Total migration evaporation residue testerIt is a key equipment used to detect the total amount of residue transferred from food contact materials (such as plastics, rubber, coatings, etc.) to food simulants under specific conditions. Its maintenance directly affects the accuracy of test results, equipment lifespan, and laboratory safety. From the followingDaily cleaning, maintenance of key components, calibration and verification, troubleshooting, safety protectionFive dimensions, systematically explain the key points of maintenance and upkeep:

1、 Daily cleaning and basic maintenance

1. Cleaning of testing chamber and sample holder

• cleaning frequency：
  • After each testImmediately clean the testing chamber and sample holder to prevent residues (such as grease, pigments, chemicals) from corroding the metal surface or contaminating subsequent testing;
  • Weekly deep cleaningUse a soft cloth dipped in neutral cleaning agent (such as deionized water+a small amount of detergent) to wipe the inner wall of the test chamber, avoiding the use of strong acids, strong bases, or organic solvents (such as acetone, ethanol) to prevent damage to the coating or seals.
• Cleaning Method：
  • Detachable componentsFor example, sample racks and evaporating dishes need to be removed and washed with a soft bristled brush, then rinsed with deionized water, dried, and stored;
  • Stubborn residueFor the residue of carbonization after high-temperature testing, it can be gently scraped off with a wooden or plastic scraper to avoid scratching the metal surface;
  • Drying treatmentAfter cleaning, dry with compressed air or dust-free cloth to prevent rust caused by residual water stains.

2. Maintenance of condensing system

• Condenser tube cleaning：
  • once a monthTurn off the device power, remove the condenser tube, rinse the inside with deionized water to remove scale or microbial growth;
  • chemical cleaningIf the condenser tube is severely scaled, it can be cleaned by circulating 5% citric acid solution for 30 minutes, and then rinsed with deionized water until neutral;
• Cooling water management：
  • Use deionized water or distilled water as cooling water to avoid mineral deposits in tap water blocking pipelines;
  • Regularly replace the cooling water (recommended every 3 months) to prevent bacterial growth;
  • Check the cooling water flow rate (usually 2-5 L/min) to ensure condensation efficiency.

3. Maintenance of ventilation system

• Ventilation hood/exhaust fan inspection：
  • Check weekly whether the air inlet/outlet of the built-in exhaust fan of the fume hood or equipment is unobstructed, and remove dust or foreign objects;
  • Blow the interior of the ventilation duct with compressed air every month to prevent residue from blocking and causing poor exhaust;
• Activated carbon filter replacement：

  • If the equipment is equipped with an activated carbon filter (for adsorbing organic volatile compounds), it should be replaced every 6-12 months according to the frequency of use to avoid failure after adsorption saturation.

2、 Maintenance and replacement cycle of key components

1. Maintenance of heating system

• Heating tube inspection：
  • Every six months, use an infrared thermometer to check the surface temperature uniformity of the heating tube. If the local temperature difference is greater than 10 ℃, the heating tube needs to be replaced;
  • Avoid dry burning of the heating tube (such as starting the equipment when there is no liquid) to prevent damage;
• Temperature sensor calibration：
  • Contact the manufacturer or third-party organization annually to calibrate the temperature sensor (such as PT100), ensuring that the deviation between the displayed temperature and the actual temperature is ≤ ± 1 ℃;
  • Before calibration, the equipment needs to be equilibrated at the test temperature for 1 hour to eliminate the influence of thermal inertia.

2. Maintenance of mixing system

• Magnetic stirrer cleaning：
  • After each test, remove the agitator and rinse it clean with deionized water to avoid residue corrosion of the agitator surface;
  • If the mixer is worn (such as uneven surface), it should be replaced immediately to prevent uneven mixing from causing testing errors;
• Motor maintenance：
  • Add lubricating grease (such as high-temperature lithium based grease) to the bearings of the mixing motor every 2 years to reduce wear and tear;
  • Avoid excessive stirring speed (usually ≤ 500 rpm) to prevent liquid splashing or motor overheating.

3. Seal maintenance

• Sealing ring replacement：
  • Test chamber sealing ringEvery 500 tests or 1 year (whichever comes first), replace to prevent leakage caused by aging and cracking;
  • Sealing gasket for condensation systemReplace every 2 years to avoid damage to the circuit caused by coolant leakage;
• leak test：

  • Conduct monthly airtightness testing (such as filling with 0.1 MPa nitrogen, holding pressure for 5 minutes, and a pressure drop of ≤ 0.001 MPa to be qualified);

  • If there is a leak, it is necessary to check whether the sealing ring is installed properly or if there is damage.

3、 Calibration and Verification

1. Temperature calibration

• Calibration tool：
  • Using a temperature calibrator certified by metrology (such as Fluke 5627A), its accuracy should be higher than the device display accuracy (such as ± 0.1 ℃);
• Calibration steps：
  1. Place the temperature calibrator probe in the center of the testing chamber, close to the sample holder;
  2. Set the device temperature to 50 ℃, 70 ℃, and 100 ℃ (covering the commonly used testing range), and record the calibration instrument reading after the temperature stabilizes;
  3. If the deviation is greater than ± 1 ℃, adjust the equipment temperature parameters or contact the manufacturer for maintenance;
  4. The calibration report should record information such as calibration date, environmental temperature and humidity, and calibration personnel.

2. Verification of residual evaporation amount

• Standard substance testing：
  • Use standard substances with known migration amounts (such as polyethylene standard samples) and conduct testing according to standard procedures (such as GB 31604.8);
  • The deviation between the test results and the standard value should be ≤ 10%, otherwise the equipment or operating procedures need to be checked;
• blank test：

  • Regularly conduct no sample testing (only adding food simulants) to verify the background value of the equipment (usually<0.1 mg/dm ²);

  • If the background value exceeds the standard, the testing chamber needs to be cleaned or deionized water needs to be replaced.

4、 Common faults and troubleshooting methods

Fault phenomenon	Possible reasons	Solution
The temperature cannot reach the set value	Heating tube damage, temperature sensor malfunction	Replace the heating tube or temperature sensor and recalibrate it
Insufficient stirring	Stirring wear and unstable motor speed	Replace the mixer, check the motor bearings and add lubricating grease
Poor condensation effect	Blockage of condenser tube and insufficient flow of cooling water	Clean the condenser tube, check the cooling water pump and pipeline
Leakage alarm	The sealing ring is aging and the testing chamber is not tightened	Replace the sealing ring, reinstall and tighten the test chamber
Large data fluctuations	Power interference, poor sensor contact	Install a voltage regulator power supply and check the sensor connection wire

5、 Safety protection and operating standards

1. Electrical safety

• ground check：
  • Check the grounding wire of the equipment monthly for looseness or corrosion, ensuring that the grounding resistance is less than 4 Ω;
  • Avoid using equipment in damp environments to prevent the risk of electrical leakage.
• insulation test：
  • Every year, the insulation resistance of the equipment should be tested with a megohmmeter (such as 500V) and should be ≥ 1 M Ω;
  • If the insulation resistance is too low, check whether the circuit board or motor is damp.

2. Chemical safety

• Protection against corrosive substances：
  • When testing acidic or alkaline food simulants (such as citric acid, sodium hydroxide), chemical resistant gloves (such as nitrile gloves) should be worn;
  • Immediately rinse the testing chamber with a large amount of deionized water after testing to avoid residual corrosion of the metal surface.
• Organic solvent management：
  • If using organic solvents such as n-hexane and ethanol to clean parts, it is necessary to operate in a fume hood and keep away from sources of fire;
  • Waste solvents must be collected according to the laboratory hazardous waste treatment process and must not be dumped at will.

3. Operating standards

• Preheating and Balancing：
  • Preheat the device for 30 minutes after each startup to stabilize the temperature before testing;
  • When changing the test temperature, it is necessary to wait for the equipment temperature to reach the new set value (usually taking 15-30 minutes).
• Sample processing：

  • The sample needs to be cut to the specified size according to the standard (such as a diameter of 50mm) to avoid edge burrs scratching the testing chamber;

  • Before testing, the sample needs to be equilibrated at the testing temperature for 2 hours to eliminate thermal stress.

6、 Long term disuse and storage

1. Clean and dry：
   • Clean the equipment before stopping, blow dry all pipelines and testing chambers with compressed air;
2. Dustproof and Moistureproof：
   • Cover with a dust cover and store in a dry environment (humidity<60%) to prevent metal parts from rusting;
3. Regularly power on：
   • Power on and run for 1 hour every 3 months to prevent the circuit board from getting damp or the motor from getting stuck;
4. Record and archive：

   • Keep equipment maintenance records (including cleaning, calibration, troubleshooting, etc.) for easy traceability and management.