The 4600A Dynamic Diluter

The analysis of Volatile Organic Compounds at ppm through sub ppb levels requires the generation of standards for instrument calibration. These standards can be prepared in passivated stainless steel canisters or Tedlar™ bags followed by transfer onto sorbent tubes if necessary depending on the application to be calibrated.

The most accurate procedure for obtaining ppb level standards is to dilute an NIST referenced standard mixture contained in cylinders at low ppm levels.

Accuracy can be maximized if the transfer is done under equilibrium conditions so initial losses on surfaces will not affect overall final concentrations. The only way to achieve this equilibrium is by performing dynamic dilutions.

The 4600A Dynamic Diluter

prepares analytical standards in canisters or Tedlar™ bags by blending 1-5 cylinders together with a diluent gas under mass flow control. The flow stream first passes through a blending region to insure complete homogeneity before sampling into the canister or bag. The diluter can be given several minutes to reach equilibrium under the current temperatures, pressures and flows before the stream is partially diverted into the storage receptacle. The remainder is vented out of a 35psig back pressure regulator which maintains a constant pressure in the manifold whether or not canister filling is occurring. Obtaining the required concentration at the outlet is done by setting up the method in the Windows™ user interface and then down-loading to the 4600A through the SmartLabII™ control network.

The 4600A comes equipped with 2 mass flow controllers, one for diluent flow control (5000 sccm) and a second for a single standard cylinder (50 sccm). Additional flow controllers can be ordered for channels 3-6 which will increase the number of cylinders being blended to 5. All MFC's have Kel-F seals to reduce impurities introduced into the flow path. The extra channels can be ordered with MFCs ranging from 10 to 1000 sccm.

Multi-Canister Automation

An option is available for preparing multiple canisters at one or several concentrations while operating unattended. This has many advantages over single canister standard preparation. Most importantly, canister filling can be done more consistently because the human element has been removed. A predefined method is followed which sets the flow rates for each channel, allows the system to equilibrate for the same period of time,then fills the canister to a consistent pressure. Records for flow rates, equilibration time, fill time, initial pressure, and final pressure are maintained for later review. Completely automated operation makes it easier to generate fresh standards on a more frequent basis.

Autocalibration

Prepare standards on or off-line. The 4600A can operate in two different modes. For laboratories wishing to prepare standards in canisters off-line for later use in system calibration, canisters can be attached directly to the 4600A and filled to 35 psia with the desired concentration of standard. Alternatively, the 4600A can be linked directly to the 7100A preconcentrator and can be turned off and on as needed to calibrate the preconcentrator. The later method is particularly helpful when analyzing reactive compounds where long term storage in canisters is suspect. Also, direct attachment eliminates the need for dedicating canisters for standards and can help to reduce laboratory clutter.

SmartLabII™ Control Interface

The 4600A is controlled using the Entech SmartLabII control network which can control an entire air analysis laboratory from a single computer operating under Microsoft™ Windows™. The interface includes screens for defining and running methods and for setting up sequence tables for multi-canister operation. Methods allow control of channel flow rates, while sequence tables designate fill parameters such as equilibration times, channel number, and required final pressure (or fill time for bags).The graphical interface simplifies operation and accelerates the user's understanding of operation principles.

Position 4 mass flow meter mounting kit

4600-044

Position 5 mass flow meter mounting kit

4600-045

Position 6 mass flow meter mounting kit

4600-046

Choose the additional mass flow meters for your application

10 sccm Flow Controller

03-10010

50 sccm Flow Controller

03-10050

100 sccm Flow Controller

03-10100

200 sccm Flow Controller

03-10200

500 sccm Flow Controller

03-10500

1000 sccm Flow Controller

03-11000

5000 sccm Flow Controller

03-11500