Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
  • F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
  • F16K17/02—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side
  • F16K17/04—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded
  • F16K17/10—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded with auxiliary valve for fluid operation of the main valve
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
  • F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
  • F16K17/02—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side
  • F16K17/04—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded
  • F16K17/10—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded with auxiliary valve for fluid operation of the main valve
  • F16K17/105—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded with auxiliary valve for fluid operation of the main valve using choking or throttling means to control the fluid operation of the main valve
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D90/00—Component parts, details or accessories for large containers
  • B65D90/22—Safety features
  • B65D90/32—Arrangements for preventing, or minimising the effect of, excessive or insufficient pressure
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T137/00—Fluid handling
  • Y10T137/7722—Line condition change responsive valves
  • Y10T137/7758—Pilot or servo controlled
  • Y10T137/7759—Responsive to change in rate of fluid flow
  • Y10T137/776—Control by pressures across flow line valve

Definitions

• the invention relates to a relief valve for relieving the pressure in a tank and comprising a valve seat and a valve body which are coherent with a primary membrane, whose one side is connected to the tank via a pilot passage and whose other side is connected on the one hand to the tank and, on the other, to a relief passage, and comprising a pilot valve unit with at least one pilot membrane configured for opening - by a set pressure - a pilot valve arranged in said pilot passage, said pilot passage having an inlet opening which is coupled to the tank, and an outlet opening.
• valves are used in particular for relieving the pressure in tanks, eg onboard a ship. Owing to variations in temperature it is important to be able to ventilate the tanks, but when the materials contained in the tank are combustible, particular severe requirements are made to the functioning of the valve and its ability to resist a fire.
• the tank contains a liquid that emits combustible gases to the effect that the mixture contained in the tank is combustible. This makes requirements both to the relief valve preventing blow-backs of flames from the outside and simultaneously operating with such small differences in pressure for opening and closing that the evaporation from the tank is reduced to a minimum.
• Pilot membranes of the kind mentioned above are well known and associated with the advantage that they are able to open very quickly if merely the pressure in the tank is slightly higher than the set pressure. In turn, they are not fire-retardant; rather they are dangerous because of said outlet opening being ventilated to the open. This means that eg a deck fire is able to transplant sideways through the pilot valve to the tank. It is the object of the invention to provide a relief valve, wherein an improvement of the opening/closing functions is accomplished simultaneously with it providing safety that a fire cannot transplant sideways through the valve.
• the prior art would be associated with the risk of blow-back of flames when the pressure and hence the flow rate in the relief passage have dropped.
• this is avoided by means of the excess-pressure valve which will close before the flames reach anywhere near the relief passage.
• the outlet opening being connected to the relief passage and the latter being blocked off relative to the surroundings by means of the excess-pressure valve, there is no longer any risk either that a fire may propagate through the pilot valve.
• sub-atmospheric pressure it will prevail at both sides of the primary membrane which will be able to open to the effect that passage is enabled from the tank to the relief passage.
• the relief passage comprises an excess-pressure valve, it will close and prevent back-suction which would be disastrous in case of a deck fire.
• the excess-pressure valve comprises a torpedo-shaped valve body with an essentially vertical axis. It serves to gather the out-flowing gases to a concentrated jet which can be thrown upwards when, in the in-use position, the relief passage faces upwards.
• the excess-pressure valve can merely be biased by means of a spring and/or the own weight of the valve body, but in accordance with a preferred embodiment a magnet is also provided, whose magnetic force serves to make the opening pressure higher than the closing pressure. This will contribute to allowing the excess-pressure valve to open slightly later, whereby further improvements of the opening cycle of the valve can be obtained as described above, simultaneously with the valve closing at a relatively lower pressure.
• Figure 1 is a sectional view through an embodiment
• Figure 2 is an enlarged sectional view of the embodiment shown in Figure 1.
• the valve shown in Figure 1 has a flange 12 for attachment of the valve on or in connection with a tank.
• the tank is a loading tank in a ship, eg for transporting liquids giving off combustible vapours.
• severe requirements are made to safety in respect of a relief valve which is to be able to both ventilate the tank in case of super-atmospheric pressure and which is to allow air to enter in case of sub-atmospheric pressure.
• combustible gases they may be ignited eg by strike of lightning, and in case of vacuum in the tank a deck fire will be able to readily transplant to the combustible gases in the tank.
• the relief valve acts such that it does not allow more gas to escape than absolutely necessary. If the pressure in the tank becomes unnecessarily low, it will further evaporation of the liquid in the tank. In practice, large amounts of liquid may evaporate in this manner during transport by ship. Therefore, a relief valve to this end should be able to operate within a very small difference in set pressure and closing pressure. In practice the flange 12 is not secured to the tank, but connected thereto via pipe system of a certain length which means that a pressure drop will occur as soon as gas flows through the pipe.
• the valve comprises a chamber 13 which is connected to a tank via the flange 12 and is in connection with a vacuum valve 14 which is known per se and which serves the purpose of being activated in case a vacuum occurs in the chamber 13.
• a vacuum valve 14 also comprises means that are known per se for preventing flames in the surroundings from propagating into the chamber 13.
• the chamber 13 is connected to a relief valve 5 via a valve that comprises a valve seat 1 and a valve body 2.
• the valve body 2 is carried by a primary membrane 3 and is journalled such that the valve opens when the membrane is influenced to move upwards. In such case the super- atmospheric pressure from the tank will be able to propagate to the relief passage 5 and from there to the open via an excess-pressure valve 11 as will be described later on.
• valve part 6 shown in Figure 2 functions.
• that part will be designated the 'pilot valve unit 6' which is connected to the chamber 13 via an inlet opening 9 and is connected to the relief valve 5 via an outlet opening 10 and is finally connected to a chamber 15 which is, in the shown embodiment, delimited downwards by the primary membrane 3.
• the pilot valve unit 6 comprises a control membrane 16 and a pilot membrane 7, wherein the top face of the pilot membrane 16 is in connection with the open, while the space between the membranes 7 and 16 is connected to the inlet opening 9 via a throttle means 17.
• the bottom face of the membrane 7 is also connected to the inlet opening 9, but around the throttle means 17.
• the valve also comprises a pilot passage 4 which is connected to the pilot chamber 15, to the inlet opening 9 via the throttle means and which is usually upwardly open by means of a pilot valve 8. If the membranes 16 and 7 are moved upwards, the pilot valve 8 will open to the effect that gas is able to flow from the inlet opening 9 to the outlet opening 10.
• the pilot valve unit 6 comprises a spring 24 which is adjustable and presses the membrane 16 downwards by a predetermined and adjustable force.
• the membranes are connected to each other via the valve body of the valve 8, which parts are journalled for vertical movement under the influence of the pressure from the spring 24 and the gas pressures on the membranes.
• the chamber 15 will also be evacuated and very quickly cause the membrane 3 to lift the valve body 2 upwards. This is due not only to the chamber 15 being evacuated, but also to the pressure in the relief passage 5 increasing as a consequence of the outlet opening 10 being, in accordance with the invention, connected to the relief passage 5.
• the described booster- effect accomplished by means of the membranes 16 and 7 are known per se, but one of the advantages of the present invention is that the flow of gas that travels through the pilot valve and which is a prerequisite for the known booster effect, flows into the relief passage 5 and thereby provides a hitherto unknown increased booster effect.
• the super-atmospheric pressure 11 will be described in further detail. Exteriorly it has the shape of a torpedo-shaped body which has the known effect that the out-flowing gas is gathered to a concentrated jet which is thrown high into the air.
• the bottom of the torpedo-shaped body is configured as a valve body 18 which is configured to abut on a valve seat 19.
• a guide 20 is provided which is vertically movable within a spindle guide 21 which is, by means of not shown means, fixated in relation to the valve seat 19.
• a magnetic disc 22 is provided which is configured to cooperate with another magnetic disc or a disc of a magnetisable material 23 wherein the latter disc is adjustable in height to the effect that the magnetic attraction force between the discs 22 and 23 can be adjusted to a predetermined value when the valve body 18 abuts on the valve seat 19. It is thus the magnetic force that keeps the valve body 18 down towards the valve seat 19.
• the excess-pressure valve 11 will open whereby the disc 23 is caused to be situated at a larger distance from the disc 22 to the effect that the magnetic attraction force decreases and such that the valve 11 is almost instantaneously moved to its top position which allows the largest possible flow.
• the magnetic discs 22 and 23 also have the effect that the closing pressure is slightly lower than the opening pressure. However, it is not lower than the flow rate measured at the valve seat 19 always exceeding the propagation rate of flames, if any, to the effect that blow-back of flames will cannot occur in a direction down into the relief passage 5.
• the excess-pressure valve 11 could also be a purely spring-controlled and/or mass controlled valve, whose opening and closing pressures are essentially the same. This could mean that the excess-pressure valve 11 closes immediately before the pilot valve unit 6 closes. However, when the excess- pressure valve 11 is closed there is no risk of flame blow-back through the relief passage 5 and via the still open valve down to the chamber 13 and the tank.
• a combination of a magnetically controlled valve, a spring-controlled and a mass-controlled valve will give the designer a wide degree of freedom to ensure that the excess-pressure valve 11 functions optimally in the context of the pressure and flow conditions that occur in the relief chamber 5 which are, in turn, controlled by the set pressure and the closing pressure of the pilot valve.
• the relief passage 5 being closed towards the open by means of an excess- pressure valve and by the outlet opening 10 being connected to the relief passage 5, a valve is accomplished which, compared to the prior art, is both more fire-retardant and operationally more reliable.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Safety Valves (AREA)
• Lubrication Of Internal Combustion Engines (AREA)
• Fluid-Driven Valves (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Publications (1)

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Citations (4)

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• 2006
  • 2006-09-15 DK DK200601193A patent/DK176684B1/da not_active IP Right Cessation
• 2007
  • 2007-09-12 EP EP20070801374 patent/EP2071220B1/en not_active Not-in-force
  • 2007-09-12 AT AT07801374T patent/ATE479860T1/de not_active IP Right Cessation
  • 2007-09-12 CN CN2007800382771A patent/CN101611252B/zh not_active Expired - Fee Related
  • 2007-09-12 JP JP2009527699A patent/JP5306209B2/ja not_active Expired - Fee Related
  • 2007-09-12 DE DE200760008923 patent/DE602007008923D1/de active Active
  • 2007-09-12 WO PCT/DK2007/000406 patent/WO2008031435A1/en not_active Ceased
  • 2007-09-12 KR KR1020097007747A patent/KR101221998B1/ko not_active Expired - Fee Related
  • 2007-12-09 US US12/310,850 patent/US20100024901A1/en not_active Abandoned
• 2009
  • 2009-04-15 NO NO20091466A patent/NO20091466L/no unknown

Patent Citations (4)

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