- Temperature and flow rate controlled automatically
- Touchscreen setup and operation
- Temperature control with an accuracy of ±0.01°C up to 110°C
- PPB to high PPM range
- Multiple calibration modes
- CE-certified
The Model 345 contains two mass flow controlled (MFC) systems – the carrier system and the dilution system. The carrier gas system is typically a fixed flow which passes through the permeation chamber containing the permeation device. The temperature of the chamber, which controls the permeation rate of the calibration gas from the permeation device, is tightly regulated to provide both accurate and precise results. The chamber temperature is adjusted from 30°C (or 2°C above ambient, whichever is higher) to 110°C. The carrier stream mixes with the calibration gas in the chamber and is then fed forward to the mixing tee.
In standard models (below) the dilution gas stream is controlled and measured by the diluent MFC, and feeds forward to the other side of the mixing tee. The mixture of the carrier and the diluents is then fed to the distribution tee, which allows the flow to move to the Span Out and the Overflow bulkhead connectors for distribution.
The Model 345 has one valve to direct the carrier flow. In the Span position, the dilution stream and carrier streams pass through the mixing tee, facilitating a choice of calibration modes.
