Perma Pure
PD Series – High-Flow Gas Dryers for Demanding Applications
When high gas flow rates and effective moisture removal must go hand in hand, the Perma Pure PD Series provides a robust and proven solution. These polytube gas dryers are designed for applications where standard single-tube dryers are not sufficient – delivering high drying capacity while preserving gas composition.
With flow rates up to 40 lpm, the PD Series is ideal for continuous processes, emissions monitoring, and industrial gas analysis.
Multiple Nafion™ tubes deliver maximum drying capacity at high flow rates
Unlike single-tube dryers, the PD Series uses bundles of multiple Nafion™ tubes housed in a single shell. This design dramatically increases the available membrane surface area, allowing significantly higher gas flows without compromising drying performance.
Water vapor is selectively transferred through the Nafion membrane, while other gas components remain in the sample stream. The result is efficient moisture removal even in high-flow applications where precision still matters.
Purge-assisted drying for stable and controllable performance
The PD Series operates using a dry purge gas flowing countercurrent to the sample gas on the outside of the Nafion tubes. As long as the purge gas has a lower water vapor partial pressure than the sample gas, moisture is continuously drawn out of the sample.
This purge-assisted design provides:
- Stable and repeatable drying performance
- Flexibility to adapt to different moisture loads
- Reliable operation in continuous-duty systems
Instrument air or nitrogen is typically used as purge gas, flowing at two to three times the sample flow rate.
Engineered for industrial environments and continuous operation
PD Series dryers are designed for long-term, high-demand use. Multiple housing and fitting material options are available, allowing the dryer to be tailored to corrosive gases, elevated temperatures, or harsh industrial environments.
With no moving parts and self-regenerating membrane technology, the PD Series offers high reliability and minimal maintenance – even in 24/7 operation.
Key features that support high-performance gas analysis
- High flow capacity – up to 40 lpm depending on model
- Selective removal of water vapor only
- Multiple Nafion™ tubes for maximum drying efficiency
- Purge-assisted design for stable and controllable performance
- Wide choice of housing materials including polypropylene, fluorocarbon, and stainless steel
- Suitable for continuous operation in industrial systems
- Compatible with gas-to-gas humidification, when required
Well suited for continuous processes and emission monitoring
The PD Series is commonly used in:
- Continuous Emission Monitoring Systems (CEMS)
- Process gas analysis with high sample flow
- Environmental monitoring stations
- Sample conditioning downstream of gas coolers
- Industrial and petrochemical process monitoring
Practical benefits for your system and your data quality
By integrating a PD Series dryer into your system, you gain:
- Stable moisture control at high flow rates
- Improved analyzer protection against condensation
- More reliable measurement results over time
- Reduced maintenance and downtime
- Flexible system design, thanks to multiple size and material options
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