Cutting Costs with the Series 3000 Gas Mixing / Gas Delivery System

The Environics^® Series 3000 gas delivery/blending system is used to achieve on-site gas blending of 100% pure bulk gases. It provides an alternative solution to using costly premixed cylinders of gas. In contrast to premixed cylinders, the Environics model 3000 offers a repeatable blend of gases, employing precision thermal mass flow controllers. The system can address particular market and process requirements in a flexible manner. Although two and three gas mixtures are typically used, gas mixtures involving more constituents can also be produced. The main benefits of the system are cost-savings by using pure gases instead of premixed cylinders, and the repeatability of the mixture. The system pays for itself due to these savings.

The system is primarily controlled by Human Machine Interface (HMI); color touch screen and PLC are combined. A number of I/O modules are connected to all the electro-mechanical devices. Ethernet connection is a standard feature on all S3000 systems. A free software utility is also provided, allowing remote monitoring and operating of the instrument over an Ethernet connection. Optional features include alarms, remote operation, an oxygen-compatible construction, and a gas humidifier.

For the purposes of blending, the flow rate of each gas is controlled by precision mass flow controllers (MFCs). All MFCs are calibrated at 11 points on a primary flow standard traceable to NIST. The software of the S3000 uses the 11 points of calibration data, and applies linear interpolation in order to provide a more linear and accurate flow rate, thus resulting in a precision blend of gases.

Precision mass flow meters (MFM) are available as options, and can be installed on the outputs of the MFCs. These electronic meters are designed to monitor the flow rate of each flow controller. Based on the metered flows, the PLC mathematically determines the actual blend concentration, thus offering an independent check on the MFC performance. All MFMs are also calibrated at 11 points by applying linear interpolation.

The system is manufactured in a NEMA 4 wall mount enclosure. Internal electrically grounded aluminum panels are provided for support, and a clear polycarbonate door protects the controls. Optional enclosures are also available. Tube and tube fitting connections are made in 316 grade stainless steel.

During active mixing, the instrument transfers the diluted gas mixture through an in-line static mixer in order to ensure a homogenous mix of gases. A controllable positive pressure is allowed so as to satisfy the requirements of a process downstream. The mixer provides gas to a ballast tank, and can be turned off and on when the pressure increases and decreases in the tank. This can prove to be useful when there is a need for conserving gas in situations of sporadic demand or intermittent usage.

An optional audible and/or visual alarm can be fixed on the top of the instrument to alert operators about specific fault conditions. An alarm would be triggered if the interpreted concentration from the optional flow meters is beyond a user-adjustable tolerance. An added new feature is that the alarms can be emailed to keep the operators updated even when they are not present in the site. This is possible, if the IP address of the email sever has a static IP address. Environics can be contacted for more information on this new feature.

Product Features and Benefits

Optional precision MFMs can be installed on the outputs of the MFCs

Combined color touch screen and PLC. The new Unitronics article featuring the Gas Mixing and Delivery System can be referred for knowing more about this feature.

Flow standard accuracy up to 1% of reading

Optional audible and/or visual alarm, email alarms

Repeatability up to +/- 0.05% of full-scale

Applications

Modified Atmospheric Packaging

Gas Processing and Blanketing

Welding Shielding Gases

Controlled Atmospheric Storage

Semiconductor fabrication