CA1122500A - Steam traps - Google Patents

Steam traps

Info

Publication number
CA1122500A
CA1122500A CA344,130A CA344130A CA1122500A CA 1122500 A CA1122500 A CA 1122500A CA 344130 A CA344130 A CA 344130A CA 1122500 A CA1122500 A CA 1122500A
Authority
CA
Canada
Prior art keywords
trap
housing
steam
interior
thermostatic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA344,130A
Other languages
French (fr)
Inventor
Alan F. Bennett
Edward R.C. Clayton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Spirax Sarco Ltd
Original Assignee
Spirax Sarco Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Spirax Sarco Ltd filed Critical Spirax Sarco Ltd
Application granted granted Critical
Publication of CA1122500A publication Critical patent/CA1122500A/en
Expired legal-status Critical Current

Links

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16TSTEAM TRAPS OR LIKE APPARATUS FOR DRAINING-OFF LIQUIDS FROM ENCLOSURES PREDOMINANTLY CONTAINING GASES OR VAPOURS
    • F16T1/00Steam traps or like apparatus for draining-off liquids from enclosures predominantly containing gases or vapours, e.g. gas lines, steam lines, containers
    • F16T1/02Steam traps or like apparatus for draining-off liquids from enclosures predominantly containing gases or vapours, e.g. gas lines, steam lines, containers with valves controlled thermally
    • F16T1/10Steam traps or like apparatus for draining-off liquids from enclosures predominantly containing gases or vapours, e.g. gas lines, steam lines, containers with valves controlled thermally by thermally-expansible liquids

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Temperature-Responsive Valves (AREA)
  • Safety Valves (AREA)
  • Accommodation For Nursing Or Treatment Tables (AREA)
  • Sampling And Sample Adjustment (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Abstract

ABSTRACT
A thermostatic steam trap having a balanced pressure thermostatic element (2,2A,2B) operated by volatile fluid (15) is disclosed in which an internal void (10) of the element is open to steam/condensate within the trap, and in which the volatile fluid fills a housing (6) outside the element when the trap is fully open thereby to support the element against high pressure within the element. In the trap fully-closed condition the element adopts a nearly nesting condition so that if the element is then subjected to higher pressure externally it adopts a fully nesting condition in which it can withstand great external pressure.

Description

~lZ~

STEAM TRAPS
This invention xelates to steam traps.
The invention is particularly concerned with thermostatic steam traps having a so-called "balanced pressure" thermostatic element which in one type of trap takes the form of a sealed bellows with a rigid metal top and bottom, but with a side wall wh`ich will lengthen or shorten if the rigid ends are pulled apart or pushed together. The rigid top is fast with the body of the trap whilst the rigid bottom carries the valve member of the trap. The bellows is filled with a volatile fluid.
In operation this fluid is heated by condensate present in the trap such that at a condensate temperature at or above a predetermined temperature t below the saturated steam temperature corresponding to the pressure at the trap, the bellows ls sufficiently expanded for the valve member to be seated on its seat to close the trap. At condensate temperatures below t the bellows is collapsed and the trap is open.
An aspect of the invention is as follows:
A thermostatic steam trap comprising a base;
a cover mounted on the base r the base and cover defining a hollow interior of the trap; a casing within said interior fast with the base and cover; a housing movably mounted in the casing; resilient means urging the housing J 25 to seat in the casing; a balanced pressure thermostatic element mounted in the housing; a valve member carried by the thermostatic element; an inlet port to said '~

11~22SOEO

interior' an outlet port from said interior; and a valve seat in the outlet port; the casing locating the housing and the thermostatic element with respect to the outlet port so that the valve member carried by the thermostatic element co-operates with the valve seat in the outlet port for opening and closing the trap; the element defining an internal void that is open to steam/condensate within the trap and that is sealed from the interior of the housing in which the element is mounted; the housing having its interior sealed from said interior of the trap and containing volatile fluid which entirely fills the housing outside the element when the trap is fully open thereby to support the element; the element being moved by the pressure exerted by the volatile fluid upon heating of the fluid to urge the valve member carried by the element on to the valve seat to close the trap with the element, in the trap fully-closed condition, being in a nearly nesting condition; the housing moving away from its seating condition in the casing, against the action of said resilient means; to permit the element to adopt a fully nesting condition if further heating of the volatile fluid occurs. The thermostatic element may be a bellows or a multi-diaphragm arrangement. In such a trap the thermostatic element has a fast, positive response to temperature and pressure changes but can withstand severe over-pressurisation due either to water-hammer or superheat, either of which conditions may occur in a steam system. In the case of waterhammer, during which high hydraulic pressure can be generated inside the element, the element is supported against deformation by the volatile fluid. If super-heating occurs causing the volatile fluid to generate high pressure outside the element, the element fully nests in which condition it can withstand great pressure.
` 35 For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the ~1~2Z5~0 2a accompanying drawings, in which:-Figure 1 is a somewhat diagrammatic sectionalside view of part of a steam trap, and Figures 2A and 2B are similar views of the major parts of two further forms of steam trap.
The steam traps shown in the Figures are balanced pressure thermostatic traps having a ~ase which carries the thermostatic element of the trap. In the trap of Figure 1 this element is in the form of a bellows 2 having rigid end walls 3 and 4 ana a side wall 5 that can shorten or lengthen. The bellows 2 is disposed within a housing 6 with its lower end wall 3 fast with a bottom wall 7 of the housing 6. The upper end wall 4 is free to move up and down in the housing 6.
The housing 6 is disposed within a casing 8 .. . .

11~25¢~0 that is mounted on a spigot lA on the base 1, the housing 6 being held against a flange 8A of the casing 8 by an overload spring 9 acting between a further flange 8B of the casing 8 and a flange 6A of the housing 6.
The interior void 10 of the bellows 2 is open to the casing 8 below the flange 8A via an aperture 11 in the housing wall 7, the connection between the bellows end wall 3 and the housing wall 7 sealing the inte~ior of the housing 6 (outside the bellows 2) from the casing 8. Below the aperture 11 there is a valve-seat 12, formed in the spigot lA, on which can seat a valve member 13 that is carried by a stem, 14 depending from the upper bellows wall ~ and extending throu~h the aperture 11 so that the v~lve member 13 moves with the upper wall 4.
The interior of the housing 6, outside the bellows 2, is filled with volatile fluid 15.
The casing 8 is contained within a cover 18 that is mounted on the base 1 so that the interior of the trap is sealed from the atmosphere. Ports 16 in the casing 8 below the flange 8A place the interior of this part of the casing 8 in communication with the interior of the cover 18.
In service the trap is mounted in a steam flow line'~vith a port 19 in the base l in connection with the flow line. In operation, before steam is turned on, the trap adopts the condition shown in Figure 1-b,ellows
2 expanded, valve 12/13 open, housing 6 seated on flange 8A. When the steam is first turned on condensate passes through the port 19 into the interior of the cover 18 and, via the ports 16, out ~--through the port 17 at the valve seat 12. As warmer condensate reaches the trap,heat is transmitted to the volatile fluid 15 which expands with the result that the bellows 2 begins to be forced to c~llapse thereby moving the valve member 13 closer to the valve seat 12.
At a predetermined temperature t below the saturated ~Ll steam temperature corresponding to the pressure at the trap, the volatile fluid 15 boils and begins to exert vapour pressure. When the inside of the bellows 2 is at steam pressure, the outside, because of the termperature head, is at a pressure which is higher by an amount p. This excess pressure forces the bellows 2 to collapse further and hence forces the valve member 13 down onto its seat 12. Thus the trap closes just before steam temperature is reached. Condensate is then held up in the trap until it has cooled to the temperature t below steam temperature. At this point the vapour pressure in the housing 6 is less than the steam pressure inside the bellows 2 so that the bellows 2 is able to expand again and the valve member 13 therefore lifts off the valve seat 12.
The volatile fluid can be a mixture of water and another fluid having a boiling point less than water.
The volatile fluid is selected such that the graphs (pressure against temperature) of the volatile fluid and of water alone are nearly parallel and therefore, no matter w~at the steam pressure may be in the trap, at substantially any temperature t below the saturated steam temperature the volatile fluid begins to boil to cause the trap to shut~ ~`
It is to be noted in the trap of Figure 1 it is arranged that when the bellows 2 is fully expanded -trap fully open - the volatile fluid 15 completely fills the interior of the housing ~ outside the bellows 2. Thus in this condition the bellows 2 is fully supported and a surge in line pressure, due for example to waterhammer, is prevented from expanding the bellows further. The bellows cannot be overstretched and so cannot be damaged by waterhammer.
, 35 In the other extreme condition - trap fully closed bellows fully collapsed - it is arranged that the leaves of the bellows 2 are then very nearly touching. If super-, ~ Z~5~

heated steam is present, having the ef~ect of vapouris -ing the volatile fluid still further, the small amoun-t of movement necessary to permit the leaves of -the bellows fully to nest as a result of this further heating is taken up by the housing 6 lifting off the flange 8A against the action of the overload spring 9. Thus excessive pressure of the volatile fluid caused by overheating causes the bellows to adopt a fully nested condition and once this is reached the bellows can withstand great pressure without damage.
Figures 2A and 2B show balanced pressure thermostatic traps having thermostatic elementsthat are multi-diaphragm arrangements 2A (Figure 2A) or 2B (Figure 2B), the traps otherwise being the same æs the trap of Figure 1. Thus in each case there are two diaphragms 23, 24 sealed to one another at their peripheries so as to define an interior void 10 that is open to the casing 8. As in the case of the trap of Figure 1, the lower diaphragm 23 is fast with the bottom wall 7 of the housing 6 whilst the upper diaphragm 24 is free to move up and do~n and carries the valve member 13~ The interior of the housing 6, outside the diaphragm arrangement 2A or 2B; is filled with volatile ~luid 15 and each of these traps operates in the same way as the trap of Figure 1. `
In the Gase of Figure 2A each diaphragm 23,24 is of frusto-conical form in its relaxed condition. The diaphragms 23,24 of Figure 2B are of ~orrugated form.
As in the case of Figure 1, in the trap fu~-ly open condition the diaphragm arrangement 2A or 2B is fully supported by the volatile fluid which completely fills the interior of the housing outside -the diaphragm arrangement in this condition. In the trap fully closed condition the individual diaphragms are nearly touching, and fully nest if further heating occurs.

Claims (6)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A thermostatic steam trap comprising a base;
a cover mounted on the base, the base and cover defining a hollow interior of the trap; a casing within said interior fast with the base and cover; a housing movably mounted in the casing; resilient means urging the housing to seat in the casing; a balanced pressure thermostatic element mounted in the housing; a valve member carried by the thermostatic element; an inlet port to said interior;
an outlet port from said interior; and a valve seat in the outlet port; the casing locating the housing and the thermostatic element with respect to the outlet port so that the valve member carried by the thermostatic element co-operates with the valve seat in the outlet port for opening and closing the trap; the element defining an internal void that is open to steam/condensate within the trap and that is sealed from the interior of the housing in which the element is mounted; the housing having its interior sealed from said interior of the trap and containing volatile fluid which entirely fills the housing outside the element when the trap is fully open thereby to support the element; the element being moved by the pressure exerted by the volatile fluid upon heating of the fluid to urge the valve member carried by the element on to the valve seat to close the trap with the element, in the trap fully-closed condition, being in a nearly nesting condition; the housing moving away from its seating condition in the casing against the action of said resilient means; to permit the element to adopt a fully nesting condition if further heating of the volatile fluid occurs.
2. A steam trap as claimed in Claim 1, wherein the valve member is fast with an upper wall of the thermo-static element which wall moves up and down in the housing in dependence upon contraction or expansion of the volatile fluid in the housing; and wherein the internal void of the element is open to the steam/condensate through an aperture in the bottom wall of the housing through which aperture the valve member co-operates with its seat.
3. A steam trap as claimed in Claim 1, wherein the thermostatic element is a bellows.
4. A steam trap as claimed in Claim 1, wherein the thermostatic element is a multi-diaphragm arrangement.
5. A steam trap as claimed in Claim 3, wherein there are two opposed diaphragms each of frusto-conical form.
6. A steam trap as claimed in claim 3, wherein there are two opposed diaphragms each of corrugated form.
CA344,130A 1979-01-26 1980-01-22 Steam traps Expired CA1122500A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB7902777 1979-01-26
GB7902777A GB2041194B (en) 1979-01-26 1979-01-26 Steam traps
KR1019800000329A KR830001141B1 (en) 1979-01-26 1980-01-30 Thermal Steam Traps

Publications (1)

Publication Number Publication Date
CA1122500A true CA1122500A (en) 1982-04-27

Family

ID=26270345

Family Applications (1)

Application Number Title Priority Date Filing Date
CA344,130A Expired CA1122500A (en) 1979-01-26 1980-01-22 Steam traps

Country Status (11)

Country Link
KR (1) KR830001141B1 (en)
AR (1) AR220810A1 (en)
BE (1) BE881334A (en)
BR (1) BR8000493A (en)
CA (1) CA1122500A (en)
DE (1) DE3002378A1 (en)
ES (1) ES488043A1 (en)
FR (1) FR2447514A1 (en)
GB (1) GB2041194B (en)
IN (1) IN153624B (en)
IT (1) IT1130235B (en)

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE318381C (en) *
DE314150C (en) *
FR506990A (en) * 1919-04-16 1920-09-02 Emile Kuhn Improvements in automatic traps
US1646686A (en) * 1926-03-15 1927-10-25 William T Price Radiator return trap
US2628783A (en) * 1949-12-24 1953-02-17 Barnes & Jones Inc Control unit for thermostatic valves
GB922211A (en) * 1961-02-07 1963-03-27 Ici Ltd Improved steam traps
FR1482686A (en) * 1966-06-09 1967-05-26 Thermal bellows steam trap
US3876139A (en) * 1973-08-17 1975-04-08 Jr Peter N Schmidt Valve having integral filter

Also Published As

Publication number Publication date
FR2447514A1 (en) 1980-08-22
ES488043A1 (en) 1980-07-01
IT1130235B (en) 1986-06-11
IT8019497A0 (en) 1980-01-25
KR830001141B1 (en) 1983-06-14
BR8000493A (en) 1980-10-14
DE3002378A1 (en) 1980-08-07
DE3002378C2 (en) 1990-06-21
FR2447514B1 (en) 1984-12-21
BE881334A (en) 1980-05-16
GB2041194B (en) 1983-01-12
IN153624B (en) 1984-07-28
GB2041194A (en) 1980-09-03
AR220810A1 (en) 1980-11-28

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