US2988101A

US2988101A - Steam traps

Info

Publication number: US2988101A
Application number: US685309A
Authority: US
Inventors: Herman G Mueller
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-09-20
Filing date: 1957-09-20
Publication date: 1961-06-13
Anticipated expiration: 1978-06-13

Description

June 13, 1961 H. G. MUELLER STEAM TRAPS 3 Sheets-Sheet 1 Filed Sept. 20, 1957 INVENTOR.

fifAMA/V 6. 44054451? BY June 13, 1961 H. G. MUELLER STEAM TRAPS 5 Sheets-Sheet 2 Filed Sept. 20, 1957 INVENTOR.

f/fKMA/V 6. M062 4 4 ATTORNEY-S Patented June 13, 1961 2,988,101 STEAM TRAPS Herman G. Mueller, 3245 Wright t., Erie, Pa. Filed Sept. 20, 1957, Ser. No. 685,309 19 Claims. (Cl. 137-483) This invention relates to steam traps.

A purpose of this invention is to provide a steam trap of small overall dimensions comparable in size to that of a standard T pipe fitting of the same pipe size, light in weight, and inexpensive to manufacture, and the design is such that the device is readily machineab le from bar stock of non-corrosive stainless steel or other steels which can be hardened for long life of the seats contained therein.

A further purpose is to provide a trap that will meet the needs of conventional service, closing tightly to prevent steam discharge and opening fully with a large capacity for discharging hot and cold water and for eliminating air when first admitting steam into the trapped system and for maintaining the system free from air and water.

A further purpose is to provide a trap requiring and having no adjustments which may be tampered with and rnisadjusted and which can be designed and manufactured to discharge water at any temperature from that of saturated steam to comparatively cold water.

.A further purpose of this invention is to provide a trap which eliminates pots with covers, upright and inverted buckets, opening and closing discharge orifices which must be changed in diameter and the pots and covers varied in weight and wall thickness and bolting sizes and materials used, for each range of steam pressures and temperatures applied. Such conventional bucket traps are expensive to manufacture, are excessively heavy, and of extremely large size and have a multiplicity of parts and combinations for the range of steam pressures on which they are used.

A further purpose of this invention is to provide a trap without a thermostatically opened and closed orifice which will close with steam and saturated water temperatures but which will open only when the water applied is considerably below saturated steam temperature and which also require adjustment for each range of steam pressure and temperature.

A further purpose of this invention is to provide a trap which closes fully when steam only is applied and an improvement on the so-called impulse traps which have a continuous leakage flow of steam to control their opening and closing and which also require minute adjustments. Such impulse traps operate with two small orifices in series one or both of which are adjustable and both continuously open and through which the continuous leakage flows. The pressure in the intermediate chamber between the orifices varies with steam or water flowing and is used to open and close the main flow. The pressure in the intermediate chamber depends critically on the sharpness or roundness of the orifice entrance edges and their length and the degree of stability or metastability of hot water flowing and flashing into steam.

A further purpose of this invention is to provide a simple trap suitable for production in large quantities and in several sizes for small and large water capacities and any size of which is fixed and nonadjustable for discharging water at any temperature from saturation down and which will operate without changes for any steam or water head pressure and temperature, saturated or superheated and also against any back pressure from a vacuum below atmospheric pressure up to close to the head pressure.

A further purpose of this invention is to provide a trap with a gradually contracting smooth flow passage area, for the steam and the water, to a throat of minimum flow area and then again gradually expanding to produce stable adiabatic flow of the steam or water.

Other objects and features of the invention relating to details of construction and operation will be apparent in the following descriptions and claims.

I have elected to show two of the diiierent forms of my invention, which are practical and etficient in operation and are inexpensive to manufacture and which illustrate the principles involved.

Drawings accompany the disclosure and the various views thereof may be briefly described as:

FIGURE 1, a plan of trap showing the relationship of the passages therein, parts being broken away.

FIGURE 2, a sectional view on line 2-2 of FIGURE 1.

FIGURE 3, a plan of a modification of the design utilizing the same basic principle, parts being broken away.

FIGURE 4, a sectional view on line 4-4l of FIGURE 3,

FIGURE 5, a schematic showing related to a chart to show compartive pressures and areas.

In FIG. 5 is a diagram showing a simplified form of a circular continuous passage from entrance to discharge of the steam or water and shaped like a venturi nozzle with a throat of minimum cross-sectional area near the discharge end and with gradually increasing cross-sectional areas both up stream and down stream from the throat to a maximum of three to four times the throat area. A

small bleed-off connection is shown to a closed chamber transferring the pressure from a point slightly up stream from the throat in the venturi passage to the chamber.

Below the diagram is a chart on which is plotted as abscissa at the bottom, cross-sectional areas in terms of the throat area A. These areas are extended by dot and dash lines to equivalent areas in the chart. Ordinates plotted on the left margin are in terms of the inlet or head pressure P plotted as 1.0. All pressures shown on this chart as well as all pressures referred to in the specifications are absolute pressures not gauge pressures. The curves show the relative theoretical pressures in the passage of FIG. 5 at equivalent areas, and for steam flow, plotted with a dashed lines and for water flow, in solid lines, at various temperatures, expressed in relative pressures at which the water will partially flash into steam in terms of P The uppermost solid curve is for water at steam saturation temperature or for P at 1.0 and the others for flashing pressures at .9P down to .ZP

The principle of a venturi passage as shown in FIG. 5 with a gradually contracting circular cross-sectional area from the initial area to a minimum at the throat and then gradually expanding to the initial area, is commonly used for metering gases and liquids with the discharge pressure closely equal to the initial pressure. In such meters the pressure at the throat is lower than at either end. The pressure drop from initial to the throat is converted into increased velocity at the throat and the increased velocity at the throat reconverted into pressure at the discharge. This is the most accurate form of meter known for liquids or gases as the theoretical values are found to be almost exactly the actual values. With nonflashing liquids which do not change their heat content passing through the meter the pressure drop is measured and converted to velocity by well-known relations and the velocity times the throat area divided by the known specific volume of the liquid gives the flow .rate in pounds per unit of time. Similarly with gases such as steam and hot flashing water for which the physical values of enthalpy, entropy, volume, pressure, temperature and latent heat are well known and published in steam tables the pressure drop taken at constant entropy or adiabatic expansion gives the heat drop which converted into velocity multiplied by the throat area and divided by the volume at the throat gives the rate of flow.

In this invention the same principles employed for a meter are used and an equivalent venturi passage is used. It is formed between the under surface of a flat horizontal 3 circular movable plate with a uniform lift above another flat circular surface on which it can seat. Between these surfaces the steam or water enters near the periphery at a high pressure or head pressure P and flows toward the center of these surfaces where a vertically downward gradually expanding outlet is provided in the lower surface, to a lower outlet pressure or back pressure P Since the flow areas with uniform lift are proportional to the diameters of the flat surfaces at any point, the throat or minimum flow area occurs adjacent the entrance to the outlet hole from Where the flow areas again expand.

When steam is flowing through the passage so formed from P at the periphery to P at the center outlet, it will expand adiabatically as the pressure drops and in conformity with published steam tables and charts, because of the very gradually contracting and expanding flow areas. The velocity at any point in the passage either up stream or down stream from the throat and at the throat, is known to be 223.7 (H H in feet per second where H is the initial enthalpy and H the enthalpy at any assumed pressure down stream and both at the initial entropy. This velocity divided by the specific volume V at the same assumed pressure and initial entropy becomes a maximum, as is well known, when the assumed pressure becomes the critical pressure, which is closely .SSP Since the flow rate must be constant at all down stream pressuresand since the throat is the minimum flow area, the critical pressure must exist at the throat regardless of any P up to .58P By equating the flow rate at the throat so calculated to the flow rate at any other pressure above and below the throat pressure, the flow area at which the assumed pressure must exist is readily obtained. By this method the flow area relative to the throat area for all pressure between P and P were obtained for the dashed steam curve in FIG. 5.

When water at steam temperature is flowing the same method is used. In this case, however, the velocity divided by the specific volume becomes maximum at about .9751, and this pressure must exist at the throat.

When water below steam temperature is flowing, the enthalpy and specific volume remain constant until the pressure drops to a value where part of the water begins to flash into steam. The velocity down to this pressure is due to the pressure drop only and as is well known is 12.2 (P feet per second with P and P in p.s.i. Again the velocity divided by the specific volume becomes a maximum at the flash pressure and therefore must be the pressure at the throat. By this method the solid water lines in FIG. 5 were obtained.

It thus becomes apparent that the throat pressures and those upstream from the throat are not affected by the back pressure P unless it exceeds .58P for steam flow, .975P for water at saturated temperature or the flash pressures for water of lower temperatures. The action of this invention is therefore not sensitive to the back pressure and can be used without change with back pressures up to about .70P

Due to the gradual contraction and expansion of the passage the flow is stable throughout the passage and the actual pressures as found from experimental results agree closely with those calculated by the above methods.

Referring to the embodiment shown in FIGS. 1 and 2, a main body has an inlet 12 with two branch inlets l4 and 16 which form a Y-shaped passage. Inlet 12 is provided with a pipe tap 18 which connects with a standard inlet pipe.

An outlet passage 20 is drilled in the opposite side of the body 10 formed with a tapped section 22. The inlet and outlet may be standard threaded pipe connections, or drilled for welded pipe connections or flanged for high pressure steam and water in which case a cast or forged body is used instead of making the body of bar stock stainless or other steels.

Rising upwardly from passage 12 and from the ends of

passages

14 and 16 are ferruled

openings

24, 26 and 28. These ferrules have a press fit in the body or may as shown at 70.

4 be screwed into the body; and in any case, the top surfaces 30 are ground simultaneously and flush with the top face 32 of the body 10, which is also surface ground. The body and ferrules are hardened to provide a long life. Three ferrules is the preferred number but more may be used, equally spaced on a circle concentric with the center and each fed by a passage similar to

inlets

14 and 16.

A shallow annular relief groove 34, only a few thousandths of an inch deep, is machined into the top face 32 of the body having an outside diameter just outside the concentrically located ferrule openings and an inside diameter just inside the ferrule openings, as shown in FIGS. 1 and 2.

Centrally of the body is a passage 36 having a slight taper 38 at the top and joining with the exit passage 20. The axes of

openings

24, 26, 28 are parallel to the axis of passage 36. Also in the body are three angled passages 40 extending upwardly from the center passage 36 to a point within the relief 34, but between the

ferrule openings

24, 26 and 28.

On the top of the square body 10 is a square cover plate 50 having a circular bore 52 adjacent its bottom surface and a smaller bore 54 penetrating more deeply into the cover. The edge of the ground face 32 on the body 18 matches with a ground surface 56 on the cover 50, and the cover is held in place by four bolt head screws 53.

Within the cover 50 and on top of the housing 10 is a cylindrical relatively thin plate 60, positioned for movement up and down in bore 52. This plate is hardened and surface ground on both faces. Its outside diameter 62 is dimensioned so that its periphery will form a seat on surface 32 of the body 10 just outside of the relief groove 34 and also to allow a peripheral clearance 64 in the bore 52 and leaving the plate free to lift from the seating face 32 until its upper face seats on surface 66 at the top of the bore 52. To form a relatively narrow seat 68 at this point, the top face of the plate 60 is turned down at its periphery about one quarter of its thickness The smaller bore 54 forms a chamber 72 which serves as a control chamber.

The bottom face of the plate 60, together with the top face 32 of the body 10, thus forms the venturi passage in FIG. 5. The steam and water enter this passage through the

ferrules

24, 26 and 28 near the periphery where the passage area is largest and flows to the minimum diameter and area or throat 82 near the center and at the periphery of the tapered or beveled surface 38 at the top of passage 36. At the center of plate 60 is an inverted conically shaped deflector 84 riveted in place and so shaped that the passage areas 86 downstream from throat 82 gradually increase to that of the area of outlet passage 20.

The steam or water passing through the venturi is traveling at high velocities and is deflected by deflector 84 through a 90 angle into the center passage 36, thus generating vertically upward reaction components acting on deflector 84 and plate 60. A ring of small holes 90 are drilled in circumferentially spaced relation around deflector 84 in plate 60 having a combined minimum area of two to three times that of the area of the peripheral clearance 64 around the plate.

These holes are counterbored and are equally spaced on a circle having a diameter 1.4 to 1.5 that of the diameter of the throat of the unit at the deflector 84 shown diagrammatically at 82 in FIG. 5. When the plate 6n seats on surface 32, these holes are sealed, and this, together with the contact of plate 60 with groove 34 at its periphery, seals olf chamber 72.

Before describing the complete operation of the unit, I will describe a second embodiment shown in FIGS. 3 and 4. Similar reference characters are used on similar parts and passages. In FIG. 4, it will be seen that the top cover 50 is the same as in FIG. 2, together with the plate 60. The body of the unit has an entrance 101, which leads up through a passage 102 to an annular passage 104 in an intermediate body 106. The intermediate body has a central passage 108 with a tapered top edge portion 110.

This body also has a ground face 112 provided with an outer annular face groove 114 and an inner annular face groove 116, spaced from each other.

These face grooves are connected by radial passages 120 passing through the body 106 and having risers 122 which connect into the groove sections. Also in the top face of plate 106 is an annular groove 130 which is machined deeper into the body than the two relatively shallow grooves 114 and 116.

The annular groove 130 is connected to the annular port 104 by spaced holes 132. The intermediate body 106 is sealed to the body 100 by

circular gaskets

134 and 136. The operation of the device is as follows:

When the summation of the products of the pressures shown by the curves in FIG. 5 multiplied by the annular areas on the under side of the plate on which they act upwardly, plus the vertical upward component of the reactions on deflector 84, is preponderant over the summation of the products of the pressures on top of the plate times the annular areas on which they act downwardly, the plate 60 will lift up against the upper seat 68. Conversely, when the preponderance is downward, the plate will seat on surface 32. When the plate 60 is. seated on the upper seat and steam or water is flowing through venturi passage 80, the pressure in chamber 72 will equal the pressure in the venturi passage at the diameter of the circle on which the holes 90 have been drilled.

The vertical upward component of the reaction on deflector 84, due to the 90 turn of the flow at a high velocity, is, as is well known, in pounds force equal to the flow in pounds per second times the velocity in feet per second divided by g. With steam flowing the velocity is comparatively high, but the rate of flow very small compared to water flow. With water flowing and either flashing or not flashing the rate of flow is many times that of steam, but the velocities considerably lower. The result is a preponderant reaction component with water flowing over that of steam flowing whenever the flash pressure of the water is .7P or lower. The reactions, therefore, assist the plate to lift whenever water is flowing with a wide range of water temperatures commonly existing in steam systems to be drained.

The reactions of the steam or water entering under the periphery of the plate and turning 90 into the venturi passage 80 are found to be negligible due to the absence of any appreciable pressure drop and very small velocities.

As an example a trap with standard three-quarter inch pipe inlet and outlet produced very satisfactory results with the following dimensions:

Plate diameter 1.420 inches.

Seat 68 diameter 1.00 inches outside;

.90 inches inside.

Throat diameter .40 inches.

Diameter circle holes 90 .56 to .60 inches.

Diameter of ferrules .28 inches outside; .18 inches inside.

Plate lift .035 inches.

A trap embodying my invention having a gradually contracting smooth flow passage area, for the steam and water, to a throat of minimum flow area and then again gradually expanding produces stable adiabatic flow of the steam or water.

I have found that designs based on the foregoing, work out quite satisfactorily in actual traps about as follows:

With steam flow the downward preponderance be comes effective instantly as soon as the plate begins to lift and reseats it very quickly and before it reaches full lift. The amount of steam discharged with each lift is 6 extremely small and negligible. When hot water at satu ration temperature is applied, the preponderance of upward force to lift the plate is small but enough to raise it against the upper stop 68. As water at lower temperatures is applied the reactions increase and the preponderance of lifting force increases rapidly and snaps the plate open forcefully and holds it open until all the water available is discharged and steam is again applied whereupon the plate snaps shut.

The effects of back pressure P on the functioning of this invention can be calculated by extending the aforementioned theories.

When steam is flowing there is no change in the rate of flow for any P of .58P or less. Up to this P the pressures under the plate from its periphery to the throat remain therefore the same. Since the projected area of the deflector 84 and the plate up to the throat is only about 7 to 8% of the total plate area, the effect of rising P on this small area is insuflicient to overcome the preponderance of the downward seating force. As P rises to greater values than .58P the throat pressure rises with it and spreads the effective area on which it acts, thereby appreciatively increasing the upward force. However, at the same time, the upward reactions diminish thereby again reducing the upward force. The net result is that the downward force will remain preponderant and in part due to a rising pressure in the control chamber 72, until the P exceeds about .7P

When water is flowing, there is again no change in the rate of flow for any P up to the flash pressure and again all pressures under the plate from its periphery to the throat remain the same for all P to the flash pressure. The effect of rising P to the flash pressure will act only on the small area of the plate inside the throat diameter but this will increase the upward preponderance and be helpful in lifting the plate and holding it open for water flow. If the P rises above the flash pressure, it will further assist the upward preponderance and be still further helpful and until it reaches the circle of holes whereupon it will reduce the upward preponderance by reason of increasing the pressure in control chamber 72.

The net result with water flowing is that the plate will stay lifted and the trap open and with any water temperatures from saturation down and with P very nearly equal to P The maximum P at which the invention will operate satisfactorily is therefore governed by steam flow and at about .7P

Since the plate remains open as long as water is flowing, and will seat and close as soon as the water is exhausted and steam again flows, it must open intermittently with steam applied to test the system for the presence of steam, Water or both.

This cycle functions as follows:

Starting the cycle assuming that the plate has just seated on 32 and closed due to steam flow, the steam pressure in chamber 72 which is now extended to the plate periphery since seat 68 is open, and with holes 90 on a circle 1.4 to 1.5 times the diameter of the throat, will be about .88P to .90P as shown by dashed lines for steam in FIG. 5. This pressure in chamber 72 is sealed when the plate seats on surface 32 because the holes 90 are then closed and the periphery of the plate also seats on surface 32, thus closing the chamber 72 and sealing the pressure contained therein.

When the plate seats on surface 32, it also seals and shuts off the steam flow from

ferrules

24, 26 and 28 in FIGS. 1 and 2 or from the groove 130 in FIGS. 3 and 4. The pressure in relief 34 of FIGS. 1 and 2 is then immediately drained through holes 40 to the back pressure P in hole 36. Similarly the pressure in reliefs 114 and 116 of FIGS. 3 and 4 is then immediately drained through

holes

122 and 120 to the back pressure P in hole 108. The pressure remaining between the underside of the plate and that portion of the surface on which it seats from relief 34 in FIGS. 1 and 2 and relief 116 in FIGS. 3 and 4, to the throat, will also escape to the back pressure, either inwardly through the throat or outwardly through the reliefs. A small area around each hole 90 into which the pressure in chamber 72 may penetrate will continue to hold this pressure.

The upward pressure under the plate is thus reduced to P over about 91% of its area. The balance of about 9% is acted upon upwardly by P in the ferrules of FIGS. 1 and 2 or in the groove 130 of FIGS. 3 and 4 plus a portion of the seats of the ferrules and on either side of groove 130, into which P may penetrate, This penetration area is included in the 9% of the plate area. It also includes the area of the holes 90 and a small penetration area around each hole into which the pressure in chamber 72 may penetrate. Thus, the downward preponderance of force is suddenly greatly increased just after the plate seats and the drain off completed, and the sealing off of P and the pressure in chamber 72 is made more secure due to the increased pressure on the seats sealing them off.

The pressure in chamber 72 then slowly diminishes or dissipates due to condensation caused by radiation from the exterior of the cover 50 and by a minute leakage through the peripheral seat of the plate and through the holes 90. As the pressure in chamber 72 diminishes, the downward preponderance of force also diminishes until it reduces to zero which will take place when this pressure becomes about .091 plus .9lP The plate will then again lift against stop 68, and the flow of steam or water will again begin reestablishing the flow pressures under the plate and in venturi passage 80 and also the pressure in chamber 72 through holes 96. If upon opening, water has accumulated in the system and flows through the venturi, the plate will remain open. If upon opening, the steam flows through the venturi, the plate will immediately again close and repeat the cycle.

Holes 40 of FIGS. 1 and 2 have their equivalent in

holes

120 and 122 of FIGS. 3 and 4 and similarly surface 32 compares with surface 112. Also relief groove 34 of the FIGS. 1 and 2 serves as grooves 114 and 116 of FIGS. 3 and 4.

If the system to be drained remains free of water for an extended period, as may be the case with superheated steam systems, or whenever little moisture condenses, the plate will pop open for a minute fraction of a second at equal intervals governed by the time it takes for the pressure in chamber 72 to dissipate from steam flowing pressure in this chamber of about .88P to .90P given above, to the zero preponderance pressure when the plate is seated of .09P plus .9lP also given above. If P is high compared to p the period of the cycle will be shorter. If P is high compared to P the period of the cycle will be longer. The period will also be affected by the rate of condensation in chamber 72 and the tightness of the seats.

Experience has demonstrated that this period will be from about 20 seconds minimum to about 2 or 3 minutes maximum. The length of the period is unimportant as the steam loss with steam only present in the system is negligible. The water capacity of the trap is not affected since in the presence of large quantities of water in the system, the trap stays open as long as water is present;

It is important that during the instant of lifting or seating of the plate that the pressures above and below the plate remain constant, to avoid stalling or so called dribbling. In this invention with a venturi passage formed by a stationary surface 32 and the under side of the plate 60, the flow areas have the same relative proportions at all lifts from zero to full assuming uniform lift across all diameters. If the flow areas in the venturi passage retain constant relative proportions throughout the lift the pressures at any point will also remain constant.

To insure uniform lift of the plate the pressures under the plate emerging from each ferrule in FIGS. 1 and 2- or around groove 130 in FIGS. 3 and 4 must be equal. This will be the case and is readily accomplished by providing ample areas of flow in the

holes

24, 26 and 28 of FIGS. 1 and 2 and in the distribution annular chamber 104 of FIGS. 3 and 4, which will thereby supply uniform pressures to each ferrule or to each hole 132 to the groove 130.

Also, to insure a constant pressure over the plate during the lifting or seating instant and during which instant the seat 68 is open and will allow steam or water to flow through clearance 64 at the periphery of the plate, from the higher pressure at the entrance to the venturi to the lower pressure in chamber 72 supplied through holes from a circle near the throat of the venturi, the follow ing instantaneous actions should be given consideration. When steam is flowing and the preponderant force is dc sired downward to close the plate, any increase in pressure in chamber 72 is helpful and desirable.

When water is flowing, however, the preponderant force is desired upward to open the plate and any increase in the pressure in chamber 72 would be a disadvantage, since it would reduce the upward preponderance. The action of the vapor flow of steam is very quick and almost instantaneous whereas with water, due to its greater weight, the action is much slower.

To insure an approximately constant pressure in chamber '72 during the lifting instant when water is flowing, it has been found essential to provide, as stated above, a minimum area in holes 90 of two to three times the area of clearance 64 around the plate so that the pressure in chamber 72 is predominately governed by that supplied through holes 90 and not by that which could instantly flow through clearance 64. This area in holes 90 has been found to insure ample upward preponderance when water is flowing to open the trap and at the same time improve the downward preponderance when steam is flowing which accounts for the quick closing before reaching full lift. When water is flowing and the plate seats on stop 68, any flow around the plate periphery is, of course, stopped.

What is claimed is as follows:

1. A steam trap comprising a body having a generally fluid-tight cavity therein, means defining an inlet to the periphery of said cavity, means defining an outlet passage extending generally from the center of said cavity, whereby fluid may flow from said inlet radially inwardly of said cavity to said outlet passage, a plate movable in said cavity, said plate having an opening therethrough, said body having a first seat against which said plate may be moved to prevent flow of fluid from the periphery of said cavity to said outlet passage, and from one side of said plate to the other through said opening in said plate, said body having a second seat against which said plate may be moved to permit the flow of fluid to said outlet passage, said plate when seated against said second seat dividing said cavity into a first chamber on one side of said plate and a second chamber on the other side of said plate. adjacent said outlet passage, said first chamber being isolated from said second chamber except for said opening in said plate, the surface of said plate adjacent said outlet passage cooperating with portions of said body surrounding said outlet passage to define a converging area in said second chamberhaving its minimum area adjacent to the end of said outlet passage which is nearest the second chamber.

2. A steam trap comprising a body having a generally plate may be moved to prevent flow of fluid from the periphery of said cavity to said outlet passage, and from one side of said plate to the other through the openings in said plate, said body having a second seat against which said plate may be moved to permit the flow of fluid to said outlet passage, said plate when seated against said second seat dividing said cavity into a first chamber on one side of said plate and a second chamber on the other side of said plate adjacent said outlet passage, the surface of said plate adjacent said outlet passage cooperating with portions of said body and the end of said outlet passage nearest said plate to define a converging area toward said outlet passage when the plate is seated against said second seat in such a manner that said inlet passages, said second chamber, and said outlet passage define a venturi wherein the throat of the venturi is adjacent to the end of said outlet passage which is nearest the second chamber.

3. The combination set forth in claim 2 wherein said inlet passages have their axes generally parallel to the axis of said outlet passage,

4. A steam trap comprising a body having a generally fluid-tight cylindrical cavity therein, said body having a plurality of inlet passages communicating with the periphery of said cavity, said body having an outlet passage extending generally axially of said cavity, whereby fluid may flow from said inlet passages generally radially inwardly of said cavity to said outlet passage, a generally circular plate of substantially uniform thickness movable in said cavity, said plate having a plurality of openings therethrough, said body having a first seat in the end of said cavity adjacent said outlet passage against which said plate may be moved to prevent flow of fluid from the periphery of said cavity to said outlet passage, and from one side of said plate to the other through the openings in said plate, said body having an annular groove in the wall of said cavity defining a second seat against which said plate may be moved to permit the flow of fluid to said outlet passage, said plate when seated against said second seat dividing said cavity into a first generally cylindrical chamber on one side of said plate and a second generally cylindrical chamber on the other side of said plate adjacent said outlet passage, the surface of said plate adjacent said outlet passage cooperating with portions of said body and the end of said outlet passage nearest said plate to define a converging area toward said outlet passage when the plate is seated against said second seat in such a manner that said inlet passages, said second chamber and said outlet passage define a venturi wherein the throat of the venturi is adjacent to the end of said outlet passage which is nearest the second chamber.

5. The combination set forth in claim 4 wherein said body includes an inlet opening, means in said body providing communication between said inlet opening and said inlet passages, said body including an outlet opening communicating with said outlet passage, the axis of said inlet opening being in alignment with the axis of said outlet opening.

6. The combination set forth in claim 4 wherein said body includes relief passages providing communication between said second chamber and said outlet passage.

7. The combination set forth in claim 6 wherein said body includes relief grooves in the face of said body which forms the end of said second chamber, which is adjacent said outlet passage, said grooves communicating with said relief passages.

8. The combination set forth in claim 4 wherein said openings in said plate lie on a circle having a diameter 1.4 to 1.5 times the diameter of the throat of said venturi, said first seat having seat portions positioned in the same manner as said openings to close said openings when the plate is seated on said first seat.

9. A steam trap comprising a body having a generally cylindrical fluid-tight cavity therein, said body havinginlet passages in the portion thereof which forms one end face of said cavity, said passages being spaced about the periphery of said cavity and extending generally axially of said cavity, an outlet passage in said portion of said body generally centrally of said cavity, said body having an inlet opening and an outlet opening, said body having an annular passage therein communicating with said inlet opening, the axis of said annular passage being aligned with the axis of said cylindrical cavity, said inlet passages communicating with said annular passage, said outlet opening communicating with said outlet passage, whereby fluid may flow from said inlet opening through said annular passage and said inlet passages to said cavity and from said cavity through said outlet passage to said outlet opening, and a generally circular plate of substantially uniform, thickness movable in said cavity, said plate having a plurality of openings therethrough, said portion of said body which forms the end of said cavity providing a first seat against which said plate may be moved to prevent the flow of fluid from the periphery of said cavity to said outlet passage and from one side of the plate to the other through said openings in said plate, said body having a second seat comprising an annular groove around the side of said cavity against which said plate may be moved to permit the flow of fluid to said outlet passage, said plate when seated against said second seat dividing said cavity into a first chamber on one side of said plate and a second chamber on the other side of said plate adjacent said outlet passage, said plate having means thereon cooperating with portions of said body when said plate is seated against said second seat to provide a converging area in said second chamber toward the end of said outlet passage which is adjacent said plate.

10. The combination set forth in claim 9 including a first annular groove in the portion of the body forming the end face of said cavity, said inlet passages lying on a circle, the diameter of said first annular groove being greater than the diameter of said circle on which said inlet passages lie.

11. The combination set forth in claim 9 including a first annular groove in the portion of the body forming the end face of said cavity, said inlet passages lying on a circle, the diameter of said first annular groove being greater than the diameter of said circle on which said inlet passages lie, a second annular groove concentric with said first groove and having a diameter less than the diameter of the circle on which said inlet passages lie, and relief passages extending from said outlet passage to said first and second annular grooves.

12. A steam trap comprising a body having a generally fluid-tight cylindrical cavity therein, said body having a plurality of inlet passages communicating with the periphery of said cavity, said body having an outlet passage extending generally axially of said cavity, whereby fluid may flow from said inlet passages generally radially inwardly of said cavity to said outlet passage, a generally circular plate of substantially uniform thickness movable in said cavity, said plate having a plurality of openings therethrough, said body having a first seat in the end of said cavity adjacent said outlet passage against which said plate may be moved to prevent flow of fluid from the periphery of said cavity to said outlet passage, and from one side of said plate to the other through the openings in said plate, said body having an annular groove in the Wall of said cavity defining a second seat against which said plate may be moved to permit the flow of fluid to said outlet passage, said plate when seated against said second seat dividing said cavity into a first generally cylindrical chamber on one side of said plate and a second generally cylindrical chamber on the other side of said plate adjacent said outlet passage, the flow area; of said second chamber when said plate is seated against said second seat being such that said inlet passages, said second chamber and said outlet passage define a venturi wherein the throat of the venturi is adjacent to the end of said outlet passage which is nearest the second chamber, and a tapered deflector on said plate projecting axially into the outlet passage, the end of said outlet passage nearest said second chamber being tapered, the area between the surfaces of said deflector and the sides of said outlet passage being such as to provide a gradually increasing flow area between the second chamber and the outlet passage in the direction of the outlet passage.

13. A steam trap comprising a body having a generally cylindrical fluid-tight cavity therein, said body having inlet passages in the portion thereof which forms one end face of said cavity, said passages being spaced about the periphery of said cavity and extending generally axially of said cavity, an outlet passage in said portion of said body generally centrally of said cavity, said body having an inlet opening and an outlet opening, said outlet opening communcating with said outlet passage, whereby fluid may flow from said inlet opening through said inlet passages to said cavity and from said cavity through said outlet passage to said outlet opening, and a generally circular plate of substantially uniform thickness movable in said cavity, said plate having a plurality of openings therethrough, said portion of said body which forms the end of said cavity providing a first seat against which said plate may be moved to prevent the flow of fluid from the periphery of said cavity to said outlet passage and from one side of the plate to the other through said openings in said plate, said body having a second seat comprising an annular groove around the side of said cavity against which said plate may be moved to permit the flow of fluid to said outlet passage, said plate when seated against said second seat dividing said cavity into a first chamber on one side of said plate and a second chamber on the other side of said plate adjacent said outlet passage, and a tapered deflector on said plate projecting axially into the outlet passage, the end of said outlet passage nearest said second chamber being tapered, the area between the surfaces of said deflector and the sides of said outlet passage being such as to provide a gradualy increasing flow area between the second chamber and the outlet passage in the direction of the outlet passage.

14. A steam trap comprising a body including a first section and a second section, said first section having a generally cylindrical open-ended cavity therein, means for fixing said first and second sections together, said first and second sections combine to provide a generally cylindrical fluid-tight cavity, said second section providing an end face for closing the open end of said cavity in said first section, said second section having a plurality of circumferentially spaced inlet passages in the end face thereof forming the end of said cavity and communicating with said cavity, said second section having an outlet passage generally centrally of said cavity, said section having an annular groove adjacent the open end of said cavity therein, a plate movable in said cavity, said plate having an opening therethrough, said end face of said body providing a first scat against which said plate may be moved to prevent flow of fluid from the periph cry of said cavity to said outlet passage from one side of said plate to the other through said opening in said plate, said annular groove in said first section forming a second seat against which said plate may be moved to permit the flow of fluid to said outlet passage, said plate when seated against said second seat dividing said cavity into a first chamber on one side of said plate and a second chamber on the other side of said plate adjacent said outlet passage, and a tapered deflector on said plate projecting axially into the outlet passage, the end of said outlet passage nearest said second chamber being tapered, the area between the surfaces of said deflector and the sides of said outlet passage being such as to provide a gradually increasing flow area between the second chamber and the outlet passage in the direction of the outlet passage.

15. A steam trap comprising a body having a fluid tight cavity therein, means defining an inlet to said cavity, means defining an outlet from said cavity, a member mo'vably mounted in said cavity, said member having openings therethrough, said body having a first seat against which said member may be moved to prevent flow of fluid from the inlet to the outlet, and from one side of said member to the other side of said member, said body having a second seat against which said member may be moved to permit the flow of fluid to said outlet, said member when seated against said second seat cooperating with the sides of said cavity to define a converging passageway from said inlet, a threat, and a diverging passageway from said throat to said outlet, said member when seated against said second seat further defining a chamber isolated from said converging area except for the openings in said member.

16. A steam trap comprising a body having a fluid tight cavity therein, means defining an inlet to said cavity, means defining an outlet from said cavity, a member movably mounted in said cavity, said member having openings therethro'ugh, said member being movable in response to pressures from a first position wherein said member cuts off the flow from said inlet to the outlet and through said openings to a second position wherein said member cooperates with said cavity to define a converging passageway from said inlet, a throat, and a diverging passageway from said throat to said outlet, said member in said second position defining a chamber which is isolated from said converging area except for the openings through said member.

17. The combination set forth in claim 16 wherein a side clearance is provided between the periphery of said member and said cavity, the total flow area of said openings in said member being two to three times the flow area between the periphery of said member inside of said cavity.

18. The combination set forth in claim 16 wherein said openings in said member are counterbored, the larger cross section of the counterbore being adjacent the chamber.

19. A steam trap comprising a body having a gen erally cylindrical fluid tight cavity therein, said body having inlet passages in the portion thereof which forms one end face of said cavity, said passages being spaced about the periphery of said cavity and extending generally axially of said cavity, an outlet passage in said portion of said body generally centrally of said cavity, said body having an inlet opening and an outlet opening, said outlet opening communicating with said outlet passage, whereby fluid may flow from said inlet opening through said inlet passages to said cavity and from said cavity through said outlet passage to said outlet opening, and a generally circular plate of substantially uniform thickness movable in said cavity, said plate having a plurality groove around the side of said cavity, one wall of said: groove forming a second seat against which said plate may be moved to permit the flow of fluid to said outlet passage, said plate when seated against said second seat dividing said cavity into a first chamber on one side of said plate and a second chamber on the other side of said plate adjacent said outlet passage, said plate hav-. ing means thereon cooperating with portions of said body when said plate is seated against said second seat to.

provide a converging area in said second chamber toward the end of said outlet passage which is adjacent said 13 14 plate, said body having an annular groove in the portion References Cited in the file of this patent thereof forming an end face of the cavity, said groove U ITED TAT]; FATE T having a radial width slightly greater than the width of N S N S said inlet passages and intersecting said inlet passages, and 2*2341387 Schott 1941 relief passages extending between said outlet passages 6 2'634744 Wells APr'14'1953 and said annular groove 2,817,353 Midgette Dec. 24, 1957