Customised solutions available

The author: Manfred Diers Sales Director, Labom

Measuring pressure is one of the most common applications for instruments in process technology, yet only rarely is one process exactly like another. This means that customised solutions are often superior to off-the-shelf products when it comes to accuracy and safety. On the other hand, they usually cost more money and require more time to develop. Labom’s Pascal CV is a novel system that comprises pressure transmitters for a wide range of applications, all sharing a common basic design. This new series is the outcome of decades of experience in designing customer-specific solutions with highly standardised components and processes. As a result, models in stock can be shipped in just a few days. The delivery time is a maximum of two weeks within Germany for the standard types in the Pascal CV series or four for special versions. This ability to supply promptly is invaluable for production line manufacturers and operators aiming to equip, and in particular retrofit, processes with a large number of pressure measuring points.

All the devices in Pascal CV series measure the relative and absolute pressures of gases, vapours and liquids with an accuracy equal to 0. 15 % of the span and repeatability equivalent to 0.05 % of the nominal range. Even with 5:1 turndown, 0.15 % accuracy can still be achieved. The temperature error is ±0.15 %/ 10 K in relation to the nominal range at temperatures from 0 to 60 °C.

Pascal CV pressure transmitters provide a 4 to 20 mA output signal and can optionally be integrated in a complex digital process controller using the Hart protocol (Version 6) or Profibus PA. Connections to a fieldbus or downstream equipment are a simple matter. Labom offers the 4 to 20 mA module and a Profibus PA mod-ule as the basic configuration. The other function modules include the Hart module, a display module with a multifunctional, five-digit display and bar graph and a switching module with two potential-free channels. The latter module is rated for up to 0.5 A of alternating current, is electrically isolated in all directions and operates without an additional power source. These “plug and measure” standard components can be screwed onto the housing of the measuring device on site in just a few minutes without interrupting the production process and are immediately ready for operation without recalibrating. The housing is designed to optimise the volume, so that “breathing” as a result of changing ambient temperatures is virtually eliminated. In addition, the individual function modules and the sensor chamber are completely sealed. The IP66 enclosure ensures a high degree of protection against moisture.

The electronic modules and measuring cell are continuously self-monitoring for maximum process safety. With its easy-to-replace function modules and a large number of standard-compliant and manufacturer-specific process connections, the Pascal CV concept is particularly flexible and custom configurable.

An acceptance inspection certificate for the material and a calibration certificate according to DIN EN 10204-3.1 are available for all of the Pascal CV series. Each Pascal CV model can also be supplied with Atex-compliant Ex protection for gases and dusts.

The option of placing large orders for basic modules and then customising them by installing compatible function modules has economic advantages, especially for plants that require numerous different pressure transmitters. A manufacturer of ultra-filtration systems for protein production in the pharmaceutical sector, for instance, was able to use two transmitters with a display and one with a switching output from the Pascal CV hygiene series in each of its plants. The design, material and surface qualities of the instruments conform to the recommendations of EHEDG, FDA and GMP. The available hygienic process connections include DIN 11851, DIN 11864-1, clamp, Varivent, Hygienic Tubus and DRD as well as G1A connections with hygienic, elastomer-free seals.

It is so easy to combine several of these hygienic pressure transmitters using the Profibus PA protocol that “smart applications” beyond pressure measurement are also possible. A beverage manufacturer uses differential pressure measurements with two Labom transmitters at different points on a storage tank to determine the quantity of concentrate that is transferred to the production process as precisely as possible. This measurement is of vital importance because the financial success of a beverage producer depends on secret recipes for the basic concentrate.

The series for standard and hygienic applications are offered for measuring ranges from 0 to 80 mbar up to 0 to 400 bar and can be used at maximum temperatures from 90 to 160 °C, depending on the model. Labom has developed a line specifically for the chemical and petrochemical industries. These transmitters measure pressure ranges between 0 to 80 mbar and 0 to 400 bar at process temperatures as high as 400 °C. All parts in direct contact with the medium are available in stainless steel, tantalum, Hastelloy, a PTFE coating or other special materials. Together with Labom diaphragm seals in a flange-type design, the transmitters can be combined in a modular system for use in aggressive, highly viscous, crystalline or adhesive media. The explosion-protected Pascal CV is also a popular choice for monitoring pressure in many chemical and petrochemical applications, for example in electrolysers that produce hydrogen from water or in gas control equipment for propane extraction.

cpp-net.com/0312424

In a Combibar system, a diaphragm seal connects an electrical pressure transmitter to a mechanical pressure gauge so that both gauges measure the same point in the process. Even if a power failure occurs, the process pressure can still be read off on the indicator of the mechanical pressure gauge. Labom has now realised a Combibar system for pressure vessels in a brewery comprised of the ultra-compact Pascal CV and a Varivent process connection. Together with the Pascal CV self-monitoring system, this Combibar solution provides twice the normal level of process safety. If the electrical power supply fails, the self-monitoring system detects a signal dropout and an integrated switching module automatically triggers a pre-configured response to a pressure drop. This space-saving and eco-nomical system assures immediate TÜV certification for any new plant.