Looking for information on flow switches
Thread Content
I urgently need some information on flow switches, the kind used for measuring fluids in large-diameter pipes. If anyone has such information, please share it with me; thanks in advance
The SHLK series of thermal flow switches introduced by Shanghai Hongke Automation Instrument Co., Ltd. are based on the thermal principle. The enclosed probe contains two resistors: one of them is heated and serves as the sensing resistor, while the other remains unheated and functions as the reference resistor. As the medium flows, the heat from the heated resistor is carried away, causing a change in its resistance value. The difference between the values of these two resistors is used as a basis for determining the flow rate. The SHLK series of thermal flow switches feature a compact design, no moving parts, low maintenance requirements, and easy installation. One model can meet various pipe diameter requirements, the switch signal can be adjusted continuously, and there is extremely low pressure loss. Options include high-temperature, high-pressure, explosion-proof, and dual-contact (upper and lower limit alarm) types of flow switches. The SHLK series of thermal flow switches are designed for use with both gases and liquids; they can be applied in pneumatic and hydraulic systems. They are suitable for monitoring the interruption of flow in gases, flare gas, circulating water, heating systems, cutting fluids, and lubricants, as well as for providing protection against pump idling. □ Key Technical Specifications
Item: Standard Type, High-Temperature Type, High-Pressure Type, Simple Type
Appearance:
Medium temperature range: -40～80℃, -40～280℃, -40～80℃, -40～80℃
Nominal pressure: ≤5MPa, ≤5MPa, ≤25MPa, ≤10 MPa
Fixing method: G20 pipe thread, G20 pipe welding, G20 pipe welding, G20 pipe thread
Explosion protection rating: ExdIIBT6, ExdIIBT6, ExdIIBT6, —
Response time: ≤5s, ≤9s, ≤9s, ≤5s
Stabilization time after power-on: ≤3 minutes
Flow rate: Gas: 0～30m/s; Liquid: 0～5m/s
Power supply: DC24V/100mA. Contact capacity: AC220V/1A, DC24V/2.5A
Protection rating: IP65
Connection cable: RVV4×1.0
Connection distance: 1500m
Environmental requirements:
Ambient temperature: -40～65℃; Relative humidity: 5%～95%; Atmospheric pressure: 86～106KPa
□ Installation instructions
﹡ It can be installed on horizontal, vertical, or inclined pipelines. The length of the straight pipe section should be at least 3D upstream and 2D downstream. (D is the nominal diameter of the pipe) ﹡ For pipes with a diameter of ≥DN150, the length of the fixed splice G20 can be chosen to be 2–3 cm; one end is welded to the pipe, while the other end is used to fix the flow switch. For pipelines ≤DN150, the length of the fixed short-circuit G20 should be increased to position the sensor of the flow switch as close as possible to the center of the pipeline. ﹡ Use a wrench to rotate the stainless steel hexahedron during installation; under no circumstances apply force to the aluminum casing. After debugging, tighten the upper cover and lock the locking screw of the upper cover. ﹡ Four-wire wiring method, where 24V is connected to the positive power supply terminal, 0V to the negative power supply terminal; CON is an open-contact output, while COFF is a closed-contact output. □ Alarm point adjustment ﹡ Precise adjustment: If you want to use a certain flow rate as the alarm point, after ensuring that the flow switch is functioning properly, allow the flow rate corresponding to the set point to pass through the pipeline. Measure the voltage V0 between OMT and TP1 using a voltmeter, and then adjust potentiometer W1 so that the voltage between OMT and TP2 equals V0. ﹡ Fuzzy adjustment: When there is no gas flow in the detection pipeline, turn potentiometer W1 counterclockwise until the relay indicator light FG1 lights up; then turn the potentiometer W1 half a turn in the opposite direction. At this point, the gas flow rate inside the pipeline is approximately 0.5 m/s, and the gas flow rate in the pipeline can be calculated based on the pipe diameter.
Item: Standard Type, High-Temperature Type, High-Pressure Type, Simple Type
Appearance:
Medium temperature range: -40～80℃, -40～280℃, -40～80℃, -40～80℃
Nominal pressure: ≤5MPa, ≤5MPa, ≤25MPa, ≤10 MPa
Fixing method: G20 pipe thread, G20 pipe welding, G20 pipe welding, G20 pipe thread
Explosion protection rating: ExdIIBT6, ExdIIBT6, ExdIIBT6, —
Response time: ≤5s, ≤9s, ≤9s, ≤5s
Stabilization time after power-on: ≤3 minutes
Flow rate: Gas: 0～30m/s; Liquid: 0～5m/s
Power supply: DC24V/100mA. Contact capacity: AC220V/1A, DC24V/2.5A
Protection rating: IP65
Connection cable: RVV4×1.0
Connection distance: 1500m
Environmental requirements:
Ambient temperature: -40～65℃; Relative humidity: 5%～95%; Atmospheric pressure: 86～106KPa
□ Installation instructions
﹡ It can be installed on horizontal, vertical, or inclined pipelines. The length of the straight pipe section should be at least 3D upstream and 2D downstream. (D is the nominal diameter of the pipe) ﹡ For pipes with a diameter of ≥DN150, the length of the fixed splice G20 can be chosen to be 2–3 cm; one end is welded to the pipe, while the other end is used to fix the flow switch. For pipelines ≤DN150, the length of the fixed short-circuit G20 should be increased to position the sensor of the flow switch as close as possible to the center of the pipeline. ﹡ Use a wrench to rotate the stainless steel hexahedron during installation; under no circumstances apply force to the aluminum casing. After debugging, tighten the upper cover and lock the locking screw of the upper cover. ﹡ Four-wire wiring method, where 24V is connected to the positive power supply terminal, 0V to the negative power supply terminal; CON is an open-contact output, while COFF is a closed-contact output. □ Alarm point adjustment ﹡ Precise adjustment: If you want to use a certain flow rate as the alarm point, after ensuring that the flow switch is functioning properly, allow the flow rate corresponding to the set point to pass through the pipeline. Measure the voltage V0 between OMT and TP1 using a voltmeter, and then adjust potentiometer W1 so that the voltage between OMT and TP2 equals V0. ﹡ Fuzzy adjustment: When there is no gas flow in the detection pipeline, turn potentiometer W1 counterclockwise until the relay indicator light FG1 lights up; then turn the potentiometer W1 half a turn in the opposite direction. At this point, the gas flow rate inside the pipeline is approximately 0.5 m/s, and the gas flow rate in the pipeline can be calculated based on the pipe diameter.