rod on opposite sides thereof and extending in the direction of displacement of said valve element, each of said rods being provided with a respective piston, seal, fluid cylinder and flushing duct as defined.