Bypass Mass Flow Controller (MFC) for gases

Transcription

1 Bypass Mass Flow Controller (MFC) for gases Bypass MFC with Capillary technology for nominal flow rates from ml N /min to l N /min Suitable for aggressive gases Fieldbus option Type 870 can be combined with... Type 0 Multi-channel programme controller Type 00 / or /- way valve Type 60 /-way valve Type 870 is a unit for the control of the mass flow of gases that is relevant for most applications in Process Technology. The measured value provided by the sensor (see the description on page ) will be compared in the digital regulation electronics with the predefined set point according to the signal; if a control difference is present, the control value output to the proportional valve will be modified using a PI-control algorithm. In this way, the mass flow can be maintained at a fixed value or a predefined profile can be followed, regardless of pressure variations or other changes in the system. Type 870 can optionally be calibrated for two different gases, the user is able to switch between these two gases. MFC Configuration software The control element, a proportional valve working at low friction guarantees a high sensitivity and a good control characteristics of the unit. Typical application areas are gas dosing or rather the production of gas mixtures in: Process technology Environmental technology Surface treatment Material coating Fuel cell technology Technical data Full scale ranges ) (Q nom ) Operating media to 000 ml N /min N equivalent neutral, non-contaminated gases, other gases on request Max. operating pressure (inlet pressure) 0 bar ( psi) depending on the orifi ce of the valve Calibration medium operating gas or air with conversion factor Medium temperature -0 to +70 C Ambient temperature -0 to +0 C Accuracy ±.% of Rdg. ±0.% F.S. (after 0 min. warm up time) Linearity ±% F.S. Repeatability ±0.% F.S. Control range :0 Settling time (t 9% ) < s Body material aluminium or stainless steel.0 Electr. housing material PBT Sealing material FKM, EPDM, others on request Port connections NPT /, G /, screw-in fi tting or sub-base, others on request Control valve (proportional valve) valve is closed when power is off valve orifi ce kvs-value 0.0 to.0 mm to 0.09 Electr. connection ) at standard conditions.0 bar (a) and 0ºC -pin sub-d plug -pin M plug (only with DeviceNet) -pin M socket code B (only with Profi bus-dp) Power supply V DC Voltage tolerance ±0 % Residual ripple < % Power consumption max. 6. W, max. 9 W () Set point Feed impedance 0- V, 0-0 V, 0-0 ma or -0 ma > 0 kω (voltage), Output signal Max. current, volt. output Max. load, current output Fieldbus communication Protection class < 00 Ω (current) 0- V, 0-0 V, 0-0 ma or -0 ma 0 ma 600 Ω Profi bus-dp or DeviceNet IP0 Dimensions [mm] (without fi tting) 07 x. x 8 mm Total weight ca. 00 g (aluminium body) Mounting position horizontal or vertical Light emitting diode display indication for Power, Limit/Communication, (default, other allocations possible) Error Binary input two (default, other functions possible). start autotune Binary output (default, other functions possible) Certification (see operating instructions). not assigned one relay-output for. setpoint not reached max. load: V, A, VA various environmental testing, electromagnetic compatibility p. /

2 Schematic diagram of bypass measurement Measurement is based on the bypass principle. A laminar flow element in the main channel generates a small pressure drop. This drives a small flow proportional to the main flow through the actual sensor tube. sensor tube Two heater resistors, which are connected in measuring bridge, are wound on this narrow stainless steel tube. In the zero-flow state, the bridge is balanced, but with finite flow, heat is transported in the flow direction and the bridge becomes unbalanced. gas flow prefilter The dynamics of the measurement are determined by the tube walls, which act as a thermal barrier. They are hence significantly poorer, on principle, than with sensors having resistor placed directly in the medium flow. Through use of suitable software in the controller, correction times are obtained that are adequate for a large part of the applications (in the range of a few seconds). With contaminated media, we recommend installing filter elements upstream. This avoids changes in the division ratio between main flow and sensor tube, as well as changes in the head transmission chaused by deposits on the walls. With these sensors, even aggressive gases can be controlled, since all essential parts in contact with the medium are fabricated in stainless steel. With this sensor prinziple it is also possible to convert between different gases. A choice of some gases are listed in the table below, others on request. Gas Faktor f N.00 Air.00 O 0.99 H.0 Ar. He. CO 0.76 Q(gas) = f x Q (N). By using the gas factors it is possible that the accuracy is not within the datasheet specification. For applications which need high accuracy it is recommended to calibrate under application conditions. Notes regarding the selection of the unit For the proper choice of the actuator orifice within the MFC, not only the required maximum flow rate Q nom, but also the pressure values directly before and after the MFC (p, p ) at this flow rate Q nom should be known. In general, these pressures are not the same as the overall inlet and outlet pressures of the whole plant, because usually there are additional flow resistors (tubing, additional shut-off valves, nozzles etc.) present both before and after the controller. Please use the request for quotation form on p. to indicate the pressures directly before and after the MFC. If these should be un-known or not accessible to a measurement, estimates are to be made by taking into account the approximate pressure drops over the flow resistors before and after the MFC, respectively, at a flow rate of Q nom. In addition, please quote the maximum inlet pressure p max to be encountered. This data is needed to make sure the actuator is able to provide a close-tight function within all the specified modes of operation. The request for quotation form on page contains the relevant fluid specification. Please use in this way the experience of Bürkert engineers already in the design phase and provide us with a copy of the request containing the data of your application together with your inquiry or order. Ordering table for accessories (connectors are not included on the delivery) Article Item no. -pin electrical connection Sub-D socket -pin solder connection 98 7 Sub-D hood for Sub-D Buchse, with screw locking Sub-D socket -pin with m cable, ass. on one side Sub-D socket-pin with 0m cable, ass. on one side Adapter Adapter RS - for connection to a PC 6 78 PC cable for RS 9-pin socket/plug m Adapter RS8 6 8 Communication software MassFlowCommunicator Info at p. /

3 Dimensions [mm] Standard version x M - 6 depth A A Port size A: G/ or NPT /. Sub-base version 0 M 8. ø6 ø M. 07 p. /

4 PIN Belegung pole Sub-D plug Relay output - NC contact Relay output - NO contact Relay output - C contact GND -V-supply and binary inputs V supply V output (For factory use only!) 7 Setpoint input GND 8 Setpoint input + 9 Process value output GND 0 Process value output + DGND (for RS) Binary input Binary input RS RxD (without driver) RS TxD (without driver) Only with fieldbus Profibus DP socket B-encoded M (DPV max. Mbaud) VDD RxD / TxD - N (A-line) DGND RxD / TxD - P (B-line) Shield DeviceNet plug M Shield VDD DGND CAN_H CAN_L p. /

5 MFC/MFM applications - request for quotation Please fill out and send to your nearest Bürkert sales centre* together with your inquiry or order Company Contact person Customer No. Department Address Tel./Fax Postcode/Town Note You can fill out the fields directly in the PDF file before printing out the form. MFC-application MFM-application Quantity Required delivery date Medium data Type of gas (or gas proportion in mixtures) Density [kg/m ] ) Medium temperature [ºC or ºF] Moisture content [g/m ] Abrasive components / solid particles Fluidic data no ºC ºF yes as follows Maximum flow Q nom l N cm N m N /h ) cm s /min (sccm) ) kg/h l s /min (slpm) ) Minimum flow Q nom l N cm N m N /h ) cm s /min (sccm) ) kg/h l s /min (slpm) ) Inlet pressure at Q nom Outlet pressure at Q nom Max. inlet pressure p max p p Pipe run (external-ø) metric, mm imperial, inch MFC/MFM- port connection without screw-in fi tting / thread G-thread (DIN ISO 8/) / thread NPT-thread (ANSI >B.) with screw-in fi tting sub-base version Ambient temperature Material data ºC Body material Sealing material Electrical data Output/input signal Aluminium Stainless steel FKM EPDM Other 0-0 ma/0-0 ma -0 ma/-0 ma 0-0 V/0-0 V 0- V/0- V Profi bus DP DeviceNet Please quote all pressure values as overpressures with respect to atmospheric pressure [barg] ) ) at:.0 bar (a) and 0ºC at:.0 bar (a) and 0ºC To find your nearest Bürkert facility, click on the orange box In case of special application conditions, please consult for advice. We reserve the right to make technical changes without notice. 070/0_EU-en_ p. /