The present invention relates to sealing means, in particular to sealing means for use in air-blast heat exchangers.

In conventional air-blast coolers, sealing is effected by soldering or welding cooling tubes to reservoirs. Such sealing means is labour intensive and thus expensive, is unreliable and is easily damaged when the cooling system is subjected to vibration or thermal shock. In addition, such traditional cooling systems cannot easily be adapted or modified after manufacture and faulty tubes cannot easily be replaced.

According to a first aspect of the present invention there is provided sealing means for sealing a junction between a tank for containing fluid material and a tube in communication with the tank interior in an air-blast cooler, the sealing means comprising a sealing member of elastomeric material around the tube adjacent to the junction, means for compressing the sealing member so as to seal the junction against leakage of the fluid material, and means limiting or preventing movement of the sealing member laterally of the compression force to enhance the seal.

The sealing member is preferably substantially planar and is provided with holes through which the cooling tube passes.

Compression may be effected by a clamp. In one embodiment, a clamping bolt passes through a hole in the sealing member. In another, a clamping bolt is provided spaced from the sealing member. In yet a further embodiment, a strongback could be provided to apply the clamping force. The means for limiting movement of the sealing member may be provided by an abutment at the perimeter of the sealing member.

According to a second aspect of the present invention, there is provided a method of sealing the cooling tubes to a

reservoir in an air-blast cooler using elastomeric sealing means through which the tubes pass to communicate with the interior of the reservoir, the method comprising applying a clamping force to the sealing means while restraining the sealing means against outward displacement substantially perpendicular to the direction of the clamping force in a manner so as to cause the sealing means to seal against the outer tube surfaces and to seal the interior of the reservoir from the exterior thereof other than through the tubes .

The clamping force may be provided, in part, through a substantially non-deformable clamping member forming a surface part of the reservoir , the tubes also passing through this clamping member.

The elastomeric sealing means preferably comprises a planar elastomeric sealing member restrained about the perimeter against outward deformation.

The invention al s o provide s air-bl as t cooler s respectively incorporating the sealing means of the first aspect or formed according to the method of the second aspect of the present invention.

It will be seen that when the fluid being handled by the radiator is toxic or f lammable it is particularly important to minimise any possibility of leakage into the atmosphere .

According to a third aspect of the present invention , there is provided sealing means for a junction between two members communicating fluid materials internally one with the other, the sealing means comprising at least two seals spaced one from the other by a gap and drain means in fluid communication with the gap to provide a controlled leakage path for fluid material .

According to a preferred embodiment of the third aspect of the present invention, there is provided sealing means for sealing a j unction between a tank f or containing fluid material and a tube in communication with the tank interior in an air blast cooler, the sealing means comprising at least two

seals arranged around the tube adjacent to the junction and being spaced in the axial direction of the tube by a gap, the sealing means having drain means in fluid communication with the gap to provide a controlled leakage path for fluid material leaking from the tank.

Preferably, the seals are made of elastomeric material and are advantageously constructed according to the first aspect of the invention.

However, seals according to the third aspect may also be soldered or welded joints or any other seal.

The invention will now be described, by way of example, with reference to the accompany drawings in which:

Figure 1 shows at its left and right hand side respectively a first and second embodiment of a sealing arrangement in accordance with the first aspect of the invention.

Fig. 2 is a cross section showing a header tank for an air blast radiator with a sealing arrangement according to the third aspect of the invention; and

Fig. 3 is a cross section to a larger scale of a part of Fig. 2.

Common to both embodiments in Figure 1 are cooling tubes 3, each of which projects through aligned holes in a tube plate 2 and an overlying sealing member 4 into a tank 1. In practice, many such cooling tubes 3 are provided of which only one is shown. The cooling tube 3 has cooling fins 34 beneath the tube plate 2.

In the first sealing arrangement, as illustrated to the left of the Figure 1, the tank 1 comprises a pressure plate 9 constituting the floor of the tank and provided with holes through which the cooling tubes project, and a top cover 26. The top cover has a top and side walls with an outwardly projecting flange 35. A cover seal 27 is provided between the pressure plate 9 and the flange 35 of the top cover 26. Clamping bolts 28 ^{^} spaced around the pressure 'plate extend through aligned apertures in the flange, the cover seal, the pressure plate, the sealing member and the tube plate, and a

nut received on the bolt is tightened to hold all these parts together and to compress the sealing member 4. The tube plate 2 has flanges around its perimeter to provide a step forming a retaining surface 33 for the perimeter of the sealing member . The sealing member 4 is made of an elastomeric material such as rubber so that as the clamping bolt 28 is tightened, the compression of the sealing member 4, retained by the retaining surface 33, causes the sealing member to be forced against the outer wall of the cooling tube 3 to seal the junction of the tube 3 with the tank 1.

In the second sealing arrangement shown to the right of Figure 1, the tank 1 is formed as one part from a hollow tubular extrusion. The base of this tubular extrusion is drilled with an appropriate hole pattern to receive the cooling tubes. In this second arrangement, the clamping bolts 28 take the form of studs 30 and lugs 31 welded respectively to the tube plate 2 and the tank 1. The perimeter of the sealing member 4 is retained in this embodiment by a skirt 32 fixed to and projecting down from the outside of the tank 1. Thus, when clamping pressure is applied, the sealing member is again forced against the outer wall of the cooling tube 3, thus sealing it against leakage from the tank 1.

The clamping arrangement in this second embodiment could of course be located outside the flange 29 and the retaining means be provided by the flange retaining surface 33, in the same manner as in the first arrangement described above.

The tank 1 and the tube plate 2 are formed from standard steel sections and plates. Aluminium sections or castings could be used instead. In all cases, end caps (not shown) are fixed to opposite ends of the sections to complete the tank 1.

This arrangement allows the cooling tubes 3 some freedom of movement with respect to the tanks 1 so as to absorb the stresses introduced by expansion or contraction, or due to vibrations. Such movement is of course limited by the positioning of the cooling tube fins 34.

The same sealing means would be used to advantage at the junction between the cooling tubes and a collector tank

and/or at the junction between the cooling tubes and a feeder tank.

In Fig. 2 two different constructions of the header tank are shown to the left and right hand sides of the Figure respectively.

Type A (to the right) has a header tank 1 in the form of a "U" section. Type B (to the left) has a header tank 1 in the form of a box section.

Tube plate 2 is drilled to accept a number of tubes 3 which are in fluid communication with the header tank 1. The tubes may be plain or finned. A bottom sealing member 4 made of elastomeric material is sandwiched between the tube plate 2 and a bottom seal plate 5. Compression of bottom sealing member 4 causes it to seal against the tubes 3 to provide a bottom seal.

An air gap 6 is created by spacers 23 between bottom seal plate 5 and an upper seal plate 7. A top sealing member 8 is sandwiched between the upper seal plate 7 and either a top seal plate 9 in the type A header tank (right hand side) or the bottom of the header tank 1 in the type B header tank (left hand side). The top sealing member 8 is preferably identical to the bottom sealing member 4. It is advantageously made of elastomeric material and when compressed forms an efficient top seal against tubes 3.

As can be seen from Fig. 1, if the top seal fails then fluid in the tank 1 escapes into air gap 6. It is prevented from escape into the atmosphere by the bottom seal and is drained from the air gap 6 by a drain connection 21 into a secure vessel or drain. The advantages of this arrangement for handling dangerous fluids are obvious.

Compression of the sealing members 4 and 8, to ensure that they seal effectively against the periphery of the tubes 3, is effected by tightening a tube seal compression nut 16 on a spacer stud 11. The lower flange 12 of spacer stud 11 then exerts a compression force on the top and bottom seals. Stud 11 may alternatively be a straight stud with a spacer collar fitted.

In the type A header tank, the tank 1 is sealed at its lower edge against the top seal plate 9 by a tank edge seal 10. In type B, the top seal plate is integral with tank 1.

A further seal is shown in Fig. 1 and more clearly illustrated to a larger scale in Fig. 2. This provides security against leakage of the tank edge seal 10. A second flange 12A on spacer stud 11 abuts a tank seal bottom strip 13. An elastomeric tank sealing member 14 is sandwiched between the bottom strip 13 and a top strip 15 and is compressed by means of a tank seal compression nut 17. Any leakage from tank seal 10 is thus prevented by this further seal from reaching the atmosphere and can be drained from controlled leakage space, or air gap 24 by tank seal drain connection 22.

A similar arrangement is shown for the type B tank to protect against leakage of the seal against the bottom plate of the header tank.

It can be seen that this construction allows independent control of the sealing pressures for the tube seal and the tank seal. This feature is particularly useful.

Damage to the holes in the sealing members can be minimised if the threaded portions of the spacer stud 11 are of smaller diameter than the plain portion, as illustrated.

The sealing members 4, 8, 10 and 14 are preferably of elastomeric material but need not be all of the same material within a single unit. The arrangement would also be advantageous for seals constructed by soldering or welding or of any other form and of course has applications to constructions other than air blast radiators. The elastomeric seals as described in the co-pending UK Patent Application 92 06 588.7 are preferred because they are reliable and facilitate maintenance work on the tubes etc.

The header tank 1 is secured by studs or bolts and nuts (not shown) through tank securing lugs 18 and 19. It may alternatively be secured by an extended from of spacer stud 11 passing through the top tank securing lug 19, or by a butt strap or indeed by any suitable means.