Pollution Monitoring Equipment

Model 201LP Two Wire Triboelectric Detector / Broken Bag Detector

The Redkoh Model 201LP is a two wire 4-20mA particulate monitor that measures particulate levels in air ducts on a real time basis.

The Model 201LP is powered by an external 4-20mA loop and 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 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 a loop powered device. 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.


  • NEMA 4X enclosure
  • Stainless steel probe lengths are available from 6” to 48” in 6” increments. Custom sizes can be supplied
  • Standard 2-wire configuration with 4-20 mA output
  • Single opening to duct via ½” NPT coupling
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:

4-20mA Loop Powered
0.0005 gr/dscf (1 mg/m3)
4-20 mA


Probe Operating Temp:
Probe Material:

up to 400°F
316 SS with Teflon insulator


Electronic Enclosure:
Active Probe Length:

4.5”H by 3.5”W by 4”D
6” to 48” in 6” increments