AMETEK Land 4750-PM Back-Scatter Laser Dust Monitor

AMETEK Land 4750-PM back-scatter laser dust monitor explained

The AMETEK Land 4750-PM is a stack-mounted particulate matter monitor that measures dust by back scatter. A 650 nm Class 3R diode laser is projected across the duct, and the light scattered back by the particles is collected on a detector, with stray light removed by the design of the instrument. The sensor carries a combined internal user interface, so inputs, outputs and set-up are all handled at one unit on the stack.

In the model name, “4750” is the model number and “PM” means particulate matter. The instrument is used as a PM-CEMS for compliance or process monitoring and is certified to EN 15267 by TUVdotCOM according to the manufacturer. Seven Star LLC supplies the 4750-PM in Oman and the GCC as an independent supplier in Muscat.

4750-PM technical specifications

How the 4750-PM back-scatter principle works

Particles crossing the laser beam scatter light in all directions. In a back-scatter instrument the receiver looks at the light returned toward the source, which allows transmitter and receiver to sit together in one sensor on one side of the stack. Compared with an in-situ transmissometer, there is no reflector or opposite-wall unit to align, which simplifies installation.

The optical path is preset to maximise the measurement across the stack, and the sensor has no moving parts. Zero and upscale checks are possible by inserting predefined filters chosen to suit the compliance requirement, and filter audit units support periodic linearity checks that demonstrate performance against national and international emission monitoring rules.

Sensor design and options for 4750-PM

All signals terminate at the sensor. Digital and analogue outputs go directly to the data acquisition system, which keeps cabling simple. The listed options are a calibration audit set, a manual test kit, a purge-fail sensor and alarm, a purge blower with blower cover and a flue gas blocker.

The flue gas blocker is worth noting: it is intended to protect the operator when the instrument is opened for a manual audit or maintenance while flue gas is present in the duct. Remote triggering of calibration is also mentioned as an option.

Where the 4750-PM fits in an emissions monitoring system

The 4750-PM suits combustion processes without condensed water and can be located after a baghouse or an electrostatic precipitator. Stack diameter must be between 1.5 m and 15 m for the specified path.

Related AMETEK Land products are the 4650-PM forward-scatter monitor, which uses a probe and separate control unit and offers a 500 °C probe option, the 4500MkIII compliance opacity and dust monitor and the 4400 opacity monitor. The 4750-PM has a single-body sensor and a measurement range up to 1000 mg/m³, whereas the 4650-PM range ends at 200 mg/m³.

Selection and ordering checklist for 4750-PM

• Stack or duct diameter: it should be 1.5 m to 15 m.
• Gas temperature: up to 250 °C and pressure within ± 20 hPa.
• Dust level: the instrument covers 0–1000 mg/m³ with a detection limit below 1 mg/m³.
• Flange: DN80 PN10/16 or 3 in 150 lb ANSI.
• Power: 100 to 230 V AC at site.
• Options: calibration audit, manual test kit, purge fail sensor, blower and cover, flue gas blocker.
• Compliance: confirm that the EN 15267 certification fits your regulator.

Installation, commissioning and maintenance for 4750-PM

Mount the sensor on a flange at a straight section of duct, away from bends and dampers where dust is stratified. Purge air at 30–40 litres/minute keeps the optics clear, and a purge fail alarm is an inexpensive way to avoid undetected contamination. Check the purge filter regularly, particularly where fine desert dust is present in intake air.

After installation, the sensor is correlated with manual extractive sampling and a site calibration is set. Maintenance consists of zero and upscale checks with the filters, window inspection, purge checks and periodic audit work according to the permit. The 9.6 kg unit is light enough to be handled by two technicians, but use safe access to the stack platform.

Typical applications in Oman and the GCC

AMETEK lists electricity generating units, industrial boilers, glass works, cement plants, metals refining and process heaters. In Oman these include power stations, utility boilers at desalination and industrial complexes, cement production and metal processing. The monitor is usually placed after the filter system so that the reading shows any breakthrough of dust.

High summer temperatures, humidity on the coast and airborne dust are the main environmental factors; the IP65 sealing and -20 to 50 °C operating range cover typical stack-side conditions, and a sunshade is sensible on exposed platforms.

4750-PM information to send with your RFQ

• Stack diameter, flange type and wall thickness
• Gas temperature and expected dust concentration
• Fuel or process and the particulate abatement upstream
• Required outputs and the receiving system
• Options wanted from the list above
• Delivery location, quantity and date

Documents and quotation

The AMETEK Land 4750-PM brochure is attached on this page. Please compare the specification table with your own stack data before ordering.

To receive a quotation, send the 4750-PM part number with the stack details. Seven Star LLC is an independent supplier based in Muscat.