A low-temperature circulation pump is a device that uses a mechanical refrigeration system to cool a heat transfer medium (such as ethanol, ethylene glycol aqueous solution, or silicone oil) to a set temperature, and achieves precise temperature control through circulating transportation. Widely used in fields such as chemical reactor cooling, biological sample preservation, and low-temperature material testing. Its core components include a compressor, evaporator, condenser, circulation pump, and intelligent temperature control module.
1、 Preparation before operation
1. Environmental condition verification
-Space requirement: Reserve ≥ 50cm of operating space around the equipment, ensure good ventilation, and stay away from heat sources and corrosive gases.
-Power configuration: Use an independent grounded socket, and control voltage fluctuations within ± 10% of the rated value to avoid sharing lines with other high-power devices.
-Medium selection: Select the appropriate medium based on the target temperature (e.g. anhydrous ethanol is required for temperatures below -20 ℃; specialized silicone oil is required for temperatures below -80 ℃), and direct use of water as a substitute for antifreeze is prohibited.
2. System initialization check
-Liquid level confirmation: Open the injection port and inject the medium until the liquid level is between the "MIN-MAX" scale line. When using for the first time, the air in the pipeline needs to be emptied.
-Sealing test: Before operation, check whether all interfaces are tightened, especially paying attention to whether the O-ring at the quick connect joint is intact.
-Alarm function verification: Short press the "TEST" button to simulate an over temperature/under liquid alarm and confirm that the sound and light signals are triggered normally.
2、 Standardized operating procedures
1. Startup phase
-Pre cooling program: Close the power switch, set the target temperature to 10-15 ℃ lower than the current ambient temperature, start the forced circulation mode and run for 30 minutes to enter a stable working condition of the system.
-Load connection: After the display screen shows that the actual temperature is close to the set value, slowly open the external equipment valve to avoid sudden flow changes that may impact the sensor.
2. Key points of dynamic regulation
-Gradient cooling strategy: For large temperature differences (>40 ℃), a segmented cooling method is adopted with a 2-hour interval between each stage to reduce the impact of thermal stress on the seal.
-PID parameter optimization: Long press the "SET" button to enter the engineer menu, adjust the proportional band (P), integration time (I), and differentiation time (D) according to the load characteristics, with typical values of P=60%, I=120s, D=30s.
-Abnormal monitoring: Record the inlet and outlet pressure difference (normal ≤ 0.1MPa) and current value (≈ 3A at full load) every hour. If there is a sudden increase of more than 15%, the machine should be stopped for troubleshooting.
3. Shutdown specifications
-Progressive shutdown: First adjust the set temperature to room temperature+10 ℃, run continuously for 10 minutes, then turn off the cooling, and finally cut off the main power.
-Emergency stop: In case of leakage or abnormal noise, immediately press the red emergency stop button, and it is strictly prohibited to directly unplug the plug.
3、 Typical Fault Quick Check Manual
Phenomenon 1: Unable to start
Reason: Power phase loss/overload protection triggered
Diagnosis: Measure the balance of three-phase voltage, reset the thermal relay
Repair: Replace the burnt fuse, clean the dust accumulation on the cooling fan
Phenomenon 2: Large temperature fluctuations
Reason: Improper opening of expansion valve/insufficient refrigerant
Diagnosis: Observe the state of bubbles in the sight glass and the frosting of the low-pressure tube
Repair: Adjust the length of the capillary tube and quantitatively charge the refrigerant
Phenomenon 3: Abnormal increase in noise
Reason: Bearing wear/pipeline resonance
Diagnosis: stethoscope locates noise source, infrared temperature measurement identifies hotspots
Repair: Replace double row ball bearings and add pipe clamp fixing points
4、 Efficiency Enhancement Techniques
-Energy saving mode application: Enabling the "ECO" mode can reduce energy consumption by 30%, suitable for low load conditions during the maintenance phase.
-Dual machine linkage scheme: When two units are running in parallel, the master-slave machine delay start stop is set to extend the compressor life.
-Cloud monitoring upgrade: Install IoT module to achieve remote monitoring of mobile APP and receive real-time warning information.
5、 Waste disposal standards
-Environmental recycling: Scrapped equipment must be disposed of by institutions with a Hazardous Waste Operation License, and unauthorized dismantling is strictly prohibited.
-Data cleaning: Delete experimental parameters within the control system to prevent sensitive information leakage.