GB2060829A

GB2060829A - Safety valve

Info

Publication number: GB2060829A
Application number: GB8028725A
Authority: GB
Original assignee: Gustav F Gerdts KG
Current assignee: Gustav F Gerdts KG
Priority date: 1979-10-11
Filing date: 1980-09-05
Publication date: 1981-05-07
Also published as: FR2467343B1; IT1128598B; DE2941173C2; FR2467343A1; SE8007063L; DE2941173B1; ES8105840A1; ES495053A0; IT8049865A0; GB2060829B

Abstract

A closure member (5) for a valve seat (4) has a spindle (6) which with a closer spring (7) and a flow pipe (8) extend into a vessel (1) from a housing (3) which has a lateral opening (11) in which a rupture member (12) is secured. In the event of excessive pressure in the space (10), the disc (12) will rupture and the valve member (5) can be forced off its seat (4) by the pressure in the space (10). <IMAGE>

Description

SPECIFICATION Safety valve This invention relates to a safety valve for pressure vessels having a housing with a valve seating adapted to be secured at the top on the vessel wall, a closure member cooperating with the valve seating and having a valve spindle protruding into the vessel and a closer spring arranged to act on the valve spindle.

Such valves, as described in German Gebrauchsmuster No. 7044704, require only relatively little head room above the pressure vessel. This has the great advantage that the maximum possible vessel overall height can be realised within the permissible overall head room which is limited for mobile pressure vessels such as tank trucks and tank containers. Furthermore such valves offer extremely great security against breaking away of the valve in the case of an accident. Due to the fact that the closer spring is arranged in the interior of the vessel it is protected against burning out and seizing in the case of the action of fire upon the pressure vessel.

For extremely dangerous media, for example toxic or highly corrosive liquefied gases and liquids, regulations exist to the effect that the safety valve must be preceded by a rupture member, for example a safety disc, which closes the valve passage. At the same time the entry opening of the safety valve should be situated in the gas space of the pressure vessel.

The valve spindle and the closer spring in the above-mentioned valve type opposed the corresponding arrangement of a rupture member.

The present invention aims to provide a safety valve of the above-mentioned type which offers the possibility of providing a rupture member in a simple manner within the gas space of the vessel.

According to the invention, there is provided a safety valve for pressure vessels having a housing with a valve seat adapted to be secured at the top on the vessel wall, a closure member co-operating with the valve seating and having a valve spindle protruding into the vessel, and a closer spring which acts at one end on the valve spindle and bears with its other end on an abutment on the housing, wherein the housing is provided with a flow pipe protruding into the vessel and having a lateral entry opening above the permissible liquid level, the flow pipe being provided at the entry opening with securing means for a rupture member for closing the entry opening.

The flow pipe with the lateral entry opening permits the entry opening to be arranged above the filling liquid in the immediate vicinity of the upper vessel wall, despite the usually relatively long closer spring and valve spindle protruding down into the filling liquid of the pressure vessel. The flow pipe also makes it possible to arrange the rupture member before the entry opening without problems.

Preferably, the flow pipe has a bottom beneath the lateral entry opening through which extends the valve spindle, the end face of said bottom remote from the vessel wall, or a part connected therewith, forming said abutment for the closer spring. With this arrangement, the closer spring is situated entirely outside the outflow path in the safety valve and does not hinder the blow-off current.

The closer spring is desirably screened off from the filling liquid of the pressure vessel and its possibly harmful attack by means of a hood which is located over the valve spindle and the closer spring may be secured to the bottom of the flow pipe.

According to a preferred embodiment of the invention, a guide pipe for the valve spindle is mounted in the bottom of the flow pipe, said guide pipe extending upwards in the flow pipe. This arrangement ensures precise guidance of the stroke of the closure part.

The invention will now be further described, by way of example, with reference to the drawing which shows a vertical section through one embodiment of a safety valve according to the invention.

Referring to the drawing, the upper vessel wall 1 of a pressure vessel, of which only a fragment is illustrated, comprises an attachment opening 2 for the safety valve. The valve housing 3 has a valve seat 4 with which a closure member 5 co-operates which comprises a valve spindle 6 and is subject to the action of a closer spring 7. The housing 3 is also provided with a flow pipe 8 which extends through the attachment bore 2 into the pressure vessel. Above the filling liquid 9, in the gas space 10 of the pressure vessel, the flow pipe 8 has a lateral entry opening 11 which is closed by a rupture member formed as a safety disc 1 2. Securing means 1 3 hold the safety disc 1 2 on the flow pipe 8.

The bottom 1 4 of the flow pipe 8 is penetrated by a guide tube 1 5 secured thereto which extends up centrally in the flow pipe 8.

The valve spindle 6 of the closure member 5 is guided for reciprocating movement in the guide tube 1 5. At its free lower end it carries an abutment 1 6 for one end of the closer spring 7 which concentrically surrounds the valve spindle 6. This spring bears with its other end against the end face 1 7 of the bottom 1 4 remote from the vessel wall 1, on which bottom 1 4 there is further held in sealing manner a hood 1 8 fitted over the valve spindle 6 and the closer spring 7 from beneath.

Since the closer spring 7 is situated beneath the liquid surface level 1 9 it is pro tected against burning out and seizing in the case of action of fire upon the pressure vessel.

At the same time however it is screened off by the hood 1 8 against direct action by the filling liquid 9. The closer spring 7 and the valve spindle 6 are thus not exposed to the filling liquid 9.

Although the safety valve extends down into the filling liquid 9, as a result of the provision of the flow pipe 8 and the radial orientation of the entry opening 11 in relation to the valve spindle 6, the entry opening is still situated above the maximum permissible liquid level 19, that is in the gas space 10.

If the internal pressure of the vessel exceeds its permissible maximum value, for example as a result of the action of fire upon the pressure vessel, then the safety disc 1 2 bursts. The excess vessel internal pressure establishing itself thereupon in the flow pipe 8 as well, lifts the closure part 5 away from its valve seat 4 against the action of the closer spring 7. Liquid vapour or gas can escape to atmosphere from the gas space 10 until the internal pressure of the vessel has dropped again to the permissible value and the safety valve closes again.

Claims

1. A safety valve for pressure vessels having a housing with a valve seat adapted to be secured at the top on the vessel wall, a closure member co-operating with the valve seating and having a valve spindle protruding into the vessel, and a closer spring which acts at one end on the valve spindle and bears with its other end on an abutment on the housing, wherein the housing is provided with a flow pipe protruding into the vessel and having a lateral entry opening above the permissible liquid level, the flow pipe being provided at the entry opening with securing means for a rupture member for closing the entry opening.

2. A safety valve according to claim 1, wherein the flow pipe has a bottom beneath the lateral entry opening through which extends the valve spindle, the end face of said bottom remote from the vessel wall, or a part connected therewith, forming said abutment for the closer spring.

3. A safety valve according to claim 2, wherein a hood is located over the valve spindle and the closer spring and is secured to the said bottom of the flow pipe.

4. A safety valve according to claim 2 or claim 3, wherein a guide pipe for the valve spindle is mounted in the bottom of the flow pipe, said guide pipe extending upwards in the flow pipe.

5. A safety valve substantially as described herein with reference to the drawing.