Bartec Benke designs and manufactures analytical instruments for gases and liquids in the petrochemical industry. In order to track product quality during the manufacturing process and also to conform to product specifications, for products such as diesel, paraffin, kerosene, benzene, heating oil, Naphtha and hydrocarbons, measuring solutions are utilized to ascertain the boiling point, flash point, cloud point, vapour pressure and solidification.
In order to ensure precise analysis, there must be continuous flow of samples into the analysers. Standard flow volumes for these types of applications are in the range of 2 to 40l/h. The products may have high viscosity rates of up to 40 cSt (centistokes) and have little or no electric conductivity. Bartec Benke often employs variable area flowmeters for sample processing systems, process analysers and turnkey analszer cabinets.
KROHNE’s DK 32 variable area flowmeters were used to determine the continuous flow of sample. These systems do not require any power supply. By means of the local display and the built-in needle valve, the preferred flow rate can be directly set through the DK 32 measuring instruments. To detect blockages and leaks in the sample line, reduced flow monitoring using limit switches is carried out for continuous process analysers. Figure 1 shows the cloud point analyser.
Figure 1. Cloud point analyser
The variable area flow measuring principle is applied for the actual sample flows of 2…40l/h, and as well as for instrument air (800…1400 Nl/h), inert gas (0.5…5 Nl/h), and cooling water (20…60l/h).
The flowmeter functions on the float measuring principle. The measuring segment includes a metal cone, wherein a float can easily move up and down. The medium flows via the flowmeter from bottom to top. The float is capable of modifying itself so that the form drag W, its weight G, and the buoyancy force A acting on it are in perfect equilibrium: G = A + W.
Figure 2. Operating principle
In case of the DK32, DK34 and DK37/M8M devices (Figure 2, left image), the flow-dependent height of the float in the measuring segment is relayed through a magnetic coupling and shown on a scale. For the DK37/M8E (Figure 2, right image), the flow-dependent height of the float in the measuring segment is relayed to the electronic display through a magnetic coupling on sensors S1 and S2.
KROHNE’s DK 32 low-flow measuring instruments provide a low-cost alternative and are capable of measuring with adequate precision at a maximum permissible error of 4% of the calculated value. However, more than the precision, the consistency and repeatability of the flow are important.
The built-in needle valve saves time on planning and deploying extra valves. Given that the measuring principle can be employed for both gases and liquids, the same kind of device is utilized for both the auxiliary fluids and the sample flows. This not only improves familiarity with the measuring instruments, but also streamlines operation. Also, electric power supply and inlet and outlet runs are not required, making it easy to install and integrate the systems.
The DK 32 measuring device is approved for use in adverse environments according to IECEx, ATEX, NEPSI and FM standards. This means, the devices can be utilized in analyser equipment.
Benefits of DK 32 Variable Area Flowmeter
KROHNE’s DK 32 variable area flowmeter (Figure 3) offers the following benefits:
- Measurement of viscous products sans electric conductivity
- Consistent measurement and dosing of low flows of gaseous and liquid products
- Local measured value display sans power supply
- Space-saving installation without inlet and outlet runs
- Optional limit switches for monitoring
- Certification for hazardous areas in accordance with IECEx, ATEX, NEPSI and FM standards
Figure 3. DK 32 variable area flowmeter
KROHNE offers a wide range of variable area flowmeters that can be effectively used for detecting leaks and blockages in process analysers in the petrochemical industry. These devices, with built-in needle valves, allow accurate dosing of sample flow and simplify the entire installation and integration process
About KROHNE Messtechnik GmbH
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This information has been sourced, reviewed and adapted from materials provided by KROHNE Messtechnik GmbH.
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