The safety protection measures for graphite furnace atomic absorption spectrophotometer are as follows:

1、 Gas safety

1. Gas selection and storage

Acetylene gas source: A dedicated pressure reducing valve must be used and an anti backfire device must be installed. Acetylene steel cylinders should be placed in a separate ventilated room, away from oxidizing gases (such as oxygen), and replaced with new cylinders when the pressure is below 0.3 MPa.

Combustion supporting gas: The air outlet pressure should be controlled at 0.25-0.3MPa. It is strictly prohibited to use oxygen instead of air for ignition experiments to avoid the risk of explosion.

Argon protection: Graphite furnaces require the use of argon gas with a purity of ≥ 99% as a protective gas to prevent oxidation of graphite tubes. The flow rate of the internal air path is controlled by software, while the flow rate of the external air path needs to be maintained at 1.2-1.5 L/min to avoid damage to the graphite tube caused by insufficient flow.

2. Gas path inspection and operating standards

Pre ignition inspection: Before each ignition, it is necessary to confirm that the water seal of the waste liquid pipe is intact to prevent backfire. Use soap water or leak detector to check the sealing of the air path, with a focus on inspecting the explosion-proof plug at the rear of the atomizer.

Ignition sequence: Turn on air first and then turn on acetylene for ignition. When turning off the engine, turn off acetylene first and then turn off air to avoid backfire. Operators are not allowed to leave, and the remaining gas in the pipeline must be burned after the experiment is completed.

Emergency handling: If you smell an odor or hear an alarm sound, immediately turn off the gas source and power, check if there is a leak in the gas circuit, and strictly prohibit ignition in a leaking state.

2、 Electrical safety of graphite furnace atomic absorption spectrophotometer

1. Power configuration

The graphite furnace requires 380V power electricity (3-phase live wire+ground wire), and the instantaneous current during heating is relatively high. An independent switch (≥ 30A) should be equipped and pressed tightly against the wire end to avoid poor contact and fire hazards.

Separate the power cord from the host to avoid sharing sockets with other devices and prevent overload.

2. Anti electric shock measures

It is strictly prohibited to touch the graphite furnace body during operation, especially in the heating state, to prevent electric shock or burns.

Regularly check the connection status between the graphite tube protector electrode and the graphite tube to ensure good contact and avoid abnormal current fluctuations.

3、 Protection and maintenance of graphite furnace atomic absorption spectrophotometer equipment

1. Maintenance of core components of graphite furnace

Graphite tube replacement: Determine the timing of replacement based on sample concentration and reproducibility. If the sample contains strong oxidants or has abnormal absorbance, it needs to be replaced in advance. The new graphite tube needs to be air burned 3-4 times (heat treatment) to remove impurities.

Graphite cone cleaning: Before replacing the graphite tube, wipe the graphite cone with an alcohol swab to remove impurities and let it air dry naturally to ensure a tight installation.

Injection needle positioning: Adjust the position of the injection needle so that its tip is tangent to the contact edge between the sample droplet and the graphite tube, to avoid droplet residue affecting the results.

2. Optical system protection

Quartz window cleaning: Regularly rotate and unscrew the quartz window, clean it with alcohol swab and lens cleaning paper to ensure light transmittance.

Anti strong light exposure: Avoid direct exposure of the photomultiplier tube (PMT) to strong light to prevent signal distortion.

3. Environmental control

Temperature and humidity management: The laboratory temperature is controlled at 15-30 ℃, with humidity ≤ 70%, to avoid water vapor erosion of circuits or static electricity accumulation.

Exhaust system: Install an exhaust hood above the graphite furnace, with moderate air volume (too much can cause unstable flames, too little can affect the exhaust effect).

Anti vibration and electromagnetic interference: Keep away from vibration sources and electromagnetic radiation sources (such as large motors and high-frequency equipment) to prevent signal interference.

4、 Safety alarm and emergency response of graphite furnace atomic absorption spectrophotometer

1. Automatic alarm function

Insufficient pressure alarm: When the pressure of gas or auxiliary gas is lower than the set value, the supply will be automatically cut off.

Automatic shutdown: When the flame unexpectedly goes out, the gas valve will be automatically closed.

Cooling water flow alarm: prevent graphite tubes from overheating and burning due to insufficient cooling.

2. Emergency operation procedures

Gas leakage: Immediately close the main valve of the gas source, open doors and windows for ventilation, and prohibit the use of open flames or electrical switches.

Equipment malfunction: Press the emergency stop button, cut off the power, and contact professional personnel for repair.

Fire treatment: use dry powder extinguisher to extinguish the fire, and it is strictly prohibited to use water or foam extinguisher.