ULTRAMAT 6E — Infrared (NDIR) Analyser, Rack Version

ULTRAMAT 6E is a rack version of an infrared analyser for integration into a measuring assembly. The public range in this category includes, for example, 7MB2121-0CA00-1AA1 and 7MB2121-1CA00-1AA1. When choosing, first link the measured component to the specific configuration. It cannot be inferred from the series name that any device will measure a different gas merely by changing the unit in the menu.

Why two optical paths are compared

ULTRAMAT 6 compares the infrared absorption of the measuring and reference branches. The signal is evaluated by a gas-filled two-layer detector; the design is explained in the Siemens ULTRAMAT 6 / OXYMAT 6 manual.

The absorption bands of different gases can overlap. The Siemens guide describes increasing selectivity with optical coupling elements and optional filters. In the specification, mainly state the admixtures that change in the process, for example water vapour. A stable result for one calibration mixture is not in itself verification of all combinations of process components.

Rack and sample conditioning as one project

When mounting, respect the support and access spaces according to the manual.

Draw the gas lines behind the device in the switchboard design. Pulling out for service must not depend on a random hose length. Determine in advance which joints will be disconnected during replacement and how the measuring path will subsequently be checked.

Design sample conditioning according to the required inlet conditions. Siemens AP 11 for sample preparation lists coolers, filters and liquid breakthrough monitoring. These elements perform different tasks: attach their diagram and the method of evaluating operating states to the project. When comparing results, always agree on whether you refer the concentration to wet or dry gas.

Author's example: the correct number on the wrong range

Consider a model linear 4–20 mA signal. When a range of 0–10 vol. % is assigned, a current of 12 mA corresponds to half the span: (12 − 4) / (20 − 4) = 0.5,, i.e. 5 vol. %. If the device switched to a model range of 0–20 vol. %, the same current of 12 mA would mean 10 vol. %. A control system left on the original conversion would still display 5 vol. %.

The ranges stated are the author's assumptions, not specifications of the MLFBs offered. The example does not describe incorrect measurement by the optical section, but incorrect interpretation of the transmitted signal. If the project uses range switching, the acceptance test must include information about the active range and the subsequent conversion. For a fixed range, verify that a service change cannot unnoticeably decouple it from the control system settings.

For acceptance of the model transmission, prepare a table of common test points and results at both ends of the chain. Each row must indicate the range currently used. Agreement at a single current point alone does not distinguish a correct conversion from a random intersection of two incorrectly set characteristics.

How to verify the entire measuring function

Write down a test from sampling to archiving of values. In one step, verify the concentration of a known mixture; in the next, the agreement of the analyser display with the reading in the control system. Separately check units, the decimal place and the meaning of the operating state. Record the switching time and the return after calibration together with the result.

For service, it is useful to keep not only the analyser settings but also the version of the conversion in the higher-level system. A common mistake is to readjust the sensitivity of the device when only the units or range on the other side of the interface differ. The correction can then mask the original problem and worsen a previously correct local measurement.

FAQ

Can oxygen be added simply by configuring the IR channel?

This cannot be assumed. Separate oxygen measurement is offered, for example, by OXYMAT 61; any combined assembly must actually be fitted with the appropriate measurement.

What if the analyser is to be close to the process?

Compare ULTRAMAT 6F in field version. The decision should include the sampling route and service accessibility, not just free space in the switchboard.