GB2188360A - Insulated containers for liquids - Google Patents

Abstract

A generally rectangular tank for transport of liquid comprises an inner container 10 separated by an insulating foam layer 12 from an outer container 14. Both containers are formed by rotational moulding. The outer container is divided over a vertical plane into portions 16 and 18 which are assembled around the inner container 10 and sealed along seams 20 before foam is injected to produce the layer 12. The tank has within its overall contour a compartment 13 with a lid 45 for storage of equipment. A harness of webbing straps 48A to 48D provides for attachment of restraint ropes to hold the tank on a vehicle. <IMAGE>

Description

SPECIFICATION Insulated containers for liquids This invention relates to insulated containers for liquids.

It is knownto provide Iiquidstankswhich can be mounted on and secured to vehicles in orderto transport liquids needed for drinking and other purposes. In order to withstand shocks transmitted from the road surface and reduce weight they are often made from a polymeric material, such as polyethylene. For cold climates such tanks are often insulated by wrapping a layer of insulating material around the outside of the tank.

It has been proposed to thermally insulate a tank by incorporating a layer of foamed material in the wall ofthetankbutthe knowntechniqesfor manufacturing such atankwall are relatively complex.

The present invention provides a method of making an insulated tank in which an inner container for holding the liquid is formed from a synthetic plastics material, an outer container is formed from a synthetic plastics material and is disposed to enclose theinnercontainerwith agap betweenthe innerand outer containers and an insulating foam layer is formed in the gap between the inner and outer containers.

The foam layer may be formed by injecting afluid foam which then solidifies in situ or by introducing into the gap components of a mixture which react to form the foam.

The outercontainer may be made in two ormore partswhich are placed around the innercontainer and sealed together before the foam material is injected. Conveniently the inner and outer containers can each be formed by rotational moulding, in which case the outer container is then divided along a suitable line into two sections. The sections are brought back together to surround the inner container and welded along the dividing lineto form a sealed outer container, after which foam or foam-forming material is injected into the gap between the containers.

Preferably the outer skin is molded to have tool and accessory compartments within its contours. In this case, the inner skin is suitably moulded to accommodate the contours of compartments.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which Figure lisa perspective view of a tank according to the present invention; Figure2 is a longitudinal sectional view th rough the tank of Figure 1 on the line ll-ll; Figures3and4arescrap sections on the lines Ill-Ill and IV-IV, respectively, in Figure 1; Figure 5is a detail, partly in section, of a modified form of outlet for the tank; Figure 6is a partial sectional view ofthetankwall in a modified construction;; Figure 7 is a detail sectional view oftheformation of a filling opening in thetankwall, and Figure 8 is a transverse section of an alternative form of tank in accordance with the invention.

ThetankshowninFigures1 and2comprisesan inner polyethylene container 10, typically of 1,000 litre capacity, separated by a layer 12 of insulating foamed material from an outer polyethylene container 14. Thetank isof generally rectangular configuration but, as wili be described in more detail later, it has an external compartment 13, accommodated within the overall contour of the tank, which serves for storage of tools and/or ancillary equipment.

The inner container 10 and the outer container 14 are formed separately by rotational moulding. The outer container 14 is then divided along a vertical plane into two portions 16 and 18 by cutting through the wall ofthe container. The portions 16 and 18 are brought together around the inner container 10 and are welded together along the seam 20. The seam 20 could be closed by a butt weld but the preferred form of seam is as shown in Figure 3. The outer container 14 is initiallyformed with a peripheral groove and is cut along one wall of the groove so that the base of the groove forms a recessed flange 22 on the portion 16 which can then be fitted within the periphery 24of the portion 18 before a seam weld 26 is formed.The seam can be reinforced by a series of screws 28 joining the margin of the portion 18totheflange22.

With the outer container 14 re-sealed to enclose the inner container 10 the gap between them is filled with the insulating foam material 12 by injecting a liquid foam or a foam-forming mixture into the space and causing itto set a rigid or semi-rigid foam.

The compartment 13 isformed in the external surface of the outer container 14 and to accommodate this compartment the inner container 10 is of stepped formation with a reduced height at its left hand end (as seen in Figure 2). End wall 30 and side walls 32 and 34 ofthe compartment 13 are formed by a double layer of the container 14 between which the foam layer 12 extends. The end wall 30 has openingsforan inlet pipe 36 and a handle 37 of a pump 38. The pump 38 delivers the liquid to be stored in the tank, through a filter mounted in the compartment 13 but not shown in the drawing, to an inlet pipe 39 which is mounted in a screwed cap 40 andextendsthroughthetankwalltothe bottom of the tank interior. A vent 41 is formed alongside the inlet pipe 39.The outlets 42 from the tank are arranged in an opening 43 closed by a plug 44.

The compartment 13 also provides spacefortools and ancillary equipment which may be placed in it loose or in blocks of packing material shaped to receive the tools and prevent them from moving around. A lid 45 is provided to coverthe compartment 13. The lid 45 is hinged so that it can swing (as shown by arrow 46 in Figure 2)to an open position flat against the top of the adjacent part of the tank.

To allow the tankto be securely fastened to a vehicle or other mounting, the outer container 14 is formed with grooves 47 (Figure 4) to accommodate webbing straps 48. The straps form a harness which comprises a strap 48A encircling the sides ofthetank and straps 48B, 48C, and 48D passing around the tank perpendicularto the strap 48A. Strap 48B passes through slots in the side walls 32 and 34 and across the bottom of the compartment 13. The strap 48C passes underthe lid 45. The harness is provided with tabs 49 to which restraint ropes 50 can be attached.

In a modification shown in Figure Sthetankis provided with a 'self-sealing' drain hole 52 located in a lower part of one ofthe sides of the tank. Asealing member 54 closes the inner end of the hole 52to prevent liquid in the tankfrom flowing out therethrough. The differential pressure exerted by the head of liquid in the tank serves to reinforce this sealing action. When a spigot 56 is inserted into the hole 52 it pushes the seal 54 out ofsealing contact with the wall of the inner container 10 and allows liquid to flow from the tank. Removal ofthe spigot 56 allows the sealing member 54to reassume its sealing position.The outer surface of the spigot 56 seals againstthe wall of the hole 52.

The inner container 10 in the vicinity of the hole 52 is recessed and the walls 58 of the passage constituting the opening are inclined in orderto prevent a build-up of liquid after use of the spigot 56 which might freeze and cause a blockage. A hinged drain cover 60 is also provided to form an insulating plug forthe hole 52.

Figure 6 shows a modification in which spacing protrusions 61 are moulded in the inner container 10.

These protrusions 61 stand sufficiently proud of the remainder ofthe outer surface of the inner container 10 thatthey act as feed resting on the surrounding outer skin 14. In this way the distance between the outer skin 14 and inner container 10 is set without having to rely on the insulating foam 12 maintaining the innercontainer 10 in spaced relationship with the outer container 14. Alternatively blocks of foam may be positioned to hold the two skins apart and then the areas between the blocks foam filled thus removing weak points in the insulation and making the mould easiertofabricate.

lnordertoprovideamainopening inthetank,the inner container may be provided with a protruding collar 62 which is shown in Figure 7. By moulding or cutting a corresponding hole in the outer skin 14the flange 63 of the collar 62 may be welded or otherwise sealingly secured to the outer skin 14 such thatthe foam 12 is not liable to contamination by water etc.

which would serve to undermine its insulating properties.

Afurther embodiment of the invention, illustrated in Figure 8, comprises a steel cage 64 which surrounds the inner container lOin order to givethe tank a more rigid construction which is betterableto withstand rugged use. The cage 64 lies immediately between the inner container 10 and the insulating material 12. Legs 65 protrude through the bottom of the outer skin 14from the cage64tosupportthetank structure. Each leg 65 is sealed at its junction with the outer skin 14. Eyelets 66, secured to the sides of the cage 64, protrude through the sides of the outer skin 14 by which the tank structure may be secured in place.

This embodiment also shows an alternative disposition oftool compartments 68 and 69 which are of generallytriangularvertical section, extend along the sides of the tank, and have lids 70 and 71.

Claims (12)

1. A method of making an insulated tank in which an inner container for holding the liquid is formed from a synthetic plastics material, an outer container is formed from a synthetic plastics material and is disposed to enclose the innercontainerwith a gap between the inner and outer containers and an insulating foam layer is formed in the gap between the inner and outer containers.

2. A method as claimed in claim 1 in which the outer container is sealed before fluid foam or a foam-generating mixture is injected into the gap.

3. A method as claimed in claim 1 or 2 in which the inner and outer containers are formed by rotational moulding.

4. A method as claimed in claim 3 in which the outer container is moulded with a groove and is divided along onewall of the groove so that the parts can be reassembled around the inner container with an overlap between their edges to facilitate sealing.

5. A method as claimed in any of claims 1 to 4in which the inner container is formed with protuberances to engage the outer container and determine the spacing between the containers.

6. A method as claimed in any of the preceding claims in which the inner container is formed with an opening surrounded by an outwardly-extending flanged collar, whose flange is welded into an opening in the outer container.

7. A method as claimed in any of the preceding claims in which the outer container is formed with encircling grooves to receive straps for mounting of the tank.

8. An insulated tank produced by the method of any of the preceding claims.

9. Atank as claimed in claim 8 having a recess formed within its contours to accommodate tools and/or ancillary equipment.

10. Atank as claimed in claim 9 in which the recess is provided with a lid.

11. A dou ble-walled insulated tank having grooves in its outer surface accommodating a harness of strapping by means of which the tank can be fastened to a vehicle.

12. Atankas claimed in claim 11 which isof generally rectangular shape and has a harness comprising a strap encircling the sides and ends and a pluralityofstraps extending aroundthetop and bottom and the side walls.