A Guide to Gas Flow Management Options

Environics specializes in custom systems, providing a number of options to customize your system in order to fulfill your specific requirements. The company encourages you to challenge them with your most difficult requirements.

Humidification Option

gas flow management

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The humidification option incorporates a continuous purge path to prevent moisture build-up and condensation. The humidification option is rear panel mounted and is made up of a humidifier and a 250 mL gravity feed D.I. water reservoir. The humidifier is made from a water vapor permeable tube made of Nafion (a Teflon derivative).

The humidifier is factory calibrated for a specific RH level to an accuracy of 5% (assuming a constant flow rate and gas temperature) and is NIST traceable. The humidification option allows specific Relative Humidity (RH) levels to be added to the output gas of the system. RH levels between 0 - 95% can be achieved.

Options Available

  • Variety of seal types depending on component gases
  • Temperature controlled water circulator
  • Adjustable humidity level
  • Simulate actual ambient R.H. level conditions in gas mixtures
  • Multiple flow rate calibrations

Canister Filling Option

gas flow management

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The Canister Filling option permits the gas mixing/dilution system to fill a canister to a certain pressure. The system will automatically stop when the desired pressure is attained, and even allows for the chosen pressure to be adjusted while filling. This option uses a mechanical pressure switch for most systems, which is adjusted to the chosen pressure.


  • Storage of low level multi-component mixtures from high level gases
  • Canister conditioning for VOC storage
  • Low level VOC storage

Purge Circuit Option

gas flow management

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Available in the S4000/4040/4020, the optional Purge circuit permits the user to send a purge gas through the entire system, or only a small portion of it, to flush any gas residue out of the mass flow controllers, solenoids, blend chamber, and tubing.

The Purge should be employed to flush dust and other particles out of a system which has not been used for a while, flush the system between the blending of gases which may be reactive, or clean the system after the use of gases which could present possible risks if left in the system because of corrosivity or toxicity. Frequent use of the Purge Mode will make the system safer, cleaner, and will prolong instrument life.

Silicon Coated Plumbing

gas flow management

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Silicon surface treatment of the gas path prevents surface adsorption of active compounds like ammonia, sulfurs, H2S, and mercury which are present on stainless steel surfaces. Also known as Silcosteel®/Sulfinert® or SilcoNert 1000/2000, coating the gas path also enhances efficiency, prolongs unit life and decreases moisture contamination.

A coating is typically employed in combination with a heated flow path and/or the purge circuit.

Common applications include:

  • Environmental testing
  • Wherever precise, reliable product sampling and transfer is needed
  • Refinery & petrochemical monitoring & control
  • Stack and flare sampling
  • Oil and gas downhole sampling

Heated Flow Path

gas flow management

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To prevent surface adhesion of gases within the gas path, a heated flow path is recommended. In addition to preventing adhesion, heating the gas path reduces contamination, improves response time, and prolongs unit life. A heated flow path is often used in combination with the purge circuit or silicon coating.

Permeation Oven/s

gas flow management

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There are many reasons to use permeation. Some use this option because the gases of interest are not available in cylinders. Others must utilize permeation to achieve low level concentrations. Lastly, the ease of obtaining and shipment permeation tubes is a huge benefit.

For the emission of the dry vapor form of the gas, this option enables the user to insert a disposable liquid gas permeable tube into a precision temperature controlled oven. The permeation oven can have a dedicated carrier gas flow controller, or that flow controller can be configured to use either the permeation oven, or a high pressure cylinder of gas; expanding the blending capabilities of the system.

Units can house a number of permeation ovens as required and each oven can hold multiple permeation tubes.


This information has been sourced, reviewed and adapted from materials provided by Environics, Inc.

For more information on this source, please visit Environics, Inc.


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