Host Device Transmitters for Interchangeable Sensors

Indigo 200 Series Transmitters accommodate an array of
smart sensors.
Image courtesy Vaisala

Our previous post was about Vaisala's new interchangeable humidity sensors in their Indigo line. The Indigo sensors, and other smart probes, are designed to work with the Indigo series transmitters to provide top flight performance in process measurement and control applications.

Transmitters enable plug-and-play setup with the smart sensors. Output options include analog, relay and Modbus. The browser based wireless interface allows configuration and viewing access to the transmitter. The LCD color display enables easy viewing on location.

Share your process measurement challenges with process instrumentation experts, leveraging your own process knowledge and experience with their product application expertise to develop the best solution.

Indigo 200 Series Transmitters from Alliance Technical Sales, Inc.

Heated Impulse Lines on Pressure Gauges and Transmitters

Successive cutaway view of self-regulating heat trace

cable showing various layers of material

Courtesy BriskHeat

Temperature of the environment surrounding process equipment and instruments can sometimes have a deleterious impact on its function. A common example is cold weather impact on the impulse lines connecting pressure gauges or transmitters to process piping in outdoor or unheated locations. While the process lines may be large, with sufficient mass flow and insulation to prevent freezing, this may not be the case for small diameter impulse lines. Liquid freezing in cold weather conditions can be a threat to process operation, depending on the type of liquid being used. A safeguard exists for impulse lines where the lines can be traced with a heat source, allowing for counteraction of the environmental conditions and maintenance of proper operation.

There are a number of ways to deliver heat to an impulse line. Recognize two essential goals, with the first being to prevent freezing or other changes to the fluid in the line that would impact the response or accuracy of the instrument reading. The second goal is related to the heat tracing itself. The delivered heat must not be great enough to impact the fluid in the impulse line and generate a false pressure reading. Optimally, delivering heat in a fashion that is limited to what is necessary to maintain the impulse line fluid in an ideal working state is best.

One example of heat tracing an impulse line is through the placement of a tube or small diameter pipe, located in close proximity to line, through which low pressure steam flows. Insulation is applied to the bundle and the steam line serves as a heat source. The tube transfers heat to the impulse line when steam flows. After the steam heats the impulse line, a steam trap accompanying the system collects condensate for return to the boiler. It is also conceivable that the steam line could ultimately vent to atmosphere, with no condensate return. There are a number of concerns that must be addressed in the design of the steam portion of this scenario, since it would be necessary to keep any condensate from freezing under all anticipated operating conditions, including process shutdown.

A second common solution for freeze protection of impulse lines is through the installation of electric heat tracing. Two-wire cable serves as protection against the cold. When powered, the heat from the cable keeps the line warm. Electric heat tracing is available in a broad range of physical configurations, including cables, tape, blankets, and other flexible and solid shapes. Control of the electric heat system can be accomplished with an external controller and sensor, or a self-regulating heat trace cable can be used. As with a steam heating system, there are some specific considerations for electric heat tracing. Thermal insulation is still considered a best practice. Electric power must be delivered to the installation, and a means of monitoring heat trace performance for faults or failure should be included in the design.

Share your heat tracing requirements and challenges for process piping and other industrial applications with a product specialist. There are many options and product variants from which to choose. A consultation can help direct you to the best solution.

New M300 Series Single and Multi-Variable Transmitters From Mettler Toledo

Mettler Toledo recently introduced a new line of transmitters to deliver maximum effectiveness from their array of water quality and process analytics sensors. The M300 is available in 1/2 DIN and 1/4 DIN sizes, with a single or dual channel configuration. Two versions are tailored for process analytics applications or water quality applications. Analog or digital ISM sensors for pH/ORP, conductivity, dissolved oxygen and ozone can be utilized with the new transmitter, which features intuitive operation and excellent ergonomics.

Learn more about the M300 transmitter and see it in action in the video. Reach out to a product specialist with your water and process analytical challenges, combining your process knowledge with their product application expertise to develop effective solutions.

Transformer Monitoring for Hydrogen, Moisture, and Temperature

Specialized transmitter for monitoring moisture,
hydrogen, and temperature levels in electrical
transformers. (Vaisala)

Electrical transformers are an intricate part of the power transmission and distribution system. Many transformers are insulated with mineral oil that also facilitates heat transfer for unit cooling. Abnormal thermal and electrical stresses, such as local overheating and electrical discharge ocurring in the transformer, cause decomposition of insulating oil and papers, resulting in production of a range of gases, one of which is hydrogen.

Routine dissolved gas analysis, or DGA, is performed on oil filled transformers to provide a measure of unit health. The process involves the extraction of an oil sample from the transformer, which is then subjected to laboratory analysis. The process is manual, time consuming, and only performed infrequently. It is known that the presence or increasing levels of certain gases is an indicator of internal faults or general wear and tear in a transformer. A reliable stream of data can provide value as a predictive indicator of overall transformer health and maintenance requirements. The endgame is to prevent unit failure and the resultant shutdown of connected customer equipment.

General recommendations call for trend monitoring of hydrogen. The rate of change in the concentration can be more indicative than the overall level in some cases. Any rapid change is a harbinger of potential problems. Adopting a proactive approach, based on transformer oil condition, can extend transformer useful life.

Moisture content of transformer oil is another concern. The presence of water boosts oil and paper insulation deterioration. Water presence in transformers generally has two potential sources, atmospheric and internal. The sources of moisture in the oil are not a subject of this article, but water reduces the dielectric strength of insulating oil and can facilitate corrosion or other material degradation within the transformer case.

Internal temperature is an indicator of the current operating condition of a transformer and is useful in evaluating its performance.

All three of the parameters mentioned, moisture, hydrogen, and temperature, are continuously measured by the new MHT-410 from Vaisala. The transmitter provides three isolated loop powered 4-20 mA outputs that provide the user with continuous data on moisture content, hydrogen concentration, and oil temperature. The compact unit installs easily in less than 30 minutes to provide online monitoring of insulating oil without any need for pumps, membranes, or sampling.

The new MHT410 provides real time transformer health monitoring, as well as information on transformer fault situations. You can find out more with a review of the data sheet included below. Reach out to a product specialist with your measurement challenges.

Moisture, Hydrogen, and Temperature Measurement in Electrical Transformers from Alliance Technical Sales, Inc.

Humidity and Temperature Transmitters for Demanding Humidity Measurement

HMT330 Series Humidity and Temperature Transmitters
Courtesy Vaisala

Humidity, the amount of water vapor in the atmosphere or a gas, can be an important measurable attribute of an industrial process. Many are aware of the measurement of relative humidity in HVAC applications and its impact on human comfort in occupied spaces, but the measurement of water vapor in air can be a required measuring point in many other processes that pose far greater challenge.

In addition to common wall or duct mounting applications, where the instrument is easily inserted or placed into the environment to be measured, there are applications that call for special adaptations to the instrument or sensing probe.

• High pressure
• Vacuum
• High temperature
• High humidity
• Pressurized pipelines
• Presence of chemical contaminants

Meeting the full range of industrial process control operations requires stable measurements and the choice of multiple configurations and options to customize the instrument to the process demands. Here are some features worth considering.

• Multiple variants to match the basic process requirement
• Full 0 to 100% humidity measurement range up to +180°C (+356°F)
• PT 100 RTD for accurate temperature measurement
• Pressure tolerance up to 100 bar
• Superior sensor accuracy and stability
• Graphic display and keypad for local operation
• Multilingual user interface
• Good chemical tolerance
• Corrosion resistant housing
• Delivered with multi-point NIST traceable calibration certificate
• Analog outputs, RS232/485, WLAN/LAN
• MODBUS protocol support (RTU/TCP)
• Long term manufacturer warranty

While not all processes may require, or benefit from, the inclusion of all the listed features and capabilities, reviewing what is available and considering which features may provide better operability in your process can be beneficial. I have included a data sheet below that illustrates the HMT330 Series of humidity and temperature transmitters from Vaisala. Share your humidity measurement challenges with a product specialist. Combining your process knowledge with their product application expertise will produce solid solutions.

Vaisala HMT330 Series IndustrialTemperature and Humidity Transmitters from Alliance Technical Sales, Inc.