US2513875A - Thermostatic steam trap - Google Patents

Description

July 4, 1950 H. L. JOHNSON THERMOSTATIC STEAM TRAP Filed June 15, 1945 Ham/d L Job/7500 B) H/SA 7'TORNEYS Patented July 4, 1950 UNITED STATES PATENT OFFI CE THERMOSTATIC STEAM TRAP Harold L. Johnson, Wilkes-Barre, Pa., assignor to W. H. Nicholson & Company, Wilkes-Barre, Pa., a corporation of Pennsylvania Application June 15, 1945, Serial No. 599,579 2 Claims. 01 236-56) This invention relates to thermostatically controlled steam traps. It is an object of the invention to provide an improved trap of the thermostatic type suitable for draining apparatus supplied with steam under high pressure and temperature. In traps of the type described, the thermal unit, unless protected, would be subjected to erosion caused by the impact of high velocity steam, water, particles of dirt, scale and other foreign matter striking directly against the thermal unit. Therefore it is another object of this invention to provide in a trap of the type described means to protect the thermal unit from erosion by impact of scale, dirt, or high velocity steam or water there against. Other objects. and advantages of this inventionwill appear as it is described in connection with, the accompanyin drawing.

In the drawing: v

Fig. 1 is a vertical sectional view of a steam trap in accordance with this invention;

Fig. 2 is a fragmentary vertical sectional view of a modified construction;

Fig. 3 is a view in elevation, looking from the right of the inlet reducing connection shown in section in Fig. 2; and

Figs. 4 and 5 are a view in elevation and a partial view in elevation, respectively of modified constructions of the means for protecting the thermal unit.

A steam trap in accordance with this invention comprises a casing or body I of conventional form, having an inlet opening 2 adapted to be connected to the apparatus to be drained, and an outlet opening 3 suitable for connection to a discharge or drain pipe. Thetop of .the casing l is closed by a cover or cap 4 to which the thermal unit 5 is attached. The thermal unit 5 may be fabricated and charged with temperature-responsive fluid by any of several methods known to the manufacturers of such devices, and inits usual form consists of a convoluted bellows 5a and closing elements 6 at the top and 1 at the bottom, suitably fastened together to form a leakproof envelope or container, such as bysoldering, brazing or welding. The top closing element 6 is provided with a threaded stud 8 for fastening the thermal unit tothe cover 4, and the bottom closing element 1 has a centrally positioned threaded opening 9 for receivingthe stem of a valve In.

Directly beneath the valve ID and in alignment with the coinciding axis of the valve In and the thermal unit 5 is a valve seat H threaded in an opening in the casing I leading to the outlet open 2 ing 3, and provided with a flange l2 of suitable size and shape to permit installation and removal of the valve seat with standard sockettype wrenches.

Surrounding the thermal unit 5 is a cylindrical shield l3 which extends substantially the entire length of the thermal unit, and which is provided at the lower end portion with an inwardly curved flange M which is seated between the flange l2 of valve seat II and a raised boss I 5 in the casing I- The shield I3 is thus centered, fastened and maintained in correct position'by the valve seat I I. The shield I3 extends upward into the cover 4 a sufficient distance to permit only a small circumferential opening [6 between the shield and cover, this opening being of suflicient area to allow the incoming steam easy access to the thermal unit 5, without directly. impinging against the convoluted bellows of this unit, but small enough to exclude dirt, scale and foreign matter of sizes large enough to damage these convolutions.

In the lower end of the shield l3 are located one or more openings ll for permitting the condensate which enters the casing I through inlet 2 to bedischarged through the orifice [8 of valve seat H, and thence to outlet 3. The openings I! are preferably horizontal to avoid direct impingement of the condensate against the thermal unit, and placed low enough in the shield l3, with relation to the valve seat II and inlet 2, so substantially all of the condensate will flow to the outlet 3 by the force of gravity, from the trap, the apparatus it drains and the connecting piping, when the steam supply is shut off. By thus preventing the collection of pockets of water in said apparatus and piping, freezing and its consequent damage is avoided on applications subjected to-low temperature.

The combined total area through the openings I'lis madeto a predetermined lesser area than the orifice l8 through valve seat I I, thereby permitting condensate to be discharged through orifice 18 at a faster rate than it can enter the space I9 formed by the shield I3 around the thermal unit 5, thereby obviating collapse of the thermal unit from contact with a considerable volume of water traveling at high velocity, a condition commonly called water-hammer. The openings 11 are made small enough to exclude from the space I9 dirt, scale, pieces of pipe and gasket of sufficient size to damage the convolutions of the thermal unit 5, or which might lodge between the valve I0 and valve seat ll, causing the trap to become inoperative.

sion. The topand .bottom closingxelements' 6 Where it is desirable to maintain a greater volume of condensate in the casing I for more intermittent trap operation and the danger of freezing is not a consideration the openings 17 may be omitted and the shield be formed with a solid wall as at 45 in Fig. 4 and where it is desirable to screen small particles of dirt, scale, etc. from the condensate the shield may be formed as in Fig. 5'where the wall llis provided with a plurality of small openings 48 extending upwardly in the wall 41 sufiiciently to provide the desired area of opening-and with the Openings small enough to screen out all particles over a permissible size.

To aid in preventing collapse or-the thermal unit 5 from the efiects of water-hammer a, wall or partition is integrally formed with thecasing l between the interior of this casing and the inlet 2. An opening 2| through this partition of a predetermined lesser area than the orifice l8 through the valve seat H permits condensat to be discharged through orifice l8 at a -faster rate thanit can enter-the interior ofcasing I through the opening 2!. The opening 2lis preferably placed. low enough. in partition 29, with relation to the inlet'2 and .valve seat ,so all-of the condensate can fiowto'the outlet 3 by'the force of gravity, :from the apparatus drained and the connectingspiping, when: the steam supply is shut off. .By thus preventing the collectionof pockets of water innsaidrapparatus and piping, freezing and its consequentfdamage is avoided onth'ose applicationsasubjected to low temperature.

Wherethe casing [is not-provided with an integral wall,aas the Wall 2fi of Fig. 1, there may be provided in the inlet [an inlet reducing. connection as the removable fitting :22 shown in Figs 2 and 3. TherfittingiZZ has athreaded end portion :23 adapted to be engaged in thetrap inlet'fi aand. its opposite end 'Of suitable-- shape for engagement with .a wrench a1'i'd-"formedwith a threaded opening 24 for connection to theapparatus 'to be drained. Theopening i25 through the end123 .preferablyawill have a lesser area than the orifice l8 lthroughthe'valve seat "I I, thus permitting condensate to be dischargedthrough the orifice 8 at a faster rate than. it can enter theinterior of easing l'through theopening 25. The top closing element-6 of thermal unit 'iis provided with an inwardly extending hollow cylindrical tubetZfi integral therewith-rand the-bottom closing element 1 is provided with an inwardly extending integral cylindrical stem 21. These parts are machined so stem 12! is av close sliding fitlinside the hollow tubeZB. A shoulder 28 is included on .stem 121. against'swhichthevend of hollow .tu-bel26 abuts when thethermalunit-5 is contracted,'thus limiting the contractionof the thermal unit to a predetermined minimumdimenand l are manufactured and the thermal runitfi is; assembled so that threaded stud'8, hollow tube 26, threaded Opening :9 and cylindrical stemi'! are in alignment axially'at all points between the extreme extended and contracted positions ofithe thermal unit. This vconstruction.prevents fl'exural distortion of the thermal convolutions and insures proper seating '01 the valvetil in' valve'sseat' I I when thermal unit: 5"is extended during operation. Openings?!) in'the hollow tube 1 2.5 and openings 30 in cylindrical stem 21 r. are

"element 6 and the bottom closing element 1 are p10VidGd' i\Vith"fi&t shoulders or steps 42 formed dimensionally parallel to fit standard fiat wrenches.

While the invention has been shown and described in connection with a thermal unit of a particular'zcons'truotion it is to be understood the invention. is equally applicable to thermal units of other types and constructions Where protection of the unit is desirable.

Whatis claimedis: I

'1. line thermostatic steam trap, acas-ing having inlet and *dis'c'harg'e openings, a thermal unit mounted in-said "casingya valve operated by said thermalpnit-and controllingsaid discharge opening, guide means' within said thermal unit rigid with saidcasingp'guide'means cooperating with saidrigid-guide"means'andmoving with the thermal unit to guide said" valve, a seat for said valve mounted in said "d-is charge'open-ing, and shieldi-ng -mea'ns forsai-d thermal unit comprising a metallic cup-shaped member surrounding said thermalunit andhaving its base portion secured to saidcasing'by -saidvalve'--seat, the side wall of --said cup-shaped member being imperforate around said "thermal unit and having drainage holes in the zone adjacent said valve seat.

2. In a thermostatic steam trap, a casing hav ing inlet and discharge openingaa thermal unit mounted in saidca'sing, 'a valve' operated by said thermal u-nitand controlling said discharge opening, guid'e=-means within said thermal unit rigid with said casing, guid'ameahs cooperating with said i' ig i'd gtiidemeans ari'd moving with'thethermal unit'toguide said valve; a seat for said valve mounted in said discharge opening, shielding means for said thermal 'unit i'mmovably secured to said casing by -said" valve 's'eat and' restricting the fiowofflriid to said discharge opening said shielding means having a side wall "formed and positioned "to prevent impingement against said thermal unit of dirt particles.

HAROLD L. JOHNSON.

REFERENCE-S" CITED The"following'references"are of record in the file of this-patent:

llNITED. s'rA'rEs PATENTS lGreatvBritain Mar. 23, 1938

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