Laboratory low-temperature constant temperature bath

Laboratory low-temperature constant temperature bathInstallation and Maintenance Full Process Guide

1、 Installation process: refined operation from environment preparation to system debugging

1. Environmental assessment and preparation before installation

Site selection requirements: A dust-free, vibration free, and strong magnetic field interference free location should be selected, with a ground flatness error of ≤ 3mm/m ². An operating space of ≥ 80cm should be reserved around the equipment to ensure heat dissipation and ventilation.

Environmental parameter control: The room temperature should be stable at 10-35 ℃ (ideal 25 ℃), and the humidity should be ≤ 80% RH. High precision scenarios require a constant temperature and humidity system to avoid temperature fluctuations affecting temperature control accuracy. Equipment should be kept away from heat sources, corrosive gases, and flammable and explosive materials. For example, chemical laboratories should maintain a distance of at least 1.5m from fume hoods.

Electrical and safety configuration: The power supply should match the equipment nameplate requirements (such as 220V/50Hz or 380V three-phase power), and be equipped with a dedicated leakage protection switch (operating current ≤ 30mA). The grounding resistance should be ≤ 4 Ω, and grounding stakes should be installed if necessary. The power cord should use flame-retardant cables and avoid using extension cords or non-standard sockets.

2. Equipment positioning and mechanical installation

Basic positioning and fixation: Use a level to adjust the equipment to a horizontal state (error ≤ 0.5 °), and fix it with anchor bolts or shock-absorbing washers. All steel structure equipment requires seamless welded cabinets, and steel wood structures must ensure a load-bearing capacity of ≥ 300kg/m ². The distance between the equipment and the wall is ≥ 80cm, which is convenient for maintenance and heat dissipation.

Component connection and medium filling

Circulating system: Internal circulation requires short circuiting of inlet/outlet pipes to form a closed loop; External devices (such as reaction vessels) need to be connected for external circulation to ensure that the hoses are not twisted or leaking. The flow rate of the circulating pump needs to match the tank volume (such as a 300L tank requiring a flow rate of ≥ 6L/min).

Medium selection and filling: Select the medium according to the temperature range - water or deionized water at 5-85 ℃; -Use 55% ethylene glycol+45% aqueous solution below 30 ℃; Special silicone oil for ultra-low temperature (below -80 ℃). The filling amount should cover the refrigeration coil (with a liquid level 10-20mm above the "MIN" line) to avoid damaging the heater due to idling.

Electrical and control system connection: Connect the power cord, sensor (such as PT100), and control panel according to the instructions. Air cooled equipment needs to check the direction of the fan rotation (forward rotation can run, reverse rotation requires adjusting the phase sequence).

3. System testing and debugging

No load test run: Turn on the cooling, heating, and cycling functions, and observe whether the temperature curve is stable (fluctuation ≤ ± 0.1 ℃). Check for any abnormal noise from the compressor and circulation pump, and ensure good heat dissipation from the condenser (air-cooled fin temperature ≤ 60 ℃).

Functional verification: Conduct multi-stage program temperature control testing (such as gradient cooling crystallization) to verify whether the PID parameters match the load characteristics. Test safety functions such as over temperature protection and overload protection to ensure that alarm devices (such as buzzers and LEDs) are functioning properly.

Accuracy calibration: Use a standard thermometer (accuracy ± 0.01 ℃) to calibrate at three points: low temperature (-20 ℃), medium temperature (25 ℃), and high temperature (80 ℃). If the deviation exceeds ± 0.5 ℃, adjust the calibration coefficient.

Laboratory low-temperature constant temperature bathMaintenance work: systematic management from daily maintenance to deep maintenance

1. Daily maintenance (daily/weekly)

Cleaning and inspection: Clean the casing and control panel daily to avoid dust accumulation that affects heat dissipation. Check the liquid level and purity of the medium every week. If turbidity or sedimentation is found, it should be replaced in a timely manner (water quality medium should be replaced every 3 months, oil should be replaced every 6 months).

Operation status monitoring: Real time observation of temperature curve, circulation pump flow rate, compressor pressure and other parameters. When temperature fluctuations exceed ± 1 ℃, it is necessary to check the sensor, PID parameters, or circulation system.

Safety device testing: Monthly testing of emergency stop buttons and leakage protection devices to ensure rapid power outage in emergency situations. Check the grounding resistance and insulation resistance (≥ 0.5M Ω) every quarter.

2. Regular maintenance (quarterly/annual)

Refrigeration system maintenance: Clean the condenser fins quarterly (using compressed air or a soft bristled brush) to ensure heat dissipation efficiency. Check the refrigerant pressure every six months (such as high pressure 1.2-1.6MPa and low pressure 0.3-0.5MPa in R404A system), and supplement or replace it if necessary. Replace the compressor lubricating oil (such as specialized refrigeration oil) and clean the dry filter every year.

Heating and circulation system: Check the heating tubes and heating wires for aging and the bearings of the circulation pump for wear every quarter. Calibrate temperature sensors (such as PT100) every six months to ensure accuracy of ≤± 0.1 ℃.

Sealing and anti-corrosion: Check the sealing ring and O-ring for hardening and cracking every quarter, and replace deformed parts in a timely manner. Ultra low temperature equipment needs to use closed cell foam insulation materials to prevent condensation water leakage. The inner wall of the tank can be sprayed with anti-corrosion paint to prevent medium corrosion.