Q: How do I select the correct instrument?
A: The type of dust or particulate monitor required will depend on the application as well as local environmental regulations. By completing a simple Customer Enquiry Form, we will be able to advise a suitable sensor.
Q: Do I need to measure opacity or concentration?
A: This will depend on the regulatory authority and local regulations.
Q: What else do I need to consider when selecting an instrument?
A: A number of parameters need to be considered such as where the dust monitor is to be installed and the type of exhaust gas / flue; the stack diameter; power requirements etc. However, by completing a simple Customer Enquiry Form, we will be able to advise a suitable sensor.
Q: Why use light transmission techniques?
A: Transmissometry is a well proven technique and approved by many regulatory authorities as a suitable monitoring method.
Q: What are the advantages of the light transmission technique?
A: This method provides continuous measurement; it is relatively low cost and requires minimal maintenance.
Q: What do the instruments measure?
A: The instruments measure opacity (%) and by using an isokinetic gravimetric test, opacity can be converted to dust concentration in mg/m³.
Q: When would I use the Dynamic Detection Principle type instruments?
A: In order to determine which method is most suited to a given application it is necessary to consider factors such as the typical size distribution of the particulates to be measured, whether they have constant or variable physical properties and the ease of which the heads can be accessed for routine cleaning of the optical surfaces. DDP is best suited to applications where the mean particle diameter is >10μm.
Q: What are the advantages of the Dynamic Detection Principle ?
A: One key advantage of DDP over opacity is that by measuring the ratio of the noise variance to the mean transmission the resulting signal is almost independent of the mean transmission value. This means that the instrument can tolerate higher levels of optical contamination and greater optical misalignment before the measurement sensitivity is affected.
Q: What light source do you use?
A: A green LED light source is used, which works in the visible spectrum, offering long life and stability.This also meets environmental compliance requirements, globally.
Q: Is the instrument affected by ambient light?
A: The transmitted light beam is pulsed to provide complete immunity to ambient light. The intensity of the transmitted light is also monitored at source to compensate for any variations in the emitted light.
Q: How is the instrument mounted?
A: The TX and RX heads must be mounted directly opposite each other across the stack or duct so that light from the TX passes through the centre of the duct and falls directly onto the RX.
Q: Do I need an air purge?
A: Yes, to ensure that the optical surfaces exposed to the gas stream are kept as clean as possible. This is the same for all optical instruments if they are to be reliable and not require excessive maintenance.