Innovative Adapter Allows Easy, Less Costly Upgrade of Level Transmitter

An installed view of the Model 706 Adapter.

Magnetrol International, a global leader in level and flow measurement instrumentation, has introduced an innovative product that allows for the retrofit and upgrade to a higher level transmitter package for existing guided wave radar (GWR) level probe applications.

The new Eclipse Model 706 GWR Adapter allows users to keep existing Eclipse 705 GWR probes in place, and upgrade to the Eclipse 706 transmitter and its advanced electronics and DTM.

The ECLIPSE 705 guided wave radar transmitter, with its patented easy-access, angled enclosure has gained wide popularity and has a huge installed base around the world.

The Eclipse 706 transmitter supports both the FDT/DTM and enhanced DD standards. A DTM (Device Type Manager), similar to device drivers used in computers, provides a user-friendly graphical interface to make device configuration, maintenance, diagnostics and troubleshooting a breeze. The DTM allows viewing of valuable configuration and diagnostic information such as the echo curve in tools such as PACTware™, AMS Device Manager, and various HART® Field Communicators. 

In many cases, GWRs are installed in hard to access areas, where removing the sensing probe from
the tank or vessel is prohibitive. Additionally, or the integral electronics and cumbersome DTM of older Eclipse Model 705s is less comprehensive and less user-friendly than the newer Model 706s. 

The Model 706 Adapter allows existing Model 705 probes to be retrofitted with the Model 706 transmitter without breaking the process seal, gaining the best-in-class GWR performance that comes along with the Model 706 including the highest Signal-to-Noise (SNR) ratio in the market.  High SNR is particularly helpful in low dielectric liquids often found in refineries.

Aside from the increased performance, the technician could now use the latest Model 706 DTM for troubleshooting.  The main DTM features emphasized by users are:

• The capability, on a single screen, to view not only the echo curve itself but also the operational conditions of the transmitter along with the configurable parameters.  You can then change parameters and refresh the curve to see immediate results without going into multiple screens.
• Data logging capabilities where you can capture all of the data associated with the last nine events, which include configuration parameters, echo curve, echo curve history and event history.
• The Model 706 has the capability to monitor build-up as a percent of level threshold or as a rate.  Meaning the user can potentially track the build-up percentage or rate through a HART variable to trigger a flushing process or for timely maintenance / cleaning intervals.

Benefits of the Eclipse® Model 706 GWR Adapter:

• Backwards compatibility with existing Eclipses probes.
• Extends the lifecycle of existing Model 705 probes.
• The added benefit of facilitating the upgrade without opening up the process.
• Lower cost because you are only replacing the transmitter and not the probe.
• Compact design adds 3.15” of installation height.
• Customers get all the features of the Model 706 Transmitter while using their existing Model 705 probes.
• Adapters are in stock at Magnetrol

For more information, contact M.S. Jacobs and Associates. Call them at 800-348-0089 or visit their web site at https://msjacobs.com.

The Ashcroft Ordering Handbook

Ashcroft, Inc. manufactures a wide variety of electronic and mechanical pressure and temperature instruments are produced in this facility under the brand names of Ashcroft^®, Heise^®and Weksler^®. Ashcroft products are recognized as best-in-class for pressure and temperature measurement, including gauges, thermometers, switches, transducers, transmitters, instrument isolators and diaphragm seals and control and calibration equipment.

The Product Ordering Handbook includes descriptions, part numbers, and specifications for all Ashcroft products.

Download the Ashcroft Ordering Handbook from the M.S. Jacobs web site here.

Hydrostatic Pressure Measurement for Determining Liquid Level

Pressure transmitters can be used to provide liquid level in
pressurized or open vessels.
Photo courtesy Azbil North America

Pressure measurement is an inferential way to determine the height of a column of liquid in a vessel in process control. The vertical height of the fluid is directly proportional to the pressure at the bottom of the column, meaning the amount of pressure at the bottom of the column, due to gravity, relies on a constant to indicate a measurement. Regardless of whether the vessel is shaped like a funnel, a tube, a rectangle, or a concave polygon, the relationship between the height of the column and the accumulated fluid pressure is constant. Weight density depends on the liquid being measured, but the same method is used to determine the pressure. 

A common method for measuring hydrostatic pressure is a simple gauge. The gauge is installed at the bottom of a vessel containing a column of liquid and returns a measurement in force per unit area units, such as PSI. Gauges can also be calibrated to return measurement in units representing the height of liquid since the linear relationship between the liquid height and the pressure. The particular density of a liquid allows for a calculation of specific gravity, which expresses how dense the liquid is when compared to water. Calculating the level or depth of a column of milk in a food and beverage industry storage vessel requires the hydrostatic pressure and the density of the milk. With these values, along with some constants, the depth of the liquid can be calculated.

The liquid depth measurement can be combined with known dimensions of the holding vessel to calculate the volume of liquid in the container. One measurement is made and combined with a host of constants to determine liquid volume. The density of the liquid must be constant in order for this method to be effective. Density variation would render the hydrostatic pressure measurement unreliable, so the method is best applied to operations where the liquid density is known and constant.

Interestingly, changes in liquid density will have no effect on measurement of liquid mass as opposed to volume as long as the area of the vessel being used to store the liquid remains constant. If a liquid inside a vessel that’s partially full were to experience a temperature increase, resulting in an expansion of volume with correspondingly lower density, the transmitter will be able to still calculate the exact mass of the liquid since the increase in the physical amount of liquid is proportional to a decrease in the liquid’s density. The intersecting relationships between the process variables in hydrostatic pressure measurement demonstrate both the flexibility of process instrumentation and how consistently reliable measurements depend on a number of process related factors. 

Share your process measurement and instrumentation requirements and challenges with professionals that specialize in their proper selection and application. Combining your own process knowledge and experience with their product application expertise will help to develop effective solutions.

Level Measurement: Comparing Displacer Transmitters and Differential Pressure Transmitters

Electronic Displacer Transmitter
Courtesy Magnetrol

Liquid level measurement is ubiquitous throughout industrial fluid processing operations. Whether via direct or inferential means, the fluid level data point is an integral part of operational and safety plans for an installation.

Magnetrol, a globally recognized leader in the design and manufacture of level measurement instrumentation, has produced a comparison of displacer transmitters and differential pressure transmitters applied to liquid level measurement.

What is a displacer transmitter?

Displacer transmitters are considered a direct means of level measurement.

Quoted from Magnetrol website page on displacer transmitters...

Electronic displacer level transmitter technology operates by detecting changes in buoyancy force caused by liquid level change. These forces act upon the spring supported displacer causing vertical motion of the core within a linear variable differential transformer.
As the core position changes with liquid level, voltages are induced across the secondary windings of the LVDT. These signals are processed in the electronic circuitry and used to control the current in the 4-20 mA current loop. The enclosing tube acts as a static isolation barrier between the LVDT and the process media.

 How does a differential pressure transmitter measure liquid level?

Liquid level can be inferred through the measure of the pressure generated by the column of liquid in a tank or vessel. The measurement device must be calibrated for the specific gravity of the measured media in order to attain reasonably accurate results. There are a number of installation arrangements of differential pressure transmitters that will accommodate tanks open to atmosphere, closed pressurized tanks, and more.

The comparison is included below and provides some interesting points to consider. Share your level measurement application challenges with a product application specialist. Combining your process experience and knowledge with their product application expertise will produce the best solutions for your process measurement needs.

Comparing Level Measurement Methods: Displacment Transmitter vs Differential Pressure Transmitter from MSJacobs-Cali