AU661193B2

AU661193B2 - Pressure relief IBC

Info

Publication number: AU661193B2
Application number: AU46128/93A
Authority: AU
Inventors: Charles Sidney Futerman
Original assignee: Mulox IBC Ltd
Current assignee: Rexam DFR China Ltd
Priority date: 1992-09-08
Filing date: 1993-09-07
Publication date: 1995-07-13
Anticipated expiration: 2013-09-07
Also published as: ZA936625B; CA2105742A1; AU4612893A; GB9218970D0; EP0586994A1

Description

661193 p00 Regulation 3.2

AUSTRALIA

Patents Act, 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Original

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TO BE COMPLETED BY THE APPLICANT S' NAME OF APPLICANT: MULOX IBC LIMITED ACTUAL INVENTOR: ADDRESS FOR SERVICE: INVENTION TITLE: CHARLES SIDNEY FUTERMAN Peter Maxwell Associates Blaxland House, Suite 10, 5 Ross Street, NORTH PARRAMATTA NSW 2151 PRESSURE RELIEF IBC The following statement is a full description of this invention, including the best method of performing it know to me:- This invention relates to container bags and in particular relates to container bags for carrying loads in the range of one half to two tonnes and known as flexible intermediate bulk containers (FIBC's).

Flexible intermediate bulk containers are increasingly employed in cargo handling and transporting situations, especially for the carriage of particulate or pulverulent material. A typical FIBC will be manufactured from a fabric woven from a polyolefin *0 tape and have integral lifting loops. Examples of such 0* containers are described in UK patent numbers 1591091 and 2063816. FIBC's have to meet various national and international safety standards; for example, it is normal to require a five to one safety ratio, that is an IBC rated at one tonne should not break under loads of less than five tonnes.

A recent trend in the FIBC field has been the increasing usage of extrusion coated fabrics in the manufacture of FIBC's to give moisture resistance without the requirement of a separate 2t polyethylene liner. Extrusion coated FIBC's are not completely waterproof owing to the holes created by needle penetration during sewing in making up. However, designs for extrusion coated FIBC's have been proposed wherein very fine threads are employed and stuffer threads are used to fill the needle holes thereby giving much improved resistance to the passage of air water or vapour.

More and more users are inflating the FIBC's prior to filling which is good practice to ensure even filling. For various reasons some users are inflating FIBC's to very high pressures and, in the absence of a polythene liner, the pressurised air can force its way through the finest of stitching and, where the filling product is a fine powder, entrained powder can be taken through with the air thus affecting the environment in the region of the filling machines. This is an especial S -2problem where the contents are chemicals or fertilisers which may be noxious or otherwise harmful.

The invention seeks to provide a container bag improved in the above respect.

According to one aspect of the invention there is provided a flexible intermediate container apparatus adapted to contain a pulverulent material, said container apparatus comprising: a bag formed of a plurality of side walls, a base wall, and a top wall defining an interior space closed from ambient atmosphere; a pressure means for producing pressure within said bag above said ambient atmosphere; a spout mounted on said top wall constructed to receive 15 said pulverulent material housed in a filling apparatus that is closed from ambient atmosphere; a pressure relief valve mounted on a wall of said bag and adapted to release gas and said pulverulent at a pressure lower than that which would cause the walls of said bag to 20 leak; and o duct means being provided having one end thereof connected to said pressure relief valve to collect said pulverulent material which may escape from sad pressure relief valve, and the other end sealingly positioned to deposit the escaped pulverulent material into a suitable receiver that is closed from ambient atmosphere such that said container apparatus can fill said bag with no leakage of u A L l dat Spulverulent material into said ambient atmosphere.

r^ plvuen -2a- According to another aspect of the invention there is provided a method for filling a flexible intermediate container with a pulverulent material, the container comprising a bag formed of a plurality of side walls, a base wall, and a top wall; a spout mounted on the top wall adapted to receive the pulverulent material from a filling apparatus; a pressure relief valve mounted on a wall of the bag and adapted to release gas and the pulverulent material at a pressure lower than that which would cause the walls of the bag to leak, wherein duct means is provided having one end thereof connected to the pressure relief valve to collect the pulverulent material which may escape from the pressure relief valve, and the other end positioned to deposit the escaped pulverulent material into a suitable receiver, said 15 method comprising the steps of: introducing a compressed gas into the container; and introducing a pulverulent material into the spout from a filling silo positioned above the bag, thereby filling the bag with the pulverulent material.

20 The pressure relief valve can be set to give a desired inflation pressure in the FIBC but will permit air to escape above this pressure thereby ensuring that the stitching and seams of the FIBC are not over-stressed to the point of leakage. Preferably, the receiver is the filling silo so that any expelled powder is returned for refilling.

The pressure relief valve can be located anywhere on the FIBC but ideally is positioned on the top edge either A along the edge where the top is attached to the body of the I -2b- FIBC or in one of the corners of the top edge, for the convenience of attaching the tube thereto to lead vented gases and any entrained powder to the receiver. The pressure relief valve can be of various types as conventionally known and can be either sewn in, welded or glued into the fabric.

In an alternative construction, the valve is present on a tube or the like associated with the filling machine, and the FIBC is simply provided with means connectible to the valve, e.g. a disc or other area capable of receiving the valve. In this way the number of valves required is greatly reduced.

S

o -3- The FIBC of the invention may be otherwise any of the conventionally known types but will normally be extrusion coated to render it air or water tight. The invention is equally applicable to FIBC's having or not having a liner e.g.

of polyethylene sheet material.

The fabric from which the FIBC of the invention is formed may be a conventional fabric for use in this type of container and may be woven from polyethylene or polypropylene tape yarns or polyester coated yarns. The side walls of the container may be made from a fabric having reinforced zones or areas of interwoven reinforcing yarns for example as disclosed in our UK goof*: patent number 1591091 to which the lifting loops will normally be attached. The lifting loops will preferably be of a woven 0 webbing of synthetic yarns, for example of the type used for o*00 car seat belts, for example polypropylene, polyamide or polyester yarns, or may be ropes or hawsers of suitable strength.

:2.0 The container bag of the invention may be fitted with a top S and/or a filling spout, as well as a discharge spout, as is conventional in the FIBC art.

The invention will be described further, moreover by example, 25 with reference to the accompanying drawings, in which: *Go Figure 1 is a perspective view of an FIBd of the invention; Figure 2 is a detail from Figure 1; and Figure 3 is a similar view to Figure 1 illustrating the filling process.

Referring to the drawings, an FIBC generally designated 10 has side walls 12 and a base 14. The fabric from which the side walls and base are formed will generally be a woven polyolefin -4fabric which has been extrusion coated to render it air and water resistant. Lifting loops 16 are provided across each corner and are stitched to respective side walls (which may contain reinforced zones to which the lifting loop 16 are attached). The stitching is preferably carried out in such a way as to minimise leakage, e.g. by use of fine threads and stuffer threads.

The bag 10 has a top 18 with a filler spout 20 as is conventional in this field.

*i 'em In accordance with the invention, a pressure relief valve 22 is sewn, glued or welded into the bag fabric comprising the top 18 adjacent one corner. The pressure relief valve 22 has means 5 e1" 24 connectible to a pipe or tube 26 (see Figure 3) for ducting exhausted gases and entrained powder to a receiver.

As- can be seen from Figure 3, when the bag 10 is being filled the spout 20 is connected to a filling silo 28. Before or during the filling of the bag air, or other gas such as 00 nitrogen, under pressure, is forced into the bag thereby inflating it, and filling of the pulverulent or powdery material commences. If the pressure within the bag exceeds the predetermined setting of the relief valve 22 (which should be chosen to be below the pressure at which air will be forced through the seams of the bag 10) excess air is ducted via the tube 26 back into the silo so that any entrained powder is returned for re-use instead of being released into the atmosphere. Alternatively, the tube 26 could be led to another suitable receiver whereby the entrained powder is kept out of the atmosphere surrounding the filling machine, or could even be vented to waste if circumstances dictate this.

The FIBC of the invention provides a simple and economical solution to the problem of leakage at filling stations where high pressure inflation is employed.

Claims

1. A flexible intermediate container apparatus adapted to contain a pulverulent material, said container apparatus comprising: a bag formed of a plurality of side walls, a base wall, and a top wall defining an interior space closed from ambient atmosphere; a pressure means for producing pressure within said bag above said ambient atmosphere; i..sa a spout mounted on said top wall constructed to receive said pulverulent material housed in a filling apparatus that is closed from ambient atmosphere; a pressure relief valve mounted on a wall of said bag and adapted to release gas and said pulverulent at a pressure lower than that which would cause the walls of said bag to •goS leak; and duct means being provided having one end thereof connected to said pressure relief valve to collect said pulverulent material which may escape from said pressure relief valve, and the other end sealingly positioned to deposit the escaped pulverulent material into a suitable receiver that is closed from ambient atmosphere such that said container apparatus can fill said bag with no leakage of pulverulent material into said ambient atmosphere.

2. A flexible intermediate container apparatus according to claim 1, wherein said bag is constructed from a woven fabric which is air and water resistant. -6-

3. A flexible intermediate container apparatus according to claim 2, wherein said fabric has a plastic material coating thereon.

4. A flexible intermediate container apparatus according to claim 1i, wherein a filling silo is both said fAlling apparatus and said suitable receiver.

A flexible intermediate container apparatus according to claim 1, wherein said pressure relief valve is at an edge i of said top wall.

6. A method for filling a flexible intermediate container with a pulverulent material, the container comprising a bag formed of a plurality of side walls, a base wall, and a top wall; a spout mounted on the top wall adapted to receive the pulverulent material from a filling apparatus; a pressure relief valve mounted on a wall of the bag and adapted to release gas and the pulverulent material at a pressure lower than that which would cause the walls of the bag to leak, wherein duct means is provided having one end thereof connected to the pressure relief valve to collect the pulverulent material which may escape from the pressure relief valve, and the other end positioned to deposit the escaped pulverulent material into a suitable receiver, said method comprising the steps of: V ^introducing a compressed gas into the container; and -7- introducing a pulverulent material into the spou+ from a filling silo positioned above the bag, thereby filling the bag with the pulverulent material.

7. A method according to claim 6, wherein the compressed gas is introduced into the bag prior to the introduction of the plverulent material.

8. A method according to claim 6, wherein the compressed gas is introduced into the bag simultaneously with the introduction of the pulverulent material. S9. A method according to claim 6, wherein one end of the duct means is connected to the filling silo, and wherein compressed gas and pulverulent material which escapes from the pressure relief valve is returned to the filling silo. 0* A flexible intermediate container apparatus adapted to contain a pulverulent material substantially as hereinbefore described with reference to the accompanying drawings. DATED this 10th day of April, 1995, MULOX IBC LIMITED Patent Attorneys for the Applicant: PETER MAXWELL ASSOCIATES 14 %4 ABSTRACT A container bag (10) designed to be inflated before or during filling characterised in that a pressure relief valve (22) is incorporated or incorporatable into the bag body, the valve being connectible to a receiver for exhausted powder or pulverulent matter. The pressure relief valve can be set to give a desired inflation pressure in the FIBC but will permit air to escape above this pressure thereby ensuring that the stitching and seams of the FIBC are not over-stressed to the O point of leakage. The valve is connectible to, and preferably is connected to, a receiver for any vented gases and entrained powder. Preferably the receiver is the filling silo (28) so that any expelled powder is returned for refilling. .0 00 6 O S S. S