US3627384A

US3627384A - Safety relief valve structure for railway cars

Info

Publication number: US3627384A
Authority: US
Inventors: Dallas W Rollins; Richard H Dugge
Original assignee: ACF Industries Inc
Current assignee: ACF Industries Inc
Priority date: 1969-09-11
Filing date: 1969-09-11
Publication date: 1971-12-14
Anticipated expiration: 1988-12-14

Abstract

A safety relief valve structure for a railway car having an enclosed shell which is adapted to be placed under an internal fluid pressure, especially for unloading particulate lading. A pilot-operated safety valve on the car has a main valve inlet communicating directly with the interior of the car, and a separate pilot line provides fluid communication between the interior of the car and the safety relief valve for controlling the operation of the valve. A filter is positioned in the separate pilot line and minimizes any passage of air entrained lading to the safety valve through the pilot line. The filter comprises a housing and a filter element within the housing through which the air and any entrained lading particles pass. The filter element has a micron rating between around five and 25 to entrap lading particles of a micron size greater than the micron rating of the filter element.

Description

United States Patent [72] Inventors Dallas W. Rollins St. Charles; Richard II. Dugge, St. Louis, both of Mo. [21] Appl. No. 857,098 [22] Filed Sept. 11, 1969 [45] Patented Dec. 14, 1971 [73] Assignee ACF Industries, Incorporated New York, N.Y.

[54] SAFETY RELIEF VALVE STRUCTURE FOR RAILWAY CARS 1 Claim, 4 Drawing Figs.

[52] US. Cl 302/53, 302/52, 137/489 [51 Int. Cl B65g 53/40 [50] Field of Search 302/53, 52; 137/489; 251/44 [56] References Cited UNITED STATES PATENTS 1,228,104 5/1917 Fulton 137/489 1,719,686 7/1929 Browne 137/489 3,438,682 4/1969 Mohrhusen 302/52 3,469,888 9/1969 Aller et al. 302/52 Primary Examiner-Harvey C. Hornsby Assistant ExaminerMerle F. Maffei AllomeyEugene N. Riddle lading. A pilot-operated safety valve on the car has a main valve inlet communicating directly with the interior of the car, and a separate pilot line provides fluid communication between the interior of the car and the safety relief valve for controlling the operation of the valve. A filter is positioned in the separate pilot line and minimizes any passage of air entrained lading to the safety valve through the pilot line. The filter comprises a housing and a filter element within the housing through which the air and any entrained lading particles pass. The filter element has a micron rating between around five and 25 to entrap lading particles of a micron size greater than the micron rating of the filter element.

PATENTED HEB] 41s" SHEET 1 [IF 2 INVENTORS.

DALLAS W. ROLLINS RICHARD H. DUGGE ATTORNEY SAFETY RELIEF VALVE STRUCTURE FOR RAILWAY CARS BACKGROUND OF THE INVENTION Conventional safety valves for covered hopper railway cars, especially when employed with particulate lading, such as cement or flour, are subject to clogging of the working parts of the valve from lading contamination and wear on the valve seat upon the blowing of the lading from the valve during operation of the safety relief valve. Thus, especially after prolonged use with a railway covered hopper car in which particulate lading is being carried and unloaded by pressurizing the interior of the car, valve members are not apt to seat properly in many instances and the working parts may not function adequately in many instances because of lading contamination.

DESCRIPTION OF THE INVENTION The present invention is directed to a safety relief valve structure for a railway car having an enclosed shell which is subjected to internal fluid pressure, especially for unloading particulate lading, such as cement or the like. A pilot-operated safety relief valve is provided which has the pilot portion and all working parts of the valve completely sealed from the valve main inlet to the interior of the car. The safety valve has a fluid control chamber formed between a main diaphragm across the main inlet and a control diaphragm in a spaced generally parallel relation to the main diaphragm. A small pilot line which senses the pressure of the car is in fluid communication with the fluid control chamber to provide a pressure therein corresponding to that of the interior of the car. To prevent the pilot line from permitting the passage of particulate particles into the safety relief valve, a filter is placed within the pilot air line and comprises a filter element having a micron rating of between around 5 and 25 microns with a filtration area of 50 to I square inches. Such a filter element ensures that only lading particles smaller than that of the micron rating of the filter will pass into the valve. Micron ratings below or microns which may pass through the valve should not affect the operation of the valve or result in particles clogging the valve. By utilizing a separate pilot line and a separate control diaphragm, a very effective reseating of the main diaphragm is provided. The valve may be set to be actuated upon an internal pressure of 6 p.s.i., for example, being reached within the interior of the car, and will reseat itself when the pressure within the car is lowered to around 5% or 5% p.s.i. The main diaphragm valve has a minimum of chatter and has a seat which will not deteriorate from the friction of lading or valve chatter.

The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

ln the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

FIG. 1 is a section of a covered hopper railway car having a safety relief valve structure comprising the present invention positioned on the roof thereof and communicating with the interior of the car;

FIG. 2 is an enlarged partial top plan of the roof showing the valve structure thereon;

FIG. 3 is a sectional view of the specific safety relief valve employed in the safety valve structure of the present invention; and

FIG. 4 is a section of the filter means positioned in the pilot line of the safety valve structure comprising the present invention.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring now to the drawings for a better understanding of this invention, a covered hopper railway car is generally indicated l0 and has sides 12 connected by a roof I4. Hopper 10 has a bottom discharge outlet 16 for the pneumatic discharge of lading, such as flour or cement, from the car at an unloading site. Normally, railway car 10 is not pressurized in transit but is pressurized at the unloading site for unloading pneumatically the material in a suitable storage structure or highway vehicle adjacent the track. For unloading, a source of air is connected to the car and the car is pressurized to an internal fluid pressure of around 5 p.s.i., for example. Then, a suitable unloading hose is connected to the outlet and the lading is drawn from the interior of the car. For further details of the unloading system, reference is made to US. Pat. No. 3,302,979 dated Feb. 7, 1967, the entire disclosure of which is incorporated by this reference.

The safety valve structure comprising the present invention is generally indicated 30 and is positioned on the upper portion of roof 14. An inlet pipe 32 has its lower end within the interior of car 10 and has its upper end connected directly to a safety relief valve generally indicated 34. A pilot bypass line 36 has an inlet 38 adjacent one end thereof communicating with the interior of the car and has its other end connected to safety valve 34 at 40.

Mounted within bypass line 36 and comprising an important part of this invention is a filter structure generally indicated 42. Filter structure 42 comprises a base 43 having an inlet 44 and an outlet 46. A removable housing 48 is threaded onto base 52 to permit a filter element or cartridge 54 to be removably positioned therein. Filter element 54 is generally cylindrical in shape and has a central bore 56 therethrough. Air and entrained lading enter inlet 44 from bypass line 36. The air flows through filter element 54 into the central bore 56 thereof and out through outlet 46 leaving any lading or foreign matter embedded with filter element 54. Thus, filter element 54 removes lading from the air which enters the pilot line. Filter element 54 may preferably have a micron rating of between around 5 and 25 with a filtration area of between around 50 and mo square inches. Thus, particles down to 5 or 10 microns in size will be entrapped in filter element 54. Lading particles smaller than 5 or 10 microns will pass through the filter structure 42 and will not affect the operation of safety valve 34 due to their small particle size. A relatively large filtration area is required to provide adequate life for the filter and to reduce the pressure drop of the fluid pressure moving through bypass line 36 to valve 34. If the pressure drop is too great, the sensitivity of valve 34 will be affected and might not reseat as fast as desirable. The filter element or cartridge may be of cotton, Dynel, polypropylene, Orlon, nylon, or glass fibers with a micron rating of between 5 and 25.

Safety relief valve 34 comprises a base 60 having inlet 32 threaded thereon and communicating with the interior of car 10. Valve seat 62 has a main diaphragm 64 seated thereon. Diaphragm 64 is normally urged into seated engagement on seat 62 by spring 66. Spring 66 is compressed between spring seat 68 carried by diaphragm 64 and a stud 70 on valve cover 71. Upon unseating of main diaphragm 64, vents 72 in base 60 permit the air and entrained lading to be vented to atmosphere.

A fluid control chamber 73 is provided between main diaphragm 64 and a pilot-controlled diaphragm 74. Control diaphragm 74 is clamped between valve cover 71 and a spring housing 76 by studs 78. A control spring 80 is biased between a lower valve seat 82 on control diaphragm 74 and an upper valve seat formed by an adjusting screw 84. Screw 84 may be manually adjusted to control the bias of spring 80. A lock nut 86 secures adjusting screw 84 in position. Air from bypass line 36 enters port 88 which is in fluid communication with control chamber 73 through port 90. Thus, fluid control chamber 73 is in fluid communication with the interior of car 10.

A lever 92 is pivoted at 94 to spring housing 76 and has one end 96 fitting on the upper end of spring seat 82. The upper end of a pilot valve 100 is contacted by the other end 98 of lever 92 at 102. A spring retainer 104 houses a pilot valve spring 106 and upon a downward movement of lever end 98, valve 100 is unseated to relieve the pressure within the fluid control chamber 73.

ln operation, upon an internal pressure within the interior of car 10 being reached which exceeds 6 p.s.i., for example, main diaphragm 64 will be unseated to permit air and entrained lading to be vented or blown to atmosphere through vent ports 72. The pressure within fluid control chamber 73 is responsive to the internal pressure of car 10 through bypass valve line 36, filter 42, port 88, and port 90. Valve 100 is unseated likewise at a pressure of 6 psi. to vent chamber 73 to atmosphere. Upon a reduction in the internal pressure of car 10 to around p.s.i., for example, valve 100 will seat thereby effecting a buildup of pressure within chamber 73 which will likewise effeet a prompt seating of main diaphragm 64 on seat 62. Thus, a sensitive control for efiecting a prompt seating of diaphragm 64 upon a reduction in pressure within car is provided. A suitable valve 34 may be purchased commercially from the Micromat Company, Hillsdale, NJ.

Filter 42 effectively filters the bypass air from the interior of car 10 and prevents any large particles from entering the working mechanism of valve 34 thereby minimizing any clogging or malfunctioning of valve 34 from lading or foreign matter in any of the working parts of valve 34. Filter 42 has been found to be highly effective and permits valve 34 to func tion efl'ectively under prolonged conditions of service.

What is claimed is:

1. In a fluid pressure relief structure for a covered hopper railway car adapted to be placed under internal fluid pressure for unloading finely divided lading particles, said fluid pressure relief structure comprising; a safety valve having a' main valve inlet communicating with the interior of the car, a separate pilot line connected to said safety valve and in fluid connection with the interior of the car, said safety valve comprising a pair of spaced generally parallel diaphragms and a fluid control chamber between the diaphragms, the pilot line being in communication with the fluid control chamber, one of said diaphragms being a main diaphragm normally seated across the main valve inlet and exposed directly to the interior of the car, a vent to atmosphere to relieve the pressure within the car upon unseating of the main diaphragm upon an excessive pressure within the car, and an additional vent to atmosphere responsive to the other of said diaphragms to relieve the fluid pressure within the fluid control chamber from the pilot line for effecting a prompt reseating of said main diaphragm after the excessive pressure within the car has been vented to atmosphere by the first-mentioned vent; and filter means in said separate pilot line to minimize the passage of any finely divided lading particles to the safety valve through the pilot line, said filter means comprising a housing with an inlet and outlet connected to the pilot line, a filter element within the housing through which the fluid in the pilot line passes, said filter element having a micron rating between around 5 and 25 and entrapping lading particles having a micron size greater than the rating of the filter element.

i 4 i I!

Claims

1. In a fluid pressure relief structure for a covered hopper railway car adapted to be placed under internal fluid pressure for unloading finely divided lading particles, said fluid pressure relief structure comprising; a safety valve having a main valve inlet communicating with the interior of the car, a separate pilot line connected to said safety valve and in fluid connection with the interior of the car, said safety valve comprising a pair of spaced generally parallel diaphragms and a fluid control chamber between the diaphragms, the pilot line being in communication with the fluid control chamber, one of said diaphragms being a main diaphragm normally seated across the main valve inlet and exposed directly to the interior of the car, a vent to atmosphere to relieve the pressure within The car upon unseating of the main diaphragm upon an excessive pressure within the car, and an additional vent to atmosphere responsive to the other of said diaphragms to relieve the fluid pressure within the fluid control chamber from the pilot line for effecting a prompt reseating of said main diaphragm after the excessive pressure within the car has been vented to atmosphere by the firstmentioned vent; and filter means in said separate pilot line to minimize the passage of any finely divided lading particles to the safety valve through the pilot line, said filter means comprising a housing with an inlet and outlet connected to the pilot line, a filter element within the housing through which the fluid in the pilot line passes, said filter element having a micron rating between around 5 and 25 and entrapping lading particles having a micron size greater than the rating of the filter element.