Conduit arrangement with protection against rupture and leakage

• US 4,004,607 A
• Filed: 10/20/1975
• Issued: 01/25/1977
• Est. Priority Date: 10/28/1974
• Status: Expired due to Term

• Current Assignee: Svensk Konstruktionstjänst AB
• Original Assignee: Lennart Werner Freese
• Inventors: Freese, Lennart Werner
• Primary Examiner(s): Weakley, Harold W.
• Application Number:
  US05/623,712
• Time in Patent Office: 463 Days
• Field of Search: 137/460, 137/486, 137/498, 137/502
• US Class Current: 137/486
• CPC Class Codes: F16K 17/20 Excess-flow valves actuated in consequence of shock or similar extraneous influence F16K17/36
• CPC Class Codes: F16L 55/055 Valves therefor
• CPC Class Codes: Y10T 137/7727 Excessive flow cut-off
• CPC Class Codes: Y10T 137/7759 Responsive to change in rate of fluid flow
• CPC Class Codes: Y10T 137/7785 Valve closes in response to excessive flow
• CPC Class Codes: Y10T 137/7789 With Venturi tube having a connection to throat

Abstract

A conduit arrangement for heavy duty purposes in which a conduit section, such as a length of flexible hose, may be subjected in use to high stresses from pressures attaining several hundred atmospheres, wherein the arrangement provides protection against ruptures and significant leaks and comprises stop valve means at the inlet end of the conduit section, pressure drop type flow sensing means (e.g. an orifice plate or venturi restriction) at the outlet of said section, and pressure comparator means for comparing the pressure drop over the flow sensing means with that over the stop valve means and operative to effect a rapid closing operation of the stop valve means if the ratio of said pressure drops deviates by a certain amount from a predetermined value.

Claims

1. A valve means for protecting conduit systems against unintentional depressurization, occurring for example when ruptures or leaks arise in the system, the device being applied for monitoring especially exposed sections of the system, e.g. a flexible hose incorporated therein, and arranged automatically to stop or block the flow through such a section for an undesired change in pressure occurring therein, characterized in that a stop or blocking valve (20;

120) is mounted at the inlet of the monitored section (46), said valve normally being open and hereby offering the medium flowing through a modest resistance generating a certain pressure drop (Δ

p₁, FIG.

     3), while a flow sensing means (100) of the kind wherein a medium flowing through produces a pressure drop (Δ

p₂) in response to the size of the flow, and for example comprising an orifice plate or venturi constriction (105), known per se, is placed at the outlet of the section (46), the blocking valve (20;

     120) and the flow sensing means (100) communicating with a pressure comparator means (50;

     118) which is arranged to compare the pressure drops (Δ

p₁ and Δ

p₂, respectively) across the blocking valve and the flow sensing means, and operative to cause the blocking valve (20;

     120) to close the flow into the conduit section (46) if the ratio (Δ

p₂ /Δ

p₁) of the pressure drop over the flow sensing means (100) to that over the blocking valve (20;

     120) falls below a certain value (Δ

p₂ '"'"'/Δ

p₁).

2. A valve means as claimed in claim 1 in which the blocking valve (20) comprises a housing (16) with an inlet (14), a through passage with a valve seat (28) through which the medium flows, and an outlet (15), there being a movable valve body (18) arranged on the inlet side of the valve seat, the valve body being prevented by a latching means (30) from going into engagement with the seat and closing the valve under the action of the flowing medium, said latching means (30) comprising a movable latching piston (36) slidably accomodated in a cylindrical chamber (39) and arranged to engage the valve body (18) with an extended portion or tongue (34), the piston (36) on its upper side or the side accomodating the tongue (34) being arranged for actuation by the pressure prevailing on the inlet side of the blocking valve (20), while on its underside or side opposite to the tongue it is actuated by the pressure in its chamber (39) and by a spring or retaining means (38) arranged to actuate the piston (36) in a latching direction, characterized in that a conduit communication (64, 75, 74) is arranged from the chamber (39) on the inlet side of the latching piston (36) to the outlet side of the blocking valve, said conduit communication normally being broken by an auxiliary valve (52, 58) incorporated in the pressure comparator means (50) which is arranged, for closing the blocking valve (20), to cause the auxiliary valve (52, 58) to open the said conduit communication, thus causing the pressure in the latching piston chamber to fall to the lower pressure prevailing on the outlet side of the blocking valve, the piston thereby being displaced from its latching engagement with the valve body (18) under the actuation of the higher pressure on its upper side, thereby allowing the valve body to come into engagement with its seat (28).

3. A valve means as claimed in claim 2, characterized in that the pressure comparator means (50) also includes a movable piston slide (54), which on the one hand is exposed to the pressures prevailing on the inlet and outlet sides of the blocking valve (20) by means of the said conduit communication (62, 75, 74) in such a way that the difference (Δ

p₁) between these pressures strives to displace the piston slide (54) in one direction and, on the other hand, is exposed by a second conduit communication or pilot hose (80) to the pressures prevailing on the inlet and outlet side (104 and 106, respectively) of the flow sensing means (100) in such a way that the difference (Δ

p₂) between these pressures strives to displace the piston slide (54) in the opposite direction, whereby the slide is arranged to actuate its coacting auxiliary valve (52,

     58) to open the first-mentioned conduit communication (62, 75,

     74) if the said variation in the ratio (Δ

p₂ /Δ

p₁) of the pressure drops or pressure differences occurs.

4. A valve means as claimed in claim 2, characterized in that the auxiliary valve constitutes a valve ball (52) arranged to be brought into sealing engagement with a seat (58) by the piston slide (54).

5. A valve means as claimed in claim 1, in which the blocking valve (120) comprises a housing (115, 116) with an inlet (14, 122), a through passage (124, 126), and an outlet (130, 15), there being a slide means (118) arranged in the through passage of the valve, said slide means being movable between an open position in which the medium is allowed free flow through the valve, and a closing position in which flow of the medium through the valve is blocked, characterized in that the slide means (18) simultaneously constitutes the pressure comparator means in being arranged to be exposed, on the one hand, to the pressures prevailing at the inlet and outlet sides of the blocking valve (120) in such a way that the difference (Δ

p₁) between these pressures strives to displace the sliding means in one direction and, on the other hand, to the pressures prevailing on the inlet and outlet sides (104 and 106, respectively) of the flow sensing means (100) in such a way that the difference (Δ

p₂) between these two pressures strives to displace the slide means (118) in the opposite direction, the slide means being arranged to move to its closing position for blocking the flow through the valve if the said variation in the ratio (Δ

p₂ /Δ

p₁) of the pressure drops or pressure differences occurs.

6. A valve device as claimed in claim 5, characterized in that the slide means constitutes a cylindrical spool (118) which is slidably accomodated in a bore (133) in the valve housing (116) and is made with two end portions (117, 119) united by a reduced or waisted portion (132), arranged for being flowed past by the medium on its way from the inlet (14, 122) to the outlet (130, 15) of the valve housing (116) in such a way that the pressure drop (Δ

p₁) prevailing hereby across the net area of the spool at the waisted portion actuates the spool in said one direction, while the end portions (119,

     117) at the ends of the spool form the limits of chambers (152 and 134, respectively) in the bore (133), said chambers being in communication with the inlet side and outlet side, respectively, of the flow sensing means (100) in such a way that the pressure drop (Δ

p₂) occurring over said means actuates the spool in the opposite direction.

7. A valve means as claimed in claim 6, characterized in that the spool (118) is arranged to break the connection between the outlet side (106) of the flow sensing means and coacting chamber (134) in the bore (133) on initiation of its closing movement, to put said chamber (134) in direct communication with the inlet (122) of the blocking valve (120) instead.

8. A valve means as claimed in claim 7, characterized in that the said communication between the outlet side (106) of the flow sensing means (100) and the coacting chamber (134) comprises longitudinal and transverse ducts (136 and 140, respectively) in the spool (118), and also comprises a duct (132) arranged in the valve housing (115, 116), normally communicating with the transverse duct (140), which, however, is arranged to come into communication with another duct (138) in the housing upon said initiation of the spool closing movement, said last mentioned duct (138) leading directly to the inlet (122) of the blocking valve (120), thereby amplifying the pressure acting in the closing direction on the spool by the inlet pressure in the blocking valve.

9. A valve means as claimed in claim 1, characterized in that the pressure drop (Δ

p₂) over the flow sensing means (100) is transferred to the pressure comparator means (50;

     118) by the aid of a pilot hose (80) comprising double hoses, which communicate with each its side of the flow sensing means and of which the one (82) is arranged inside the other (84).