US2037737A - Quiet flow retarding device - Google Patents

Description

April 3 w. F. PETERSON El AL r 2,037,737

QUIET FLOW RETARDING DEVICE Filed July 31, 1954 Patented A r. 21, 1936 UNITED STATES PATENT OFFICE QUIET FLOW RETARDING DEVICE ApplicationlulyBl, 1934, Serial No. 737,842 6 Claims. (cries-4o) This invention is a new and useful device and operates for throttling or retarding the flow of liquids with a minimum of noise at the device and in the apparatus as a whole.

An object of this invention is to provide quiet, simple and inexpensive means for retarding the flow of liquid at some point in the distributing system so as to reduce the velocity of flow in the rest of the system to such an extent that objectionable noise will be reduced or eliminated.

Another object of the invention is to provide simple and inexpensive means for reducing the noise occurring in toilet flushing tanks, both during the full flow for refilling the tank, and

during the termination or final shut-oil of such flow at the ball cock or float valve thereof.

Further features and objects of the invention will appear in the course of the following specification and claims.

Since a toilet flushing tank with its ball cock or float valve provides a common instance of an apparatus in which noise is undesirable, such an apparatus is used illustratively in this de scrlption as an example of employment -of the 2 retarding device and apparatus of the present invention. In the accompanying drawing:

Figure l is an upright sectional view through a toilet flushing tank having therein a retarding device embodying the present invention;

Figure 2 is an upright sectional view on a larger scale through the float valve structure;

Figure 3 is a side elevation of a quieting discharge device as shownin Figures 1 and 2; 35 Figure 4 is an end view of the same;

Figure 5 is a view corresponding to Figure l, of a modified form of employment of the invention.

It is known that the flow of a confined liquid such as water, under pressure, in pipes, valves and fittings, causes noise when the velocity of the water exceeds certain limits. Such a limit of velocity, above which noise occurs and herein called the critical velocity, depends upon many 45 conditions. Water at a relatively low velocity will cause noise if there is an abrupt or sudden change in the direction or rate of flow, while water at a much higher velocity will not cause noise if the change in direction or rate of flow 50 is more gradual. Among other factors deter mining the critical velocity above which noise will occur, and the amount and character or noise which occm's at a given velocity, are the amount of absorbed gases contained in the water, .55 the vapor tension of the water due to its temperature, and the absolute pressure of the water downstreamward, or at the low pressure side, of the restriction, obstruction or void.

The above is more or less generally known in the art and many devices have been proposed 5 and used for retarding the flow below the critical ,velocity at which noise occurs or in other words to obtain quietness. Some of such devices have been successful in reducing the flow and thereby reducing or eliminating the noise where m it previously occurred but they are noisy in themselves and thereby accomplish no net re sults. Other devices have been successful in quietly retarding the flow and eliminating the noise elsewhere but their rate of flow has been 15 insufficient for practical purposes. Such devices generally comprising long tortuous passageways, are cumbersome, complicated and expensive.

A round discharge tube leading from the body of the float valve into the tank, commonly called 20 the hush tube, of sufliciently small internal diameter to provide the proper amount of retardation for satisfactory quiet performance at the valve proper, operates fairly quietly in itself. However, such a retarding device has so high a discharge velocity and such a small perimeter for its cross-sectional area as to create considerable noise under high pressure at discharge into the tank and to create a violent and undesirable turbulence in the tank itself.

Therefore the problem is to obtain a retarding device with sullicient how for practical purposes, which is quiet in itself, which does not cause objectionable turbulence in the tank and which, at the same time, is compact, simple and inexpensive.

In the employment of such devices where the liquid is to be discharged into an open receptaole, the absolute pressure at discharge is close to atmospheric, and pressure differential effects have demanded consideration in design of quiet retarding devices.

With the illustrated toilet flushing tank as an example, the water comes to rest at atmospheric pressure at or following the refilling period, A certain minimum volume flow per unit of time is demanded in order to obtain satisfactory operating conditions, and hence'there is a certain minimum cross-section of flow required under operating pressures. These operating pressures themselves vary from place to place within a given city; and usually vary from hour to hour even at the-same outlet, due to varying con sumptions in the city; hence, the device for re; tarding the flow must be operative under consid cal velocity above which noise occurs.

erable variations oi! pressure condition, of temperature, and of absorbed gases.

It has been found that the shape of the crosssection of flow and of discharge has a most important influence upon the amount of noise or upon the critical velocity at which noise occurs;

and that the thinner or narrower the cross-section, the quieter the flow, or the higher the criti- In particular, a desirable cross-section of flow can be obtained in a very simple, cheap and effective manner by simply flattening a section of a tube.

An essential point of the invention, therefore, is to provide a passage for the liquid of such cross-section that a thin sheet of liquid is maintained between opposite walls, so that each filament in the flowing stream is closely adjacent to a wall which produces a retarding effect directly or indirectly thereon. Further, in the illustrated forms, such a cross-section of flow continues beyond the point of discharge so that a thin, wide sheet of liquid is discharged into a general body of liquid, the discharge orifice being spaced from all walls of the chamber containing this free body of liquid, so that the liquid in the free body may be carried along with the newly issuing liquid and thus eilfect a marked, yet constant, retarding influence thereupon.

With such a cross-section of flow within the tube and discharge, a maximum perimeter for a given cross-sectional area of flow is obtained. This gives a maximum retarding effect by the walls of the tube and by the general body of free liquid in the tank. Such a cross-section of flow presents the greatest contact surface per unit of volume of flow, and hence gives the most eifective deceleration of the entering liquid. Thus aminimum of turbulence is set up. It has been found that this is one of the more important considerations in obtaining quiet retardation 0! flow.

In the drawing, the flush tank or receptacle I0 is conventionally illustrated as having a discharge controlled by a valve Ila and a water supply pipe l2. These pipes pass through the bottom of the tank and are sealed in the usual manner. Inside of the tank the riser supply connection l3 leads to the fioat valve head M which has the usual valve closure l5 movable therein to shut off the fiow of water. This closure member is controlled by the usual valve float 15a. The inner chamber of the head H, downstream- Ward of the valve seat, is in free communication with a drop conduit I6 which here operates as a back-pressure producing and silent discharge device.-

This device is illustrated in a simple form which can be produced by threading one end l6a of a tube so that the device is supported in the head ll. This is the inlet end of the tube.

The tube is flattened from its other or outlet end for a distance of say three or more inches. This is permitted by the normal size and,shape of those parts which are substantially standardized at the present time. This iiatteningis so effected in the illustrated form that plane parallel opposed walls are provided. Said walls 'are closely spaced and joined by simple arches at their ends. Such a device for the standard ball cock may be formed of standard tubing of one hali inch outside diameter and of the desired length, this tubing being threaded and flattened as stated above. The perimeter of the tubing remains substantially unchanged, but a gradual transition or change of shape is provided from the cylindrical threaded portion to the flat restricted passageway portion. In other words, the tube from end to end has its cross-sections of substantially equal perimeter. The distance between the equidistant walls is preferably between .030 and .060 inch. While this distance may be selected according to the pressure difierential when the liquid pressure is uniform, it has been found advantageous to prepare standard devices as shown in Figures 3 and 4 for water closet flush tanks using tubing with one-half inch outside diameter and one-thirty-second inch walls with this distance of separation about .030 inch so that the device is effective for quietly retarding flows where the pressure differential when the valve is in operation varies from twenty-five to one hundred pounds per square inch. The refilling time when used with the standard. flush tank varies from about seventy-five to around thirty seconds. This device, therefore, permits a quiet refilling within the satisfactory time period under all normal conditions of service.

In practical tests with such devices, however,

,or more for the flat portion of the tube 5 is not compulsory. The coemcient of discharge at eighty-five pounds drop in. pressure from such a device having its walls spaced .030 for a distance of one-quarter of an inch is over 90 percent: with a similar device having the passage one inch long, under like conditions, the coefilcient of flow is less than percent.

It will be noted that the device extends into the tank or receptacle and into the Water which collects in the tank during the refilling period, and that the lower end or orifice is spaced from the walls of the tank so that the Water already present can flow downwardly outside of the tube toward the orifice. The orifice is thus provided by the thin walls of the tube itself at a point where the water already in the tank may meet the water newly issuing through the orifice in a direction substantially parallel to that of the movement of the entering water. This, arrangement has been found of great advantage, especially at high pressure differentials, in reducing noise.

In practice, it is found that such an apparatus operates both during the full flow of refilling and during theshut-ofi? period with such freedom from noise under the various pressure conditions, that the operation is practically inaudible at a distance of a few feet.

While the form shown in Figures 1 and 2 concerns the discharge into a tank at atmospheric pressure, it is also possible to employ a device under conditions where the discharge pressure is considerably above atmospheric. An arrangement capable of operation between the point 01' supply and a control valve is shown in Figure 5, where the supply pipe I2a communicates through the cap 20 with the interior of a conduit 2| of larger section for providing a chamber or receptacle for a body of free water. The upper closing cap 22 connects with the discharge pipe 23. A retarding device I6 of the type shown in Figures 3 and 4 is threaded into the lower cap 20,

so that the water flowing from supply pipe l2a in the device and in the free body of water which creates the necessary pressure to limit the volume of flow through the pipe 23 with the production of a minimum of noise in the device itself or in the system as a whole.

In its preferred form, therefore, the invention comprises an apparatus for supplying a liquid under pressure, a retarding device having at the inlet end a large cross-section, and a gradual transition portion (to avoid vena contracta effects), and a retarding portion having opposite walls providing a flow passage and space between 0.010 and 0.125 of an inch. These walls are preferably parallel and the device is of substantially the same shape and size for a distance of onequarter of an inch or more from the delivery end. Appreciable divergence in the direction of flow tends to cause noise whereas convergence reduces the retarding effect. Preferably, the parallel walls terminate at the orifice which is spaced from the walls of the chamber into which the flow is directed. This shaping of the outlet end portion delivers the liquid in a sheet-like form and retards the flow of liquid into the re= ceptacle with consequent substantial elimination of the noise at the device and in the apparatus as a whole as has been pointed out in detail above.

It is obvious that the illustrative forms of shape and arrangement are not the only ones which can be employed in accordance with this invention, and within the scope of the appended claims.

Having thus described the invention, what we claim as new and desire to secure by Letters Pat cut, is:

1. A device for substantially elminating noise incident to the discharge of liquid under pressure into a receptacle, comprising a conduit having an outlet end discharging into said receptacle and a cylindrical inlet portion adapted to be connected with the pressure line, said cylindrical portion merging by gradual change of shape into a flattened outlet end portion having closely spaced walls, ior retarding the flow of the liquid into the receptacle with consequent substantial elimination of the noise.

2. A device for substantially eliminating noise incident to the discharge of liquid under pressure into a receptacle, comprising a conduit having an outlet end discharging into said receptacle, and a cylindrical inlet end portion adapted to be connected with the pressure line, said cylindrical portion-merging by gradual change of shape into a flattened outlet end portion having the walls thereof spaced apart a distance less than 0.125 inch, for retarding the flow of liquid into the receptacle with consequent substantial elimination of the noise.

3. A device for substantially eliminating. noise incident to the discharge of liquid under pres retarding the flow of the liquid into the receptaclewith consequent substantial elimination of the noise.

4. A device for substantially eliminating noise incident to the discharge of liquid under pressure into a receptacle comprising a tube extending into and discharging into said receptacle, said tube having a straight axis with a cylindrical inlet end portion adapted to be connected with the pressure line, said cylindrical portion merging by gradual change of shape into a flattened outlet end portion, which flattened end portion is of substantially uniform cross-sectional dimensions for a distance in the direction of flow in excess of one-quarter of an inch, the distance between opposed walls of said tube being between 0.010 and 0.060 inch for retarding the flow of liquid into the receptacle with consequent substantial elimination of the noise.

5. A device for substantially eliminating noise incident to the discharge of liquid under pressure into a receptacle comprising a conduit having an outlet end extending into and discharging into said receptacle, and an inlet portion adaptedto be connected with the pressure line, said outlet end portion being shaped so as to provide closely spaced opposed walls which are substantially the same distance apart at all points and from which the liquid is delivered in a sheet-like form, for retarding the flow of the liquid into the receptacle with the consequent substantial elimination of the noise.

6. A device for substantially eliminating noise incident to the discharge of liquid under pressure into a receptacle comprising a conduit having an outlet end extending into and discharging into said receptacle, and an inlet portion adapted to be connected with the pressure line, said outlet end portion being shaped so that one of the dimensions of its cross-section is at least three times the opposite dimension and so that all filaments of the liquid are less than 0.0625 inch from the nearest wall of the conduit, ior retarding the flow of the liquid into the receptacle with consequent sustantlal elimination of the noise.

WALKER F. PETERSON. ALBERT U. WALTER.

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