US2341394A - Throttling device - Google Patents

Description

Feb. 8, 1944. w. E. SLOAN THROTTLING DEVICE Filed March 8, 1938 IIIIIIIIIII INVENTOR gg/5 54mm ATTORNEY Patented Feb. 8, 1944 THROTTLING DEVIGE William E. Sloan, River Forest, 111., assignor to Sloan Valve Company,-Chicago, 111., a corporation of Illinois Application Marsh 8, 1938, Serial No. 194,633

2 Claims.

The present invention relates to throttling devices, and has for its main object the production of new and improved devices which will permit of the quiet throttling of a relatively high rate of flow from a high-pressure source of liquid.

In carrying out the objects of the invention, a throttling device has been produced in which the liquid is caused to flow between substantially parallel roughened surfaces which are caused to overlap one another more or less ac cording to the supply pressure and the desired rate of flow. One of the roughened surfaces is preferably the inside surface of a cylindrical water passage, the other and cooperating roughened surface being the outside surface of a plug or cylinder which is adjustable more or less within the first-mentioned roughened surface. The diameter of the plug is preferably less than the inside diameter of the passageway by several thousandths of an inch, whereby the liquid flows in a. thin annular sheet between the two roughened surfaces, the velocity of the annular sheet being thereby retarded by each of the two roughened surfaces between which the annular sheet of liquid passes.

Experience has indicated that, whatever the explanation for the noise produced by the flow of water from high pressure to low pressure, the generation of noise is always accompanied by a relatively high velocity. The quiet throttling action of the devices herein illustrated, constructed according to the present invention, is believed to be derived largely from the reduction in velocity of the flowing liquid to a point below the critical noise-making velocity.

With respect to the form which the roughening of the two cooperating surfaces takes, standard screw threads have been found to be satisfactory, as well as standard forms of knurling, such as that of the well-known diamond knurl. The roughening on both surfaces may be the same, or one surface may be roughened by threading, while the cooperating surface is roughened by diamond knurling. The choice of one or the other form of roughening depends largely upon manufacturing and size considerations, keeping in mind such things as ratio of length of overlap to the mean diameter of the cooperating roughened surfaces.

A feature of the invention herein illustrated is that the desired rate of flow may be secured from lower pressures by merely reducing the overlap the required amount. The overlap of the two roughened surfaces is entirely eliminated, and the minimum area through the throttling device is greatly enlarged, by withdrawing the plug entirely from the cooperating passageway. Effective Silencing in the zone of transition from overlap to no overlap is produced by slightly flaring the entrance to the passageway, as well as by silghtly tapering or rounding the cooperating end of the plug.

Other objects and features of the invention will become more apparent upon a further perusal of the specification.

Referring now to the accompanying drawing, comprising Figs. 1 to 7, they show sufficient views of devices constructed according to the features of the invention to enable the invention to be understood.

Figures 1 and 2 show a small-scale top view and front view, respectively, of a flush valve installation wherein the improved quiet throttling device 3 is inserted between the usual stop or valve 2 and the flush valve 4;

Figure 3 is a full-scale sectional View of the improved quiet throttling device 3 illustrated in Figs. 1 and 2; 7

Figures 4 and 5 show a small-scale top view and front view of a flush valve installation wherein the controlling stop of conventional design has been'replaced by an improved quiet throttling stop valve .32;

Figure 6 is a full-scale sectional view of the quiet throttling stop I82, shown in full in Figs. 4 and 5; and

Figure '7 is an enlarged view of the lower righthand corner of the nipple or tail-piece [5 of the throttling device 3, Fig. 5, illustrating the thread form used on the inside surface.

Referring now particularly to Figs. 1 and 2, in the illustrated installation the supply pipe I extends through a wall to the inlet of the stop or shut-off valve 2, the exit of the supply pipe from the wall being covered by the usual Wall flange l. The outlet of the stop Zis connected by the usual tail-piece and ground-joint union to the inlet 52 of the quiet throttling device 3. In turn, the outlet E5 of the quiet throttling device 3 is screw-threaded into the inlet of the flush valve l. The discharge tube 6 is connected to the outlet of the flush valve l to carry water to the receptacle to be flushed, the flushing action being initiated by an operation of the handle 5' of the flush valve.

In this installation, the stop 2 is used to shut off the supply entirely when either the throttling device 3 or the flush valve l is to be inspected or repaired, being turned wide open for regular operation. The rate of flow of water through the flush valve 4 and discharge tube 6 to the receptacle to be flushed is regulated by a suitable adjustment of the throttling device 3.

Referring now particularly to Fig. 3, the construction of the throttling device 3 will now be described in detail. The casing H has the form and general dimensions of a 1-inch T fitting, the inlet opening being at ii, the outlet opening at 13, and the bonnet opening at M. The inlet opening I2 is inside-threaded in the usual mans ner to receive either a standard 1-inch pipe or nipple. The outlet opening l3 and the bonnet opening 14 are outside threaded to enable the outlet tail-piece l5 and the bonnet [8 to be secured in place by coupling nuts 20 and IS.

The inside surface of the outlet tail-piece I5 is roughened by scoring-which may conveniently take the form of the thread cut by a standard threading tool. The thread chosen is preferably one with a fiat top, as is illustrated best in Fig. '7, an enlarged showing of the lower right-hand corner of the outlet piece iii. The entrance to the outlet piece I5 is preferably flared as illustrated, and this flared portion preferably has its surface roughened by scoring.

Although the form of the thread used and the number of threads to the inch has not been found to be critical, a thread form similar to that of Briggs standard pipe thread, particularly as customarily modified to give a comparatively sharp bottom and a comparatively flat top is satisfactory. The efficiency, however, is increased somewhat by arranging the cutting tool so that the width of the fiat on the top of the thread is somewhat greater than is commonly used, approaching the proportion of fiat used in an acme thread. It seems to be immaterial whether the bottom of the thread is flat or sharp.

Variable throttling is produced by the throttle piece or cylindrical plug l6, fixed to the adjustable stem ll. The stem I1 is screw-threaded into the bonnet l8. A water-tight connection with the smooth outer end of the stem H is maintained by the packing 2|, held in place by the packing nut 22.

The surface of the adjustable plug it is rough encd by diamond knurling as illustrated, there being about thirty elevations to the inch in the direction of flow, separated by a corresponding number of valleys.

As illustrated, there is a substantial clearance between the surface of the plug l6 and the inside surface of the discharge piece l5, whereby the liquid passing through the device in the illustrated position of adjustment takes the form of an annular sheet or tube at the point of greatest restriction. For the purpose illustrated, there may be a clearance between the plug l6 and the inside of the barrel l5 of about .020 inch on each side, there being a total difference in diameter of about .040 inch. With this clearance, and with the roughened surfaces illustrated and described hereinbefore, a quiet rate of flow of from twelve to fourteen gallons a minute can be secured from a high pressure source with the plug l5 adjusted into the discharge piece 5 to give an overlap of between inch and A; inch of the straight portion at a pressure of thirty pounds to the square inch, the overlap being increased about inch for each ten pounds increase in supplied pressure. When this is carried out, it will be found that an overlap of about inch to one inch gives a rate of flow of between twelve and fourteen gallons a minute at a line pressure of one hundred pounds. The illustrated plug l6 and cooperating barrel are of such length that a quiet discharge of twelve to fourteen gallons a minute can be obtained from line pressures approaching two hundred pounds to the square inch.

In order to obtain a rate of flow of from twelve to fourteen gallons a minute quietly from a supplied pressure of less than thirty pounds to the square inch, the overlap of between inch and inch used at about thirty pounds pressure is correspondingly decreased, the straight portion of the overlap being lost entirely at a pressure of from twenty to twenty-five pounds to the square inch. At such a pressure, the tapered or rounded forward end of the plug I6 is Within the tapered entrance to the inside-threaded piece [5, and the throttling is then performed between the conical surface of the flared entrance to the part l5 and the correspondingly shaped end of the throttle piece l6. For pressures on down to about fifteen pounds to the square inch, very little length is required in the throttling restriction to provide silence, as the maximum velocity which can be obtained at a pressure of fifteen pounds is just at or below the critical noisemaking velocity. Experiment has demonstrated rather conclusively that no objectionable noises are produced with any form of throttling device when the pressure is at or below fifteen pounds to the square inch.

For very low pressures, the piece I6 may be withdrawn entirely from the vicinity of the entrance to the outlet piece 15, giving a full unrestricted one-inch waterway.

As previously discussed, the device illustrated in detail in Fig. 3, and illustrated in an installation in Figs. 1 and 2, is capable of giving a quiet rate of flow up to twelve to fourteen gallons 9. minute from a supply pressure high enough to generate objectionable noise if not properly throttled. This rate of flow is ample to flush many receptacles, such as most forms of urinals, and some types of water closets. A greater rate of flow with substantially the same quietness can be provided with the device of Fig. 3 by merely increasing the difference between the diameter of the plug l6 and the inside diameter of the piece I5, but this reduces the maximum pressure that the device will handle quietly, for a much greater overlap is required to effectively silence the flow when the crevice or clearance is increased somewhat.

A second plan for increasing the capacity of the device is to increase the diameter of the plug 16 and the inside diameter of the piece l5, directly with the desired increase in the rate of flow, keeping the clearance between the parts the same. For example, since the device illustrated in Fig. 3 gives a quiet rate of flow of twelve to fourteen gallons a minute from high pressure, with the inside diameter of the piece 15 at one inch, a similarly constructed device wherein the part l5 has an inside diameter of two inches would give a quiet rate of flow of from twenty-four to twenty-eight gallons a minute, provided the diameter of the part I6 is suitably increased to give the same clearance as before.

Experiments have indicated that the surface of the plug l6 and the inside surface of the discharge piece !5 may be relatively smooth without giving a noisy flow, provided the clearance between the parts be reduced until it is only a few thousandths of an inch, or provided the overlap is increased by a substantial amount. In general, the smoother the wall, the less the allowable clearance; consequently, the less the rate of flow which can be secured with substantial si-, lence. For many situations, a throttling device on the order of that illustrated in Fig. 3 may prove quite satisfactory with one wall roughened (such as by threading, knurling, etc.), and the other wall comparatively smooth. This combination gives a quiet rate of flow somewhat in excess of half the rate of flow that can be obtained when both walls are roughened, for the allowable clearance is then only slightly in excess of half the allowable clearance when both walls are roughened.

Referring now particularly to Figs. 4 to 6, modified form of the invention will be described. In Figs. 4 and 5, the quiet throttling stop 502 is shown disposed between a supply pipe NH and a flush valve I04, the connection between the quiet stop i132 and the flush valve I04 being made through the customary nipple or tail-piece Hit. The flange i! is used to conceal the exit from the wall of the supply pipe NH. The flush valve Hi4 may be actuated by the handle I05 to discharge a metered quantity of water through the discharge tube I06 to the receptacle to be flushed.

In Fig. 6, the stop Hi2 has a casing IH, with the inlet H2 and the outside-threaded discharge port at H3, the inside of which is ground to receive the male portion of the usual groundjoint union. A plug l 55 has a threaded or scored surface to enable it to cooperate with the inside surface H9 of the throttling barrel. The plug H5 is secured to, and is controlled by, the stem H8 to give a desired overlap of the plug Within the barrel, according to the desired rate of flow and according to the supply pressure. The stem i 3 is controlled by the handle I23, being threadably secured in the bonnet which is tightly secured in the bonnet opening l M. The packing i2! is held in place by the nut I 22 to prevent leakage out around the stem I 98.

The reinforced rubber seat H0 is supported by the back plate or disc Hl against bending or cupping when the stop is closed tightly against the seat provided around the mouth of the throat in which the plug H5 operates.

The plug H5 has its diameter reduced somewhat for about the first inch of lemth. The lack of full scored diameter in the vicinity of the rubber seat is immaterial to the silent action, as the device is designed to give the correct rate of flow when the stop is opened about one turn, in which case about the first inch of the plug is withdrawn. By this construction the area over which the rubber seat member H6 is clamped is lessened sufiiciently that only smooth rubber, undistorted by clamping, is presented to the fixed seating surface. This arrangement favors nonchattering seating and unseating of the valve, as does the substantial radius at the exposed corner of the seat member H5.

In proportioning the device of Fig. 6 to give a rate of flow of up to fifteen gallons a minute quietly from a line pressure slightly exceeding one hundred pounds to the square inch, good results were obtained with the barrel H9 made with an inside diameter of 1 inches, with a clearance between the surface of the plug and the inside surface of the barrel of about .015 inch, or a total difference of diameter of .030 inch. Under this condition, a total length of the plug from the surface of the seat H6 of one inch was found to be ample when the scoring or roughening of the surfaces H5 and H9 was made by threading thirty-six threads to the inch of standard Whitworth form, except for a flat top about .008 inch wide. With a pressure of one hundred pounds, the desired rate of flow is given when the device is open about one turn. For successively lower inlet pressures, the device is opened greater distances, somewhat as described in connection with the device in Fig. 3. The desired rate of flow may be obtained with substantial silence at any pressure below one hundred pounds by a suitable adjustment.

It is to be noted that the barrel H9 is longer than the plug H5, and that the scoring of the barrel is continued to the point where it begins to contract near the outlet H3 to provide for the ground-joint union. It has been found that the additional, apparently unused scoring or roughening on the barrel is of material aid in slowing up the annular stream after it leaves the actual throttling restriction. It was found that a greater rate of flow can be handled quietly with the additional roughened surface than can be handled when only that part of the barrel is roughened which can be overlapped by the plug at the setting of greatest overlap.

What is claimed is:

1. In a combined throttle and shut-off valve comprising a casing having an inlet and an enlarged interior, a restricted outlet passageway having a seating shoulder extending around it, a throttle piece telescopable within said passageway and adjustable axially thereof, said throttle piece and said passageway having cylindrical spaced apart parallel wall surfaces when the throttle piece is adjusted into said passageway, a disk of relatively rigid material opposed to the end of the throttle piece, a ring of flexible distortable material clamped between the disk and the throttle piece and adapted to serve as a seating shoulder cooperating with the outlet seating shoulder to close communication between the interior and the outlet passageway when the throttle piece is adjusted the maximum amount into said passageway, said throttle piece having a portion of reduced diameter immediately adjacent said disk and ring, adapted to provide space for the flexible material when extruded from between the disk and the throttle piece.

2. In a combined throttle and shut-01f valve comprising a casing having an inlet and an enlarged interior, a restricted outlet passageway having a seating shoulder extending around it, a throttle piece telescopable within said passageway and adjustable axially thereof, said throttle piece and said passageway having cylindrical spaced apart parallel wall surfaces when the throttle piece is adjusted into said passageway, a seating shoulder on said throttle piece cooperating with said outlet seating shoulder to close communication between the interior and the outlet passageway when the throttle piece is adjusted the maximum amount into said passageway, said shoulder including a disc of rigid material, and a ring of flexible distortable material clamped between the disc of rigid material and the throttle piece, said disc and ring being of substantially greater diameter than the throttle piece, the throttle piece including a portion of reduced diameter directly adjacent said ring of flexible distortable material, adapted to provide space for said flexible distortable material as it is distorted when the valve is closed, and as it is extruded from between the disk and the throttle piece.

WILLIAM E. SLOAN.

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