Keywords: Valve Position Indicator DeviceNet Intelligent Valve Position Indicator Introduction The control system monitors and controls devices (on-off valves or regulating valves, etc.) via the fieldbus. It makes the field bus control system not only can realize the simulation quantity control, but also can realize the switch quantity control, the application scope greatly expands. Depending on the scope of use, StoneL products are available in a wide range of degrees of protection and communication protocols: AS-i (actuator sensor interface) protocol, Modbus protocol, DeviceNet protocol, Foundation Fieldbus protocol. In addition, The gateway enables communication with Profibus or Ethernet and other protocols. StoneL valve position indicator is divided into 6 series, respectively, Eclipse, Visual Indicator, Quartz, SolaR, Onxy, Hawkeye. The compact, all-in-one Eclipse is compatible with ISO-compliant Namur actuators; the independent Visual Indicator clearly visualizes the position of the valve over 75 feet; the epoxy-coated Quartz Ideal for explosion-proof / fireproof environments; corrosion-resistant and water-resistant SolaR products are ideal for general-purpose applications in process applications; fully aerodynamic Onxy is ideal for corrosive and / or flame retardant environments; fully sealed 316 The all-in-one Hawkeye stainless steel housing and thermoplastic polycarbonate test probe are designed for use in a flame-retardant environment. For petrochemicals, StoneL introduced the FF bus valve position indicator, this valve position indicator optional matching low-power explosion-proof solenoid valve. Solenoid valve current consumption of , low voltage and low current start, explosion-proof grade Eexia IIC T6. This greatly increases the number of valve position indicators available on the bus. Up to 16 valve position indicators on one bus save wiring. Changzhou Chemical Plant polyvinyl chloride (PVC) Silo control system uses 28 DeviceNet protocol intelligent valve position indicator (SolaR series), the system controller uses OMRON C200HG, communication master station C200HW-DRM21-V1 will be 28 Valve communication terminal hanging in a 4-wire trunk network to achieve the remote monitoring and control of the valve. Second DeviceNet Bus Function DeviceNet can connect up to 63 devices to a network of trunk line network, which can be directly connected with the ordinary PLC, including the more popular domestic AB, GE, OMRON and other companies PLC products. DeviceNet allows you to directly add simple digital and complex analog devices, two-wire power supply and two-wire with data to form a 4-wire bus. DeviceNet networks have been designed and validated to prove their suitability for use in hazardous situations such as anti-braking, air blowing bags and more. At the same time it can be very good to eliminate noise, suitable for industrial use, such as industrial process environment. General Purpose with DeviceNet Protocol (SolaR Series) The function of the intelligent valve position indicator is described below. Structure: Two digital inputs (valve position on and off). Two digital outputs with 24V DC (control solenoid valve). A two-wire analog input (8-bit resolution) can be directly with two-wire 4 ~ 20mA meter. Communication baud rate: the software chooses 125k, 250k or 500k. Wiring diagram shown in Figure 1. Three Changzhou Chemical Plant PVC Silo Control System Introduction 1. Process and control instructions Process shown in Figure 2. TK-1-1, TK-1-2 two silos for storage of 1 # PVC device of PVC finished powder; TK-3-1, TK-3-2 two silos for storing PVC No. 3 PVC device powder material. PVC powder by two sets of devices, respectively, weighing the weighing tank of the unit by the compressed air will be transported out of the powder. UV-6, UV-13, UV-20 and UV-27, respectively, as feed valves for TK-1-1, TK-1-2, TK-3-1 and TK- UV-21 and UV-28 are the discharge valves of TK-1-1, TK-1-2, TK-3-1 and TK- 3, UV-4, UV-5 TK-1-1 bunker air blowing mixing valve and sub-valve; UV-8, UV-9, UV-10, UV-11, UV- -2 blower air mixture main valve and sub-valve; UV-15, UV-16, UV-17, UV-18, UV-19 TK- UV-23, UV-24, UV-25, UV-26 for TK-3-2 blower air mixture master and sub-valve. PT-1 for the blower pressure transmitter, PV-1 silo blowing pressure control valve. Feed Control: TK-1-1, TK-1-2 silos as a group, TK-3-1, TK-3-2 silos as a group. Take the TK-1-1 and TK-1-2 silos as an example: After the program starts, a feed valve (system default UV-6) is automatically opened, and the silo feed valve is set to manual, automatic and on / off , A group of silo feed valve can not be opened at the same time, if the artificial mistakenly open the second feed valve, the system alarm, but not implemented. The program first determine whether the material level is normal. If the measured value is lower than the lower limit of 5% (3.2mA) and higher than the range of 105% (20.8mA) that is level meter error, malfunction alarm. When the material level gauge is normal, the feed hopper's material level is greater than the set value LL (when the feed valve is closed, the blowing process is not performed), start the blow mixing process of the silo, and open the blower valve (TK -1-1 blower main valve is UV-1, circulation blower valve is UV-2, UV-3, UV-4, UV-5) At this point the total valve open, four branches per cycle Tset minute hair until the bunker reaches a high set value LH after the closing of the silo feed valve (UV-6), open the other feed valve (UV -13) feed; full of material silos (TK-1-1) After blowing fully Tset hour mixing valve automatically stop the hair blowing action. Discharge control: the flow screen discharge valve only manual switch valve button, four silos can only open a discharge valve, if the artificial mistakenly open the second discharge valve, the system alarm, but not implemented. When the silo level below the lower limit LLA or the remaining amount W1 is less than the set value WLA, and then the silo discharge valve is open, the alarm and prompt change warehouse packaging, bag replacement or replacement batch number. Air valve can be programmed and controlled. Program control: as described above. Manned: Each group only set the start and stop, at the beginning, the group opens the main valve, sub-valve automatically Tset cycle; stop, then close all valves. Air pressure PID control: set the pressure alarm. PID parameter adjustment, the role of direction changes, manual, automatic button, set value settings; MV settings; screen: the total process view, sub-flow chart, material level trend curve, the trend of the pressure curve, parameter list settings. 2. Control System Hardware Introduction Control system uses OMRON C200HG PLC, man-machine interface with OMRON NT631 touch screen. Using a 16-point digital input module C200H-ID212 a 16-point digital output module C200H-OC225 a 8-channel analog input module C200H-AD003 a two-loop PID control module C200H-PID03 a DeviceNet protocol network master C200H-DRM21-V1 one. System components shown in Figure 3. Four application results As a result of DeviceNet bus technology, from a cost-effective point of view, than the traditional point-to-point valve position indicator to save 30 to 40% of the construction and installation and hardware configuration costs. This project saves a total of 70000RMB of laying cable 800m, cable threading pipe 500m, cable threading box 50 and other construction materials, including construction and installation of labor costs; PLC hardware configuration saves 16 points of switch input Card 4, 16 points switch output card two, an expansion box, accounting for 10,800 yuan. The above two items saved a total of 80,800 yuan and saved 40%. At the same time, the construction volume was greatly reduced, the construction time was reduced, and precious time was won for driving the new factory. From the scene a few months of use of the situation, safe and reliable work, maintenance is almost reduced to zero, reaching a satisfactory result for the smooth operation of the factory to create a certain degree of economic benefits.
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