1、 System Overview:
The HJF-DQB series dust concentration transmitter measures the electrostatic induction of dust particles passing through a fixed probe. Dust particles and probes induce static charges, which are amplified by the probe and transmitted to the monitoring and control system. The size of static charge is proportional to the flow rate of dust particles. The electronic circuit of the system converts this part of the charge into a control signal output, activates the dust over limit emission alarm, and is used to continuously record the total amount or concentration of dust particles.
The HJF-DQB series device provides the world's new AC coupling technology, which is a modern, accurate, and stable monitoring technology, particularly suitable for continuous emission recording and data accumulation. The working principle of this monitoring system is to use the charge induction generated by the flow of dust particles around the probe to confirm the online emission amount (mg/sec) or emission concentration (mg/m3) of dust particles. Under relatively stable combustion conditions (i.e. at the same emission point, there is no significant change in flow rate, temperature, pressure, humidity, and particulate properties of smoke particles, with a variation of less than ± 90%), this system can also be used for online monitoring of emission concentration (unit=mg/M3) after direct calibration.
Compared to the HJF-DQA series, this system has added a local display function, which allows users to view the dust concentration status of this monitoring point at any time and make corresponding records.
2、 System application:
This system is applied in a wide range of industrial fields, including ceramic manufacturing, cement, fine chemistry, medicine, and food industry. In these processing fields, it is necessary to fully consider the recycling and utilization of dust to reduce the loss of raw materials during the processing. The dust emissions from factories are also restricted by air pollution control laws, local regulations, and other rules.
Air pollution control systems such as bag filters and electrostatic precipitators are used to isolate particles or dust from the airflow before being emitted into the atmosphere. By effectively treating the exhaust gas, the dust concentration in the exhaust gas is kept below a specified value, and continuous monitoring of the dust concentration in the treated gas is necessary.
School laboratories and research institutions need to simulate the dust environment and its impact in pipelines, and understand the changes in the environment inside the pipelines.
3、 System parameters:

operating ambient temperature	-20 ℃~60 ℃ (electronic components)
Operating environment humidity	Operating environment humidity
Operating environment vibration	Maximum continuous oscillation, any direction, any frequency: root mean square value 2g (20m/s2)
Operating environment electromagnetic field	At 50 Hz, the highest value is 60 A/m (equivalent to a magnetic field of 50 AT in a 1 × 1 meter square electromagnetic coil)
Protection of operating environment	Protection level: IP66/NEMA4 aluminum alloy shell, suitable for installation in non corrosive environments, stainless steel probe
Pipeline gas pressure	-0.1 – 1MPa
Pipeline gas flow rate	1m/s～30m/s
Pipeline gas temperature	－50℃～450℃
Pipe OD	0.1 meters to 4 meters
Probe structure	The standard probe is M6, with a length of 160 mm and a 316 stainless steel rod
Dust particle size range	The nominal range is 0.1 μ M to 200 μ M, and it can still receive signals outside the nominal range, but the signal characteristics are slightly different.
zero drift	(Time) Less than 1% of the range per year.
zero drift	Within the specified temperature range, below 1% of the measuring range.
Full-scale drift	(Time) Less than 1% of range per year
Full-scale drift	Within the specified temperature range, below 1% of the measuring range.
Line stability	All components of the system are made of high stability electronic assemblies.
Noise resistance	All 50 or 60 Hz audio and harmonics are filtered out before the signal is received
measuring range	0-9/12/25/50/100/200/400/800/10000 mg/M3 (larger quantities can be customized)
Transmitter output mode	2-wire system 4-20mA (built-in isolator, explosion-proof and anti-interference)
Transmitter power supply	15V – 32VDC

4、 System Connection Diagram

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