Stability of metrological gas mixtures: how to manage and ensure operational continuity

For a gas mixture to maintain its analytical reliability, it must be used within well-defined time limits. Managing stability properly means preventing errors, avoiding process interruptions, and ensuring consistent data quality.

This article explains how to organize effective monitoring of the stability of metrological gas mixtures, with practical guidance to support continuity in analytical and production processes.

What does “stability” mean for a metrological mixture?

Metrological gas mixtures are certified products with defined stability over a specific time interval. “Stability” indicates the date beyond which the producer no longer guarantees the declared specifications, including concentrations and tolerances.

This date is determined by several factors:

• Chemical reactivity of the components: some may decompose or react over time, affecting the certified concentration.
• Cylinder materials and technology: internal linings and valves can influence gas-surface interactions.
• Storage conditions: temperature, humidity, and light exposure all affect mixture stability.
• Experimental data from the producer: long-term tests and field data help determine the actual useful life of the mixture.

Using a mixture beyond its guaranteed stability date carries the risk of unreliable or non-reproducible data. Stability must therefore be managed with the same care as any other critical process parameter.

Building an effective stability management system

Effective management requires visibility, traceability, and planning. Digital tools can provide strong support, but a clear operating procedure must come first. Key elements include:

1. Centralized registration

Each new mixture should be logged in a centralized system, recording:

• Batch number;
• Concentration;
• Stability guarantee;
• Physical location;
• Assigned user or department.           

A well-structured database makes it possible to monitor the status of all mixtures in use and in storage.

2. Automatic monitoring of stability dates

Software alerts that flag approaching end-of-stability dates allow timely planning of replacements. In smaller setups, a spreadsheet with automated formulas may suffice, while in more complex environments integration with quality or inventory management systems is recommended. 

3. Rotation and reordering policies

Mixtures should follow the FIFO (First In, First Out) principle: the first to enter storage should be the first to be used, reducing the risk of expired cylinders.

It is also advisable to set reorder thresholds based on supplier lead times, ensuring new mixtures arrive before critical ones expire.

4. Clear and accessible labeling

Each cylinder must display the stability guarantee date and other key identification details.

In facilities using many mixtures, color coding or QR labels can simplify quick checks.

Preventing operational interruptions

To ensure continuity, a proactive rather than reactive approach is essential. 

Careful stock control, combined with strong supplier collaboration, plays a key role in preventing process disruptions.

Managing critical mixtures

Some mixtures are vital for quality control, safety, or calibration of key instruments.

If their absence or degradation could compromise operations, they should be classified as critical mixtures.

In such cases, stricter management rules are advisable, such as maintaining a minimum stock level or prioritizing reorders. 

Supplier collaboration

Accredited suppliers of metrological mixtures can offer scheduled deliveries or framework contracts that ensure constant availability.

This is especially important for custom mixtures or those with long production times. 

Continuity plans

Some facilities establish continuity plans for essential mixtures, arranging duplicate supplies or standby cylinders.

Although such measures must be balanced against cost, they represent an effective risk mitigation strategy.

Perfecta: certified mixtures and operational support

Perfecta is the SIAD Group brand specialized in the production of high-reliability metrological gas mixtures.

With accredited facilities, qualified technical staff, and customized solutions, it supports laboratories and industrial plants in managing gas mixtures efficiently.

Create your custom mixture and consult our specialists for tailored advice on stability and supply solutions.