Doubling up: How dual seals can protect sensitive pharma processes (Part 2)

Sometimes, pharmaceutical processors select a more specialised arrangement for a mechanical seal for additional security. Mounting two mechanical seals, such as the Type 1 and Type 2 elastomer bellows seals or the Type 4615 general-purpose single-cartridge metal bellows seal, in a tandem arrangement within the seal chamber can improve safety, increase longevity and reduce maintenance requirements in pharmaceutical applications. In tandem arrangements, each seal has a distinct function: 

Mechanical seals that support pressurised processing 

John Crane mechanical seals combine hydraulic and spring force to keep the rotating face and a stationary seat pressed together. Similarly, dual pressurised seals utilise a barrier fluid (often regulated by API plans) to maintain pressure and support mixer and reactor performance by:  

Agitator seals for sterile processing 

John Crane single mixer seals support sterile, high-purity production. These solutions include the Type 32, which has an optional debris well for easy flushing and sterilisation during CIP and SIP cycles and the ATEX-compliant Type 32D. Both incorporate dry-running faces to prevent barrier fluid contamination of the barrier fluid 

The hygienic design of the Type 5280/5281/5282 meets Qualified Hygienic Design (QHD) and GMP standards for full cleanability and SIP cycles. 

The CK series of vessel and agitator seals supports steel, glass-lined and alloy vessel designs and can be configured for top-entry mixers, dryers or filters. They are compatible with high-viscosity media, solids-laden batches and potent compounds.  

The Type CK 728 is available in liquid-lubricated (W), gas-lubricated (G), dry-running (D) or a unique gas/dry face combination (GD) format. Both are ATEX-compliant for explosive environments.  

Meanwhile, changing the seal faces on the Type CK-725 and Type CK-726 vessel and mixer seals will convert from the liquid lubricated version to a contacting dry-running seal (Type CK 725D and Type CK 726D), and both offer particle-free performance during sterilisation.  

Designed for steel-made agitated chemical reaction vessels to DIN 28136, both can switch between wet and dry operation and offer debris well and cooling flange options.  

Support systems: Underpinning mechanical seal integrity in pharmaceutical cycles 

Any process is only as strong as its weakest spot, and when materials and cleaning cycles are run at high pressures and temperatures, in always-on environments, it makes sense to stabilise and protect pressurised seals.   

Seal support systems such as John Crane’s GR1 ensure stable barrier gas or fluid environments for agitator seals. Similarly, the GR‑2 and GR-3 stainless steel reservoirs provide buffer/barrier fluid to a dual-seal arrangement. 

In the same way, maintaining equipment health by underpinning systems with reliability support can optimise pharmaceutical cycle performance. Many elements of the John Crane Performance PlusTM modular service framework can augment operators’ uptime by maximising scheduled downtime to meet maintenance schedules. 

Reliability services: Supporting process integrity by minimising downtime 

The Reliability Support Programme is a dedicated service contract that can extend the life of mechanical seals and rotating equipment by addressing recurring failures and providing targeted support for wet seals without the need for a full-time on-site engineer. It is the preferred option for those looking for expert support to improve reliability while managing day-to-day operations internally. 

Condition monitoring: Preventing contamination through early detection 

Minimising production downtime is easier when process owners can predict, with data-driven accuracy, the problem and the need for intervention. The vibration, thermography, ultrasound, fluid analysis, performance testing, Motion Amplification® and fugitive emissions detection tools in our Asset Condition Management segment help pharmaceutical companies align downtime with maintenance schedules.  

Bringing it all together: A contamination-proof sealing strategy 

Pharmaceutical processes involve many moving parts, and no single solution can support uptime, maximise productivity and minimise downtime. Instead, companies find that combining solutions and support can support processing success and maintain an operational advantage.  

Similarly, predictive monitoring using digital technologies such as John Crane Sense® provides full visibility of crucial assets, to prevent unplanned stoppages and maximise the benefit of scheduled maintenance downtime.  

Finally, these technologies can be supported, maintained and optimised by John Crane’s global service network to deliver long-term reliability in the most critical pharmaceutical sealing applications. 

For the pharmaceutical industry, integrating the right technology, monitoring and technical support into an integrated sealing strategy can dramatically reduce contamination risk and support GMP compliance. 

How John Crane helps support product purity 

We can help address the unique and challenging requirements of the pharmaceutical industry with products to meet industry safety and reliability standards, as well as local environmental regulations, to help customers increase their uptime. 

In addition to a century of sealing expertise, John Crane offers pharmaceutical-specific sterile solutions which enable customers to operate safely in sterile environments.  

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