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Special-Sensors for Automation Flow Sensors

Flow Sensors Contents Technique and application for flow sensors Technique and application for flow sensors, amplifiers and compact models . . . . . . . . . . . . 1.03 - 1.07 Terminology / Setting instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.08 - 1.09 Technique and application for flow sensors inline-digital display . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.10 Ex area certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.11...

Flow Sensors Technique and application Function The function of the flow controller is based on the thermodynamic principle. The sensor is heated internally a few degrees °C compared to the medium into which it projects. When the medium flows, the heat generated in the sensor is conducted away by the medium, i. e. the sensor cools down. The temperature within the sensor is measured and compared to the temperature of the medium. The state of flow can be derived for each medium by the temperature difference attained. – In metal processing, e.g. rolling mills and wire drawing machines, the...

Dimensions of the gasket Thread 3 = Chamber 4 = Edge 5 = Counterpart The temperature-sensitive measuring elements are fitted in the tip of the probe. The probe tip and the adjoining thread/mounting part are made in one piece of stainless steel in many probes. This guarantees absolute tightness and high compressive strength. Special materials are used in corrosive, and particularly in oxidizing media, since stainless steel shows only limited resistance to corrosion in this application. In standard applications, probes can be mounted independently of the direction of flow of the medium. In...

Flow Sensors Technique and application NPT threads NPT threads can be provided as an alternative for all types which have a G1/2 or a G3/4 thread. NPT threads are conical and must be screwed into an equally conical counter-part. Two types of NPT threads must be distinguished. NPT thread according to ANSI B 1.20.1 does not ensure a good seal by itself and requires the use of a sealing medium, e.g. Teflon tape. It is not possible to use flat gaskets with this type of thread. Inline sensors are inserted directly into the line of a pipe. This design does not feature any measuring pins...

Flow SensorsTechnique and application Special materials Hastelloy B-2 (2.4617) belongs to the group of highly corrosion-resistant nickel-molybdenum alloys. This material has excellent characteristics in reducing media, e.g. in hydrochloric acid of any concentration and for a large range of temperatures. It can also be used in hydrochloric, sulphuric, acetic and phosphoric acid media. Good resistance against corrosion such as pitting, crevice corrosion, chlorine induced stress, corrosion cracking, hair-line corrosion, abrasion and corrosion within the heat influence zone allows for a large...

Flow Sensors Technique and application Amplifiers All amplifiers have a multicolour LED display which visually indicates the flow tendency. If the LED light is red, the preinstalled limit value is not reached and the switching output is not activated. The yellow LED indicates that the limit value was reached and the output is active. In addition to the yellow LED, 4 more green LEDs can light up to indicate how much the limit value is exceeded. For the installation of the amplifiers, make sure that the devices are not subject to heat build-up. The distance between adjacent devices should not...

Flow Sensors Technique and application • Terminology Detection range The detection range of a probe or compact device indicates the flow velocities of the medium for which the probe can provide an analysable signal. If the medium is not specified, the details for water are applied. Because the different media have different thermal conductivity, the detection range as well as the temperature drift are also dependent of the respective medium. At the upper and lower limit of the detection range, the temperature drift is higher. The detection range does not limit the maximum flow rate a sensor...

Switching output General • The output is active when the yellow LED is lit. • Set the switching point with the potentiometer at the front of the device. • Keep the flow rate and medium temperature stable during adjustment and wait for the temperature to equalise between the sensor and the medium. • The flow rate must be within the detection rate of the measuring probe. • If present, remove the protective screw M3 x 4 from the potentiometer opening for the duration of configuration. Monitoring a flow limit for being exceeded • Specify the flow rate or stop the flow and wait for the standby...

Flow Sensors Technique and application • Inline-Flow monitoring Flow monitoring and measuring Signal filter The EGE-inline flow controllers with digital display monitor flow rates in the range of 0,05...100 l/min and display the flow rate digitally. They feature front panel buttons used to call functions and modify settings. The application area includes all areas of flow monitoring and measuring, in which a flow display is desired. The parameter for the signal filter allows inputting a value that determines the time interval in which the measuring signal is averaged. Inputs between 0 to 8...

Flow SensorsTechnique and application •Use in hazardous areas Ex marking [A] [B] The EX measurement probes of the 400 meet the basic requirements of Directive 94/9/EC. Electrical boundary data, permissible temperature ranges as well as installation and connection instructions are specified in the operating instructions of EX equipment. Zone classification and categories The frequency and duration of the occurrence of a hazardous atmosphere determines the zone classification. Zone 0 / Category 1 (Gas) Zone 0 is an area in which a potentially explosive atmosphere in the form of a...