Scattered-light aerosol spectrometer system with two sensors for quasi-simultaneous measurements

A touch display ensures user-friendly operation. Measurements can be started quickly, and all data, such as the current number distribution, number concentration, and 24 further statistical values, can be evaluated and displayed in real time.

Measurements are performed continuously with Promo® as a standalone measuring device (i.e., without an external computer)^® as a standalone measuring device (i.e., without an external computer), and measurements are performed continuously. All incoming data can be stored with a maximum temporal resolution of 1 s. Promo^® can therefore measure and save data over weeks independently. For data transfer, Promo^® can also be integrated into a company network.

The Promo^® has a standard interface and can be controlled by a process control system or a simple Labview program.

On Promo^® 3000, two welas^® sensors are supplied with one light source, and a photomultiplier detects the scattered light pulses. This enables a quasi-simultaneous particle measurement at two sampling locations up to 100 meters apart.

With Promo^® 3000, the user effectively has two scattered-light spectrometers in one device with the same device characteristics:

• Particle size resolution capability
• Particle size classification accuracy
• Counting efficiency
• Zero counting rate

The various welas^® sensors are characterized by perfect conformity of counting efficiency and particle size resolution (see product data sheet: welas^® sensors").

All welas^® 2000 series sensors can be used with the Promo^® 3000. The quasi-simultaneous particle size and quantitative particle determination offer particular advantages for characterizing separators with fluctuating raw gas concentrations.

Opto-mechanical switching

Using optomechanical switching, the two connected sensors can be easily controlled. The sensors are controlled automatically with the software.

The particular advantage over a manual measurement selector switch:

• Faster change of the measurement location
• No deposits in sampling lines
• Long service life; no wear of the seals due to dust particles

The Promo^® measurement technology

The Promo^® has a new, fast 20 MHz signal processing processor, which analyses the interference of each particle. This makes it possible to recognize coincidental events based on the scattered light signal, i.e., more than one particle in the measurement volume at one time can be identified from the individual signal and corrected (according to Dr. Umhauer / Prof. Dr. Sachweh).

This makes it possible to increase the maximum concentration limit to 10⁶ particles/cm³ (welas^® 2070 sensor). Also, low concentrations of < 1 particle/cm3 with the welas® 2500 sensor lead³ with the welas^® 2500 sensor lead to higher measuring accuracy.

High classification accuracy and large particle size resolution (see Graph 1) are guaranteed by the following special features:

• White light and 90° light-scattering detection ⇒Unambiguous calibration curve

• Patented T-aperture ⇒No border zone error

• New digital individual signal processing ⇒Coincidence detection and correction of the individual signal making it possible to measure higher concentrations.

Graph 1: Example with 2200 sensor

The Promo^® aerosol spectrometer is characterized by its high counting efficiency starting from 0.2 µm!

Graph 2: Example with 2200 sensor, in relation to LAS-X II