The gas automatic sampler achieves full process automation of gas samples from sampling to injection through precise control of the gas path system and software collaboration. Its core principles and steps are as follows:
1. Sampling stage: precise positioning and extraction
Sample positioning: The software control system (such as PLC) receives user set parameters (sample bottle number, position, etc.), drives the sample disk motor to rotate, and positions the target sample bottle below the injection needle.
Injection needle operation: The displacement motor controls the descent of the injection needle, punctures the sealing gasket (such as rubber stopper) of the sample bottle, and inserts it into the bottle. Some models are equipped with pneumatic or solenoid valve driven injection needles to ensure precise operation.
Sample extraction: A metering pump (such as a syringe or piston pump) is used to extract gas samples at a fixed dose under motor control. The extraction amount can be set through software (such as 0.5 μ L to 50 μ L adjustable) to meet different analysis needs.
2. Injection stage: gas path switching and sample introduction
Gas path switching: Switch the six way valve or solenoid valve group to the main path position, and connect the injection channel to the analytical instrument (such as gas chromatograph). At this point, the sample is carried by a carrier gas (such as helium) and enters the chromatographic column at the set flow rate.
Low residue design: After the injection is completed, the system automatically switches to the cleaning gas path and flushes the injection needle, quantitative ring, and other components with carrier gas or cleaning gas to avoid cross contamination. Some models adopt a dual six way valve structure to achieve synchronous injection and cleaning.
3. Full process automation control
Software collaboration: Users can set parameters (such as injection sequence, volume, speed, etc.) through the PC or touch screen, and the software generates instruction sequences to control actuators such as motors and valves to act in a sequential manner.
Intelligent feedback: The system monitors the injection status in real-time (such as needle position, valve status, etc.) and feeds it back to the software through sensors to ensure traceability of the process and abnormal alarms.
4. Key technical support
High precision injection: PID algorithm is used to control the metering pump, ensuring that the volume error of each injection is less than 1%.
Quick response: Electromagnetic valve switching time ≤ 50ms, suitable for high-throughput analysis requirements.
Diversified injection modes: Supports multiple injection methods such as gas pipelines, gas cylinders, sampling bags, etc., and can integrate pre-treatment technologies such as headspace and thermal analysis.