Pollution Monitoring Equipment

Model 201LP Three Wire Triboelectric Detector / Broken Bag Detector

The Redkoh Model 201LP is a three wire particulate monitor that measures dust / particulate levels in air ducts on a real time basis.

The Model 201LP is powered by an external 24V dc supply and its continuous 4-20 ma output can be connected directly to a PLC, recorder, or digital readout. Changes in the 4-20 ma output are directly related to changes in the concentration of particulate in the gas stream.


Applications for the 201LP monitor include but are definitely not limited to process control, dry solid levels, and environmental applications such as:
  • Bag house / fabric filter
  • Truck and rail off-loading
  • Packaging stations
  • Feeders
  • Cyclone separators
  • Storage silos
Using an array of monitors on bag house compartments and/or outlet ducts is an excellent means of detecting broken bags before an emissions exceedance is reached. The units are found in industries wherever cloth filter bags and cartridge type filters are used in pollution abatement.

These include plants such as:
  • Coal fired power plants
  • Cement plants
  • Pulp and paper plants and many more.


Users of this type of equipment include OEMs who supply Baghouses and Fabric filters such as AAF (American Air Filters) and Clyde Bergemann as well as end users who own and operate such air pollution control equipment.


The Model 201LP system can detect a particulate loading as small as .0005gr/dscf (1mg/m3). There are five selectable sensitivity ranges to cover every requirement.

Broken Bag Detection

The Model 201 LP Broken bag detector is powered through a 24VDC signal. The 201LP is a cost-effective device for multiple compartment bag house applications. It is sensitive enough to not only detect broken bags, but also to detect the presence of worn bags.


  • Stainless steel probe lengths are available from 6” to 48” in 6” increments. Custom sizes can be supplied.
  • Standard 3-wire configuration with 4-20 mA output
  • Single opening to duct via ½” NPT coupling.
  • Electronics can be supplied separate from the probe for high temperature applications.
The Model 201LP monitor uses the Triboelectric principle to measure the electrical charge imparted by dust particles as they strike the probe The charge picked up by the probe is converted to an electrical current, which is measured by the electronic system.

Measurement System

Operating Principle:
Power Supply:

0.0005 gr/dscf (1 mg/m3)
4-20 ma


Probe Operating Temp:
Probe Material:

up to 400°F
316 SS with Teflon insulator
NEMA 4 / IP66


Electronic Enclosure:
Active Probe Length:

5.5”H by 2.9”W by 3.12”D
6” to 48” in 6” increments