Series 4000 Multi-Component Gas Mixing System Built to Handle Explosive Gases

The Environics^® Series 4000 is a multi-component gas mixing system that comes with a sophisticated Windows user interface. The units are built to suit the specific requirements of users and can be integrated with extra features such as Silconert/Sulfinert coating, cleaning for oxygen service, and speciality seals (metal, Kalrex). In addition, custom systems can be designed to handle explosive gases, should this application be necessary.

The multi-component gas mixing system automatically mixes up to three separate gases in a balance gas. The mixture of gases can be used to generate precise gas calibration standards, producing gaseous atmospheres or creating gas mixes for production or analytical research purposes. The multi-component gas mixing system can create gas concentrations from percent to ppb levels for both single and multi-point calibration.

Two components are included in the system — the Series 4000 instrument and the user's personal computer. The user interface is a Microsoft^® Windows application that communicates with the Environics system through a USB or RS232 serial interface.

The Series 4000 contains a single chassis supporting up to four mass flow controllers (MFCs). The MFCs are factory calibrated using a primary flow standard traceable to the United States National Institute of Standards and Technology (NIST). In order to increase accuracy and reduce flow controller nonlinearity, all flow controllers utilize an 11 point calibration table with linear interpolation.

Dual Chassis Design

The explosion proof version of the Series 4000 includes a dual chassis design, which isolates the electronics from the gas plumbing. The electronics enclosure includes the power supply and PC boards for controlling the Mass Flow Controllers (MFC) and direct acting solenoid valves in the second enclosure.

The electronics enclosure connects to a computer via a 9 pin serial port connector and cable. The 4040 software, on the computer, communicates with the microcomputer board inside the electronics enclosure.The second enclosure is sealed and houses the MFCs, valves and components to support the enclosure purge. A continuous purge flows through the enclosure while it is running. This serves two purposes. The first is to carry out heat built up by the internal components. The second is to dilute any potential leaks that may develop. The gas plumbing inside this enclosure was vacuum leak tested to 1 x 10⁸ atm cc / seconds He.

Image Credit: Environics

Further to the to continuous purge flow, the enclosure is pressurized to approximately 5 inch H₂O while running the enclosure purge. This provides and indicator that the purge is activated as well as preventing any air leaks into the enclosure from outside. A safety vent was added to vent the enclosure to atmosphere if the pressure inside the enclosure reaches 20 inch H₂O. This could happen if, for some reason, the purge vent becomes blocked or the pressure on the purge rotameter is too high. The two enclosures are connected electrically via two control cables labeled "MFCs" and "VALVES". An earth ground wire is connected from the electronics chassis to the aluminum mounting plate inside the purged enclosure. This safely discharges any static electricity that can build up in a system with flow.

Product Features and Benefits

The key features and benefits of the Series 4000 multi-component gas mixing system are as follows:

Enables multi-point calibration of analyzers

Simultaneously mixes up to three gases in a balance gas at user-defined concentrations

Internally-stored mass flow controller calibration tables

Modular design enables additional gas circuits to be added

Automatic calculation of dilution and span gas flows

User definable cylinder library facilitates easy selection of regularly used gas cylinders. Each cylinder may include many component gases, with automatic K-factor calculation.

Instrument Operation

The Series 4000 includes three basic modes of operation:

Concentration Mode – This mode enables users to produce a blend by entering target gas concentrations for each source gas cylinder, and the required total output flow for the mix.

Flow Mode - This mode enables users to specify the flow rate of each gas cylinder.

Program/Schedule Modes – This mode makes it possible to program the instrument for unattended operation. In addition, programs can be recalled and run in any sequence, at different times or dates.