Leakage checking for MAP inert gas packages inline

Automatic inspection of entire production is now available as the state of the art: random testing is the alternative

Resolution to quality control issues within the food industry, when product is packed in a modified atmosphere (MAP).

If a customer files a complaint regarding spoiled goods or a call-back threatens, the costs may amount to far more than just the value of the returned goods.

For this reason nearly all suppliers use testing procedures to detect leaks before they leave the plant.

If "leaks" are present in the package, the inert gas escapes, allowing the product to spoil within a very short time.

Crumbs, drops of sauce or grease spatters on the sealing surface are particularly troublesome.

Either random samples or entire production lots are tested.

Industry has developed suitable equipment and procedures for both methods.

Testing is either accomplished manually offline or automatically inline.

WATER TEST.

The simplest method for occasional single tests is a water bath: The unit to be tested is submerged in the bath manually - if bubbles rise, the package shows a leak.

This procedure is inexpensive, however not very practical for comprehensive leak tests.

Nevertheless this method is acceptable for simple applications and has the advantage, that no detection gas is required.

This testing method is therefore suitable as a supplement to CO2 tests - it identifies where the leak is - and also allows packages to be tested, which do not contain CO2.

TRACE GAS TEST.

Finer methods use tracer gases.

Equipment which operates with expensive helium or dangerous hydrogen is not acceptable in all plants for obvious reasons; but necessary to use tracer gases.

Testing with CO2 is considered the better alternative: this gas is necessary in most cases when checking for growth of mould and bacteria, and is comparatively uncomplicated and safe to handle.

On the other hand many foodstuffs generate CO2 themselves, which can be measured - making it an ideal test gas.

The test equipment operates with chambers in which the products are put into individually or in a collective container.

When the vacuum is drawn the CO2 sensors detect even the smallest gas leaks right down to ppm range (parts per million).

This is accomplished without contact and is non-destructive; no waste occurs.

High performance equipment offers reaction times as low as one second and does not require calibration.

How much does a return cost?.

Presently most companies use a central testing unit for offline random sample testing.

Production experts estimate the branch average of improperly packaged goods to be approx.

3 to 5 percent.

This is only an example for calculation: Generally it is necessary to consider how high the reject rate is between two tests or how high the costs are against customer returns.

In most cases the costs of the equipment is potentially recovered against the first batch of faulty goods.

Although if it were shipped and returned, the damage to the image of the company would be incalculable.

But regardless of how short the testing frequency is: any company, that wants to continuously supply perfect goods to their customers, cannot avoid complete testing of the entire output.

This could be accomplished offline; however the organisational and personnel costs would be considerable.

INLINE LEAKAGE TEST.

For this reason most companies, and suppliers to large retail chains are testing their entire production to an increasing extent.

For approximately one year the industry has also provided the technical pre-requisites for such testing.

To date the only manufacturer capable of performing reliable CO2 leak tests inline at a rate of up to 15 cycles per minute is the German company Witt-Gasetechnik.

The equipment (trade name "Leak-Master MAPMAX") operates in conjunction with all traysealer and thermoformer packaging machines.

The entire output from the machine is tested.

When horizontal or vertical flow wrap packs are used it is possible to test entire cases.

Product feed, testing and transfer of the goods are accomplished fully automatically at the subsequent station.

The equipment can be coupled with pushers using volt free contact to allow rejects to be sorted out without human intervention.

All measured data is available for further evaluation or as a log for proof of the quality for the customer.

With the availability of fully automatic inline testing equipment to match the requirements of the packaging machines, quality control has reached its present peak.

Every processor of foodstuffs is therefore in a position to guarantee top quality without reservations - and to gain a competitive advantage for themselves.

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