Gas Flush Troubleshooting: Why Your Modified Atmosphere Packaging System Is Failing
Modified Atmosphere Packaging replaces the oxygen inside a sealed package with a controlled mixture of gases, typically nitrogen, carbon dioxide, or a combination of both, to slow bacterial growth, prevent oxidation, and extend product shelf life without chemical preservatives. When the MAP system on a chamber sealer fails, the consequence is not simply a mechanical fault. Products sealed with incorrect gas ratios or with oxygen displacement that did not occur will spoil faster, and in a commercial food business, that represents both a direct financial loss and a food safety risk.
Diagnosing MAP system failures requires working through the gas delivery circuit methodically: from the gas supply through the regulator and flow meter to the solenoid valve and into the chamber. Our Walvis Bay workshop carries out MAP system diagnosis and component repair for chamber sealers serving butcheries, food processors, and catering operations across Namibia. Our staff communicate in both English and Afrikaans.
Gas Flush Valve Faults in Chamber Sealers: Solenoid Diagnosis
The gas flush solenoid valve is the component that controls when gas enters the chamber during the sealing cycle. It receives a signal from the machine’s control board at the correct point in the cycle, opens to allow gas flow into the evacuated chamber, holds for the duration of the flush period, and closes before the sealing element fires. A solenoid valve that fails to open, opens intermittently, or does not close fully will produce MAP failures that are difficult to diagnose without component-level testing.
The most common solenoid failure modes are coil burnout, which causes a complete failure to open, and mechanical sticking caused by particulate contamination or internal corrosion. A coil burnout can be confirmed with a basic resistance check across the solenoid terminals. An open circuit reading confirms coil failure and requires solenoid replacement. A correct resistance reading that is still not producing valve actuation points to a control board fault: the solenoid is functional but is not receiving the correct trigger signal.
Mechanical sticking is more difficult to diagnose through electrical testing alone. A solenoid that has correct electrical properties but still fails to open under operating conditions should be removed, inspected for internal debris, and tested by direct actuation if the valve design permits it. Sealers used for meat packaging are particularly susceptible to solenoid contamination because fine particles from meat processing can enter the gas system through line contamination.
Incorrect Gas Ratios in MAP Packaging: Flow Meter and Regulator Checks
Achieving the correct gas atmosphere inside a sealed package depends on two variables: the volume of gas delivered during the flush cycle, and the ratio between gases in multi-gas applications. Both of these are controlled upstream of the solenoid valve by the gas regulator and flow meter.
A gas regulator that has drifted from its set point delivers gas at a different pressure than the machine’s control system expects. Because flow through the solenoid valve at a given opening duration is pressure-dependent, a regulator delivering lower than specified pressure will result in under-flushing, meaning the chamber receives less gas than required and residual oxygen levels remain above the target. A regulator delivering higher than specified pressure causes over-flushing, which wastes gas and may affect bag integrity.
Check the regulator output pressure against the specification in the machine documentation or the value set during initial commissioning. Regulator drift is a gradual process and may not be apparent from the machine’s cycle behaviour until residual oxygen testing reveals a consistent deviation from target.
Flow meters on multi-gas MAP systems control the ratio between gas streams. A flow meter with a contaminated or damaged float will produce inaccurate flow readings and incorrect gas ratios. For butcheries and meat processors using nitrogen and CO2 combinations, incorrect ratios produce the correct visual appearance of a sealed package but incorrect atmospheric composition, which shortens shelf life and may affect product colour.
Residual oxygen measurement using a calibrated oxygen analyser is the only reliable method for confirming that MAP settings are producing the correct package atmosphere. Visual inspection of the sealed package does not confirm gas composition.
CO2 and Nitrogen MAP Combinations: Troubleshooting for Meat Packers
Meat packaging applications commonly use a mixture of CO2 and nitrogen, sometimes with a small percentage of oxygen retained to preserve fresh meat colour. The exact ratio depends on the product, the target shelf life, and the cold chain conditions.
CO2 at the concentrations used in meat MAP is absorbed into the product surface over time, which causes the package to appear slightly deflated after sealing even when the gas flush was correctly applied. This is normal behaviour for CO2-inclusive MAP applications and should not be diagnosed as a seal failure. Operators unfamiliar with this characteristic sometimes adjust MAP settings incorrectly in response to the apparent volume reduction.
A genuine seal failure in a MAP application presents differently: the package is soft and inflated with room air, the product surface shows early discolouration, and shelf life is substantially reduced compared to correctly sealed batches. If seal integrity is uncertain, the food safety and vacuum seal testing guide covers the practical seal integrity tests available to food businesses without laboratory equipment.
For businesses packaging biltong or droewors, MAP applications using nitrogen are used to extend shelf life beyond what vacuum sealing alone achieves. The specific requirements for biltong and droewors vacuum packaging are addressed separately, including the interaction between product moisture content and the MAP cycle.
Our workshop carries out gas system diagnosis, solenoid valve replacement, and flow meter inspection for MAP-equipped chamber sealers. Customers outside Walvis Bay can use our courier repair service.