EATON Crouse Hinds MTL Measurements User Guide
- June 12, 2024
- EATON
Table of Contents
EATON Crouse Hinds MTL Measurements
Product Information
The MTL gas analysers & systems are designed for measuring and analyzing
cracked ammonia. These devices provide accurate measurements of the percentage
dissociation of ammonia based on thermal conductivity. The instruments are
available scaled in %Hydrogen, %Ammonia, or %Dissociation.
The MTL katharometer-based thermal conductivity analysers, specifically the
MTL Z1550 model, are recommended for making measurements of these mixtures.
These devices are stable and require calibration or verification every six
months. The measurements can be used in various industries, including the
metals industry.
Product Usage Instructions
To use the MTL gas analysers & systems for measuring cracked ammonia and obtaining accurate readings, please follow these instructions:
- Step 1: Ensure you have the MTL Z1550 model for this type of application.
- Step 2: Gather hydrogen and air, which are required for the procedure and easily obtained.
- Step 3: Connect the MTL gas analyser to a suitable power source.
- Step 4: Set the instrument to the desired measurement scale (%Hydrogen, %Ammonia, or %Dissociation) based on your requirements.
- Step 5: Prepare the cracked ammonia sample for measurement.
- Step 6: Introduce the cracked ammonia sample into the analyser following the manufacturer’s guidelines.
- Step 7: Allow the analyser to stabilize and display the measurement value.
- Step 8: Record the measurement value for further analysis or documentation.
- Step 9: Clean and maintain the MTL gas analyser according to the manufacturer’s instructions to ensure accurate and reliable measurements.
Note : It is recommended to refer to the MTL gas analyser user manual for detailed operating instructions specific to your model.
Measurements in Cracked Ammonia
When measuring the percentage dissociation of ammonia it is important to
understand what your instrument is reading, because definitions vary with the
industry in which the measurement is being carried out.
This note discusses the methods used and how to get the best level of accuracy
for your measurements.
When ammonia dissociates it does so according to the following chemical equation:
- 2NH3 = N2 + 3H2
For a partially dissociated situation (proportion x) it can be written:
- NH3 = 0.5 x N2 + 1.5 x H2 + (1-x) NH3
So hydrogen, ammonia and nitrogen will be present in precise proportions
depending on the degree of dissociation.
Hydrogen has a significantly different thermal conductivity to ammonia and
nitrogen, which means that a measurement of the mixture’s thermal conductivity
allows the amount of hydrogen and hence the amount of ammonia to be
calculated. The graph above shows this relationship.
Instruments are available scaled in %Hydrogen, %Ammonia or %Dissociation.
Definition of %Dissociation
- It can be seen from the equation above that when ammonia dissociates to form nitrogen and hydrogen, the volume of gas produced is greater than the original volume of ammonia. If 100 volumes of NH3 fully dissociates it produces 50 volumes of N2 and 150 volumes of H2.
- If only half the original volume of NH3 is dissociated and the other half remains unchanged, then the mixture produced comprises 50 volumes NH3, 25 volumes N2 and 75 volumes H2, a total of 150 volumes of which the ammonia is 1/3 or 33%. Because only half of the original ammonia has dissociated then in normal chemical terms it would be referred to as 50% dissociated.
- However, it is the practice in the metal treatment industry to calculate the ‘% of Dissociated Ammonia’ by measuring the percentage of ammonia remaining in the dissociated mixture and subtracting it from 100%.
- This approach does not take into account the volume change that takes place and in the above example this would give a result of 66.7%. When Eaton scales its instruments in ‘%
- Dissociation’ for this application it uses the ‘metals-industry’ definition and not the ‘true’ chemical one.
- The MTL katharometer based thermal conductivity analysers are ideal for making measurements of these mixtures. They are very stable devices, and six monthly calibration or verification periods are more than adequate. For this procedure only hydrogen and air are required, both of which are easily obtained.
Note : The MTL Z1550 model is used in this type of application
Eaton Electric Limited, Great Marlings, Butterfield, Luton Beds, LU2 8DL, UK.
Tel : + 44 (0)1582 435600 Fax: + 44 (0)1582 422283
www.mtl-inst.com
E-mail: mtlgas@eaton.com
© 2016 Eaton All Rights Reserved
Publication No. TN09 520-1008 Rev 3 191016 October 2016
EUROPE (EMEA): +44 (0)1582 723633
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The given data is only intended as a product description and should not be regarded as a legal warranty of properties or guarantee. In the interest of further technical developments, we reserve the right to make design changes.
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