Application case of Mini diaphragm pump replacing rotary vane pump in particle counting.
Background introduction：
Recently, the National Standards Committee issued GB/T 25915.1-2021 “Clean Rooms and Related Controlled Environments-1: Air Cleanliness Level”. The document was modified to adopt ISO 14644-1:2015 “Clean Rooms and Related Controlled Environments No. 1″ Part: Classification of air cleanliness levels according to particle concentration” and implemented on March 1, 2022.
According to relevant national standards, industries such as medicine, optics, chemistry, food, cosmetics, electronic health, biological products, aerospace, etc. have new requirements for air cleanliness in production workshops. In order to meet and comply with national standards, these requirements are Particle counting and testing equipment is widely deployed in production workshops with cleanliness requirements.
Include:
1. Testing of clean room (area) cleanliness;
2. Routine maintenance and monitoring of clean rooms in electronics factories and pharmaceutical factories;
3. Measurement of suspended particles in the air, etc.;
In the above-mentioned industries, particle counting equipment has become a widely used cleanliness monitoring equipment.
System principle:
The sampling air pump is used to pump the sample air into the cavity of the analysis instrument, and the dust particles of the sampled gas are counted using the principle of light scattering. Light scattering is related to factors such as particle size, light wave wavelength, particle refractive index, and particle absorption characteristics of light. However, in terms of scattered light intensity and particle size, there is a basic rule that the intensity of scattered light from particles increases as the surface area of the particles increases.
In this way, the gas to be measured is sucked into the measurement chamber through a mini diaphragm pump and passed through a beam of strong light, causing the particles to emit scattered light, which is projected onto the photomultiplier tube through the condenser lens, changing the light pulse into an electrical pulse, and calculating the number of particles from the number of pulses .
The particle diameter is obtained as a function of the intensity of light scattered by the particles and the particle size. In this way, the size of the particles can be inferred by measuring the intensity of scattered light, which is the basic principle of light scattering particle counting. According to flow classification, it can be divided into: small flow 0.1cfm (2.83L/min), large flow 1cfm (28.3L/min).
Application Difficulties of Mini Diaphragm Pump:
1. Online monitoring requires the mini diaphragm pump to operate continuously day and night, with long life and no need for downtime maintenance;
2. The imported rotary vane pump has a long supply period and high cost;
3. Monitoring instruments work in clean workshops for a long time and have extremely high requirements on the operating quality of pumps, requiring low noise and low vibration;
4. The mini diaphragm pump needs to be able to remotely start and stop, adjust the flow rate, and provide online feedback on the operation of the pump, so that the equipment can dynamically control the intake air sampling process;
5. Stable air flow. The stable flow of the mini diaphragm pump is an important condition for ensuring detection accuracy.
In the past, the industry mostly used micro rotary vane pumps as sampling pumps for particle counting. Although diaphragm pumps have a longer life, higher reliability, and lower costs than rotary vane pumps, diaphragm pumps are used instead of rotary vane pumps as sampling pumps for particle counting. Air pumps have always been restricted by flow pulsation, that is: the air flow output by the rotary vane pump is stable, which is conducive to particle counting, while the air flow output by the mini diaphragm pump fluctuates with the movement of the diaphragm, which we call flow pulsation.
For particle counting Sampling accuracy is affected by flow pulsation, making rotary vane pumps the mainstream choice in the particle counting industry. In order to solve the above problems: the FS flow stabilizer launched by our company can well balance the pulsation of the mini diaphragm pump, and the flow stability is almost the same as that of the rotary vane pump, so it can well replace the rotary vane pump in the particle counting industry.
At the same time, the current service life of diaphragm sampling pumps can reach 10,000 hours, while oil-free rotary vane pumps are difficult to achieve a lifespan close to that of mini diaphragm pumps due to mechanical wear.
Therefore, our company designed a solution to connect the mini diaphragm pump (C30L) and the flow stabilizer (FS series) based on this, which can not only solve the above application difficulties, but also better meet the application needs of the industry.
Solutions:
1.In order to have the low cost and long life of the mini diaphragm pump and the stable flow rate of the rotary vane pump, our company is the first in the industry: the application combination of mini diaphragm pump + flow stabilizer. The flow stabilizer eliminates gas pulsation and obtains the same results as the rotary vane pump. Smooth airflow while taking into account the many advantages of diaphragm pumps:
C30L is a mini diaphragm pump that uses DC 12V or 24v. It uses a high-quality brushless motor and has the advantages of long life, low interference, and high reliability.
FS0004A flow stabilizer is a gas flow stabilizing device that uses a buffering and flow-stabilizing structure to smooth out airflow pulsations and achieve good flow stabilization effects. It has a compact structure, no moving parts, and no wear, and has obvious lifespan advantages.
The effect of combining the two is:
It can be seen that after matching C30L-24V with FS flow stabilizer, in the 2880RPM speed range, the average flow rate is reduced from the original 4.35L/min and basically controlled at around 2.83L/min, and the PWM signal can be used to control the C30L air pump. Fine-tune the rotational speed so that its output flow rate is within the range of 2.83L-3L/min. The data is as follows:
The above data are based on test data without any components in the pipeline causing pipeline attenuation. If you are not sure whether there will be attenuation, you can use the C30L-42X model + flow stabilizer for testing. Adjust the knob to find the best speed until the flow rate is suitable. Then turn off the power and send the pump back to us. We will check the speed of the pump memory. And keep records. After that, we will customize a fixed-speed pump for you according to the recorded appropriate speed and ship it in batches.
2.We developed a new model D27E which has 5 pump chambers.comparing with the traditional mini diaphragm pump,there is no flow pulsation for this model.the average flow rate is about 3.7L/min.
