ULTRAMAT 6F — Infrared (NDIR) Analyser, Field Version

ULTRAMAT 6F makes it possible to place infrared measurement in a field installation. This public category offers 7MB2111-1AB00-1AA1. The choice of location should take into account sample accessibility, service and the environment around the enclosure. The field version still works with a supplied sample; its location at the process does not replace the design of gas sampling and conditioning.

The same absorption physics, different installation conditions

Infrared radiation is absorbed by the measured gas; ULTRAMAT 6 compares the measuring and reference branches. Overlapping absorption bands cause interference. The field enclosure separates the analytical section from the electronics; see the Siemens ULTRAMAT 6 / OXYMAT 6 manual.

For the order, determine the sample composition including fluctuating admixtures. Describe water vapour and states after shutdown separately. Data on the resistance of the enclosure to the environment cannot decide whether unconditioned wet or contaminated gas can be supplied to the measuring chamber. The conditions of the specific version must match the conditions of the entire sampling route.

Sample conditioning and location of service points

The manual requires the exclusion of condensation in the sample. The outlet pressure must also be assessed; the discharge is not automatically pressureless.

For the assembly drawing, prepare the connections of the inlet, service branches and outlet. For each joint, mark who supplies it and who verifies its execution. The interface between two suppliers must be described as carefully as the analyser itself.

Depending on the task, include filtration, cooling, condensate drainage and liquid monitoring. The function of these elements is shown by Siemens AP 11 catalogue. In the assembly design, leave access to points of regular inspection. A service technician should recognise the sample inlet, calibration branch and outlet without dismantling adjacent equipment.

Author's example: the coldest point decides

For our own heat balance, let us choose a sample with a dew point of 12 °C at the pressure considered. The designer expects, as a model, 24, 18 and 30 °C in the individual sections of the route. The smallest difference from the dew point is 18 − 12 = 6 °C. If the middle section cooled to 8 °C after a shutdown, the difference would be 8 − 12 = −4 °C.

Assuming unchanged pressure and composition, this section thus falls below the dew point. A higher temperature elsewhere on the route does not remove the problem of this cold point. All numbers are the author's assumptions, not temperature limits of ULTRAMAT 6F, the value of its heating or the reserve recommended by the manufacturer.

The model serves to compile a checklist, not to size heating. It does not include the temperature distribution inside the connections, actual heat transfer or changes in dew point with changes in pressure. Therefore draw the transitions between individual sections in the project and determine how their condition will be verified before the sample is supplied. The average temperature of the whole route alone does not replace this check.

Location selection and common mistakes

Compare two or three real mounting locations. For each, record the length of the route, space for operation, the possibility of gas discharge and access during shutdown. Add an assessment of the ambient conditions according to the documentation of the selected unit to the shortest route. Neither proximity to a hot pipe nor easy mechanical mounting in itself confirms the suitability of the location.

Also plan an operational test after interruption of sampling and restart. Check whether a valid result can be distinguished from stabilisation. A common mistake is to increase the flow for speed without checking the permitted conditions. Another is to call the entire installation heated on the basis of only one heated part; the project must also address transitions and connections.

FAQ

Does the letter F automatically mean an ATEX version?

No. The field design designation is not a certificate for a specific MLFB. Approvals, conditions of use and any additional equipment are verified individually.

When does a central switchboard make sense?

If the sampling and service concept correspond to it, compare ULTRAMAT 6E. Other measuring principles are offered in the overview Siemens gas analysers.