GB2062174A - Float-actuated device for venting closed vessels - Google Patents

Abstract

A flexible walled tube 22 typically of neoprene rubber, is attached to the lower end of a rigid tube 20, 24 and the upper end of the flexible walled tube is maintained at an elevated position within the vessel by securing it at 30 to the rigid fixed tube 20. The latter vents to the outside through a standard fitting and a spherical shell 26 secured to the tube 22 lifts the latter and kinks the tube with a rising liquid level 28 within the vessel. As soon as the tube is kinked, the passage to the outside through the fixed tube 20 is shut off. <IMAGE>

Description

SPECIFICATION Improvements in and relating to fluid vents Field of Invention This invention concerns vents for fluids such as gases vapours and liquids.

Background to the Invention It is often necessary to vent gases and vapours and sometimes liquids from vessels which may themselves contain inter alia liquid and gases.

Conventionally float operated valves have been used to open and close the vent passage. Such devices have operated on the principle of a floating member which falling in sympathy with a falling fluid level will cause a valve closure member to be moved away from it's seating thus opening a fluid passage from the interior of the vessel. Direct acting float valves (i.e. without hinges), have to employ some method of locating the valve closure member in such a way that it can fully cover the valve seat when it is intended that the valve be shut. This implies some form of fixed guide which will be in contact with the moving parts, albeit likely so as to provide the desired locating function.

In operation such prior art valves have a tendancy to become clogged with particulate matter particularly where the fluid in the vessel constitutes a suspension of particulate material in water or some other liquid. Clogging that can occur whether the particulate material is carried into the vessel in suspension or whether it is precipitated from solution in the vessel.

If the vessel contains media such as is to be found in filters or ion exchange systems, particles of such media may also be deposited on the moving parts of the closure valve referred to above. The particles may also deposit or become embedded into the valve closure member or into it's seating so that a good seal is not obtained between the mating surfaces. This prevents complete closure and possible loss of excess fluid.

It is an object of the present invention to provide a valve which includes no relatively moving parts which can become clogged by precipitated or suspended particulate material in the liquid.

The Invention According to the present invention a fluid vent for a vessel comprises a fixed outlet in the vessel at a high level, rigid fluid passage means communicating between the outlet and a lower point within the vessel, a flexible walled tube joined to the rigid fluid passage means at or near the said lower point and forming a 'U' bend with the remote end of the flexible walled tube secured at an elevated position within the vessel, and float means attached to or acting on the flexible walled tube forming the 'U' bend, the position of the float being selected so that as the fluid level within the vessel rises, the float will also rise and cause the flexible walled tube to become kinked and to shut off the fluid passage through the outlet from the inside of tbD vessel.

A preferred material for the flexible walled tube is neoprene rubber. This material is suitable for use with fluid at temperatures in the range 0--2 5 0 C.

It is of course, a pre-requisite that any material used for the flexible walled tube shall have no adverse reaction such as a chemical reaction with the fluid or any particulate material present in the fluid, in the vessel.

Since it is a further pre-requisite of the flexible walled tube that on becoming kinked the tube will flatten and close, the relative dimensions of the diameter of the tube and the wall thickness must be such that upon being kinked the tube will flatten and close. It has been found that for neoprene rubber tubing, the latter should be a nominal 3 mm bore and 0.5 mm wall thickness.

Conveniently the float means comprises a hollow spherical member having a specific gravity considerably less than the specific gravity of the fluid so that the member will float thereon and will provide sufficient buoyancy to raise the flexible walled tube against it's own weight and produce the required kinking.

Conveniently the float means is attached to the flexible walled tube by means of an adhesive.

Where the tube is of neoprene rubber, an anaerobic adhesive is preferably used.

In order to maintain the open end of the flexible walled tube in an elevated position within the vessel, the latter may to advantage be stuck to the inside wall of the vessel or to the rigid passage means previously referred to.

Typically the rigid passage comprises a length of rigid tubing for example plastics tubing which extends from a standard fitting which can be secured into an appropriately threaded aperture in an upper region of the vessel and the flexible walled tubing is secured to the lower end of the rigid tube.

The invention is a particular application in vessels used to contain water treatment materials for removing iron in solution or suspension in water supplies.

The invention will now be described by way of example with reference to the accompanying drawing.

In the Drawing Fig. 1 is a cross section through a water treatment vessel containing a fluid vent constructed in accordance with the invention.

Fig. 2 is an enlarged cross section through the lower end of the vent tube shown in Fig. 1.

Detailed Description of Drawings Referring to Fig. 1, a water treatment vessel 10 includes a liquid/gas inlet 12 and a liquid outlet 14. The vessel is intended to remove iron in solution or suspension from water entering at the inlet 12 and to this end a plurality of spherical objects and related media are located in the lower part of the vessel as designated by reference numeral 1 6. Reference is made to my copending Patent Application 43455/77 for a description of a water treatment process for removing iron in solution or suspension in water supplies.

As the level of liquid within the vessl rises, the air above the water is expelled through an outlet 18 at the upper end of the vessel.

In accordance with the invention the outlet communicates with the interior of the vessel through a fixed rigid tube 20 to the lower end of which is attached a flexible walled tube 22.

Normally the rigid fixed tube 20 will be of a relatively large diameter whilst the tube 22 will preferably be of a small diameter and to facilitate the joining of one to the other, an intermediate joining tube 24 is fitted into the lower end of the tube 20 and has secured to its other end the tube 22.

Attached to the flexible walled tube is a buoyancy device in the form of a hollow spherical bulb 26. As the water level denoted by reference numeral 28 rises so the spherical bulb 26 also rises and causes the flexible walled tube 22 to become kinked and this serves to close off the passage for air into the tube 20.

In order to ensure that the lower end of the tube 22 does not enter the liquid, it is stuck or otherwise secured or bonded to the tube 20 at point 30.

In the embodiment illustrated, the tube 22 has a nominal 3 mm bore and a wall thickness 0.5 mm and is of neoprene rubber. The intermediate tube 24 is a length of P.V.C. tubing having 6 mm overall diameter and formed at its lower end with a barb-like protrusion over which the rubber tube can be stretched and secured. To make the joint even more secure, a retaining clip or ring may be fitted around the tube behind the barb.

The intermediate tube 24 is bonded into the lower end of the fixed tube 20 and is retained in position by means of a suitable adhesive.

Alternatively the two tubes may be formed with complimentary screw thread profiles to allow the one to be screw threaded into the other.

Detail of the barbed end of the intermediate tube 24 is shown in Fig. 2. Here the barbed end is denoted by reference numeral 32 and a retaining clip 34 is shown to the rear of the barb.

From experiment it has been found that the position of the bulb 26 is one of the factors which determines the difference in the liquid levels between the point at which the tube 22 starts to become kinked and the point at which it becomes fully closed.

Using a neoprene rubber tube having dimensions referred to above and using as the floating shell a hollow spherical member 45 mm in diameter also formed from low density plastics material, and by locating the shell 26 approximately 5 centimetres from the end of the tube 22 secured to the barb 32, so the height difference between the liquid level at which the tube starts to become kinked and the level at which the tube is fully closed is approximately 5 mm.

This differential can be altered by varying the distance from the barb to which the shell 26 is attached and also by forming the tube 22 from a material which is less or more flexible.

The weight of the floating shell 26 is chosen sa as to be sufficient as to drag down the tube 22 and follow a falling liquid level so as to overcome any tendancy for the flexible walled tube 22 to take on a permanent set.

The maximum pressure to which the vending device can be subjected is limited by the force exerted by the external pressure (that is external to the vessel) on the flexible walled tube on the side of the "kink" which communicates with the outside of the vessel through the tube 20.

Although the invention has particular application in vessels designed to remove iron in solution or suspension in water supplies, it is to be understood that the invention is in no way limited to such applications and the invention may be applied to any venting device in any vessel containing a fluid having an interface with a second fluid at which the floating member can be located.

It will be appreciated that in a vessel in which iron is precipitated, it is inevitable that a certain amount of the iron will become deposited on the wall of the flexible walled tube. The deposit will normally be soft but if it does harden it has been found in practice that the hardened precipitate will flake from the wall of the tube as the latter flexes from one position to another.

The float will also acquire a build-up of deposit but since the float in the particular application will normally be surrounded by moving spheres the thickness of the deposit will be kept to a minimum. The weight of the deposit will obviously affect buoyancy of the floating shell 26 but it has been found in practice that this has little effect on the overall performance of the device.

Claims (11)

CLAIMS 1. A fluid vent for a vessel comprising a fixed outlet in the vessel at a high level, rigid fluid passage means communicating between the outlet and a lower point within the vessel, a flexible walled tube joined to the rigid fluid passage means at or near the said lower point and forming a 'U' bend with the remote end of the flexible walled tube secured at an elevated position within the vessel, and float means attached to or acting on the flexible walled tube forming the 'U' bend to cause the flexible walled tube to become kinked and to shut off the fluid passage through the outlet when the fluid level in the vessel exceeds a given height. 2. A fluid vent as claimed in claim 1 in which the flexible walled tube is formed from neoprene rubber. 3. A fluid vent as claimed in claim 2 in which the ratio of the diameter of the bore in the flexible walled tube to the wall thickness of the tube is 6.1. 4. A fluid vent as claimed in any of claims 1 to 3 in which the float means comprises a hollow spherical member having a specific gravity less than the specific gravity of the fluid so that the member will float thereon. 5. A fluid vent as claimed in claim 4 in which the float means is attached to the flexible walled tube by means of an adhesive. 6. Afluid vent as claimed in any of claims 1 to 5 in which the flexible walled tube is secured to the inside wall of the vessel or to the rigid fluid passage means. 7. A fluid vent as claimed in claim 6 in which the rigid passage comprises a length of rigid tubing which extends from a standard fitting secured in the wall of the vessel and the flexible walled tubing is secured to the lower end of the rigid tube. 8. A fluid vent for a vessel constructed arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings. New claims or amendments to claims filed on 2.10.80 Superseded claims 1 to 8 New or amended claims:

1. A fluid vent for a vessel containing a first fluid in a lower zone and a- second fluid in an upper zone above an interface with the first fluid, comprising a fixed outlet in the vessel at a high level in the upper zone, rigid fluid passage means communicating between the outlet and a lower point within the vessel adjacent the interface, a flexible walled tube joined to the rigid fluid passage means at or near the said lower point and forming a 'U' bend with the remote end of the flexible walled tube secured at an elevated position within the vessel in the upper zone thereof, and float means floating on the first fluid at the interface and attached to or acting on the flexible walled tube forming the 'U' bend to cause the flexible walled tube to become kinked and to shut off the passage for the second fluid through the flexible tube to the outlet when the level of the first fluid in the vessel exceeds a given height.

2. A fluid vent as claimed in claim 1, wherein the vessel has a single inlet for a mixture of the first and second fluids.

3. A fluid vent as claimed in claim 2, wherein the said inlet is located in the upper zone.

4. A fluid vent according to claim 2 or claim 3, wherein the said inlet is a liquid/gas inlet.

5. A fluid vent as claimed in any of claims 1 to 4 in which the flexible walled tube is formed from neoprene rubber.

6. A fluid vent as claimed in claim 5 in which the ratio of the diameter of the bore in the flexible walled tube to the wall thickness of the tube is 6.1.

7. A fluid vent as claimed in any of claims 1 to 6 in which the float means comprises a hollow spherical member having a specific gravity less than the specific gravity of the fluid so that the member will float thereon.

8. A fluid vent as claimed in claim 7 in which the float means is attached to the flexible walled tube by means of an adhesive.

9. A fluid vent as claimed in any of claims 1 to 8 in which the flexible walled tube is secured to the inside wall of the vessel or to the rigid fluid passage means.

10. A fluid vent as claimed in claim 9 in which the rigid passage comprises a length of rigid tubing which extends from a standard fitting secured in the wall of the vessel and the flexible walled tubing is secured to the lower end of the rigid tube.

11. A fluid vent for a vessel constructed arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.