Pilot-operated steam traps

Claim 2

A pilot operated steam trap having a body with an inlet and an outlet, means providing a control chamber carried by said body, main valve seat means provided between said inlet and said outlet, a main valve member mounted in said control chamber for displacement toward and away from said main seat to block and afford fluid flow from the inlet and to the outlet, a first flow passage providing fluid communication between said inlet and said control chamber to permit a quantity of control fluid to flow into said control chamber, second flow passage means providing fluid communication between said outlet and said control chamber to permit said control fluid to flow from said control chamber, a pilot valve cooperable with said second flow passage to afford and block flow of said control fluid therethrough, said pilot valve mounted for movement between a closed and a fully opened position, temperature responsive means in said control chamber to control the position of said pilot valve in response to the temperature in said control chamber, the capacity for total mass flow of said second flow passage when said pilot valve is in its fully opened position being greater than the capacity for total mass flow of said first flow passage so that the main valve member disengages its seat to afford flow through the trap after said pilot valve affords control fluid flow through the second flow passage and when said pilot valve closely approaches its fully opened position, means to provide a restriction to flow past said main valve in all open positions of said main valve to create a pressure drop across said main valve seat from the inlet to the outlet, and means at said second flow passage to provide a restriction to flow to create a pressure drop from said control chamber to said outlet in all open positions of the pilot valve means, the pressure drop from the control chamber to the outlet being substantially less than the pressure drop across said main valve to cause continuous flow of fluid through the control chamber to the outlet in all open positions of the main valve.

Claim 3

A pilot valve operated steam trap comprising spaced inlet and outlet chambers and a control chamber intermediate the inlet and outlet chambers, means defining a main valve seat between the inlet and outlet chambers, a main valve member positioned within said control chamber and adapted to seat on said main valve seat to prevent fluid communication between said inlet and said outlet chambers, said main valve member mounted for movement away from said valve seat to an open position, a pilot valve positioned between said inlet and outlet chambers operable to control fluid flow through said inlet and outlet chambers, said pilot valve mounted for movement between a closed and a fully openEd position, temperature responsive means positioned within said control chamber and connected to said pilot valve, said temperature responsive means operable to cause said pilot valve to move toward its open position when the temperature in said control chamber is less than a predetermined temperature and close when the temperature of said control chamber is greater than said predetermined temperature, said pilot valve operable to cause opening of said main valve member when the pilot valve closely approaches the full open position thereby allowing condensate to pass through said main valve and operable to cause closing of said main valve member when said pilot valve is moved toward and approaches said closed position to prevent passage of steam through said main valve, means to provide a restriction to flow past said main valve in all open positions of said main valve to create a pressure drop across said main valve seat from the inlet to the outlet, and means at said second flow passage to provide a restriction to flow to create a pressure drop from said control chamber to said outlet in all open positions of the pilot valve means, the pressure drop from the control chamber to the outlet being substantially less than the pressure drop across said main valve seat in all open positions of the pilot valve means and main valve to cause continuous flow of fluid through the control chamber to the outlet in all open positions of the main valve.

Claim 4

A pilot valve operated steam trap comprising spaced inlet and outlet chambers and a control chamber intermediate the inlet and outlet chambers, means defining a main valve seat between the inlet and outlet chambers, a main valve member positioned within said control chamber and adapted to seat on said main valve seat to prevent fluid communication between said inlet and said outlet chambers, said main valve member mounted for movement away from said valve seat to an open position, a pilot valve positioned between said inlet and outlet chambers operable to control fluid flow through said inlet and outlet chambers, said pilot valve mounted for movement between a closed and a fully openEd position, temperature responsive means positioned within said control chamber and connected to said pilot valve, said temperature responsive means operable to cause said pilot valve to move toward its open position when the temperature in said control chamber is less than a predetermined temperature and close when the temperature of said control chamber is greater than said predetermined temperature, said pilot valve operable to cause opening of said main valve member when the pilot valve closely approaches the full open position thereby allowing condensate to pass through said main valve and operable to cause closing of said main valve member when said pilot valve is moved toward and approaches said closed position to prevent passage of steam through said main valve, means to provide a restriction to flow past said main valve in all open positions of said main valve to create a pressure drop across said main valve seat from the inlet to the outlet, and means at said second flow passage to provide a restriction to flow to create a pressure drop from said control chamber to said outlet in all open positions of the pilot valve means, the pressure drop from the control chamber to the outlet being substantially less than the pressure drop across said main valve seat in all open positions of the pilot valve means and main valve to cause continuous flow of fluid through the control chamber to the outlet in all open positions of the main valve.

Claim 5

Apparatus according to claim 2 wherein the pilot valve is of a size to handle between approximately 10 to 25 percent of the total capacity of flow of fluid through the steam trap.

Claim 6

A pilot operated steam trap having a body with an inlet and an outlet, means providing a control chamber carried by said body, main valve seat means provided between said inlet and said outlet, means defining a main valve seat flow passage through said main valve seat providing fluid communication between said inlet and said outlet, said main valve seat flow passage having a restricted throat area therein, a main valve member mounted in said control chamber for displacement toward and away from said main seat to block and afford fluid flow from the inlet and to the outlet, the restricted throat area in said main valve seat flow passage operable to create a first pressure drop from said inlet to said outlet in all open positions of said main valve member, a first flow passage providing fluid communication between said inlet and said control chamber to permit a quantity of control fluid to flow into said control chamber, second flow passage means providing fluid communication between said outlet and said control chamber to permit said control fluid to flow from said control chamber, said second flow passage having a restricted throat area therein, a pilot valve moveable from a closed to a full open position cooperable with said second flow passage to afford and block flow of said control fluid therethrough, the restricted throad area in said second flow passage operable to create a second pressure drop from said control chamber to said outlet in all open positions of said pilot valve, said second pressure drop being substantially less than said first pressure drop in all open positions of said main valve member, temperature responsive means in said control chamber to control the position of said pilot valve in response to the temperature in said control chamber, the capacity for total mass flow of said second flow passage when said pilot valve is in its full open position being greater than the capacity for total mass flow of said first flow passage so that the main valve member disengages its seat to afford flow through said main valve after said pilot valve closely approaches its full open position.

Claim 7

A pilot operated steam trap having a body with an inlet and an outlet, means providing a control chamber carried by said body, main valve seat means provided between said inlet and said outlet, means defining a main valve seat flow passage through said main valve seat providing fluid communication between said inlet and said outlet, said main valve seat flow passage having a restricted throat area therein, a main valve member mounted in said control chamber for displacement toward and away from said main seat to block and afford fluid flow from the inlet and to the outlet, the restricted throat area in said main valve seat flow passage operable to create a first pressure drop from said inlet to said outlet in all open positions of said main valve member, a first flow passage providing fluid communication between said inlet and said control chamber to permit a quantity of control fluid to flow into said control chamber, second flow passage means providing fluid communication between said outlet and said control chamber to permit said control fluid to flow from said control chamber, said second flow passage having a restricted throat area therein, a pilot valve moveable from a closed to a full open position cooperable with said second flow passage to afford and block flow of said control fluid therethrough, the restricted throad area in said second flow passage operable to create a second pressure drop from said control chamber to said outlet in all open positions of said pilot valve, said second pressure drop being substantially less than said first pressure drop in all open positions of said main valve member, temperature responsive means in said control chamber to control the position of said pilot valve in response to the temperature in said control chamber, the capacity for total mass flow of said second flow passage when said pilot valve is in its full open position being greater than the capacity for total mass flow of said first flow passage so that the main valve member disengages its seat to afford flow through said main valve after said pilot valve closely approaches its full open position.

Claim 8

Apparatus according to claim 4 wherein said main valve seat flow passage comprises an elongated opening extending through said main valve seat, and said main valve member has an elongated tip thereon extending coaxially of and at least pArtially within said elongated passage, the tip on said main valve member providing an annular flow area surrounding said tip and in said main valve passage through which fluid may flow with said annular area forming in said main valve seat flow passage said restricted throat area.

Claim 9

Apparatus according to claim 5 in which said main valve seat flow passage is of generally circular cross-sectional shape and has an axial length approximately equal to its diameter.

Claim 10

Apparatus according to claim 6 in which when said main valve member is displaced away from said main valve seat the tip on said main valve member is inserted into said main valve seat flow passage a distance equal to at least approximately one-half of the diameter of said main valve seat flow passage.