Monitor's line of microwave solids flow monitors are high quality, industrial grade instruments capable of providing a signal indicating the flow/no-flow condition of solids and powders in gravity chutes, feeders and pneumatic pipelines. The Model SFD-2 Solids Flow Detector provides relay outputs that can be setup to indicate changes in the target flow stream (on/off). The Model SFI Solids Flow Indicator provides an analog output which varies with changing conditions of the material flow stream. These non-contact monitors contain no moving parts or probes that can wear out or break off in the material flow, thus ensuring process integrity. The SFD-2 and SFI use low power microwaves to sense motion within the chute or pipeline being monitored. Microwaves are virtually unaffected by ambient noise and light, heat, humidity, pressure, vacuum, high or low temperatures or dust. This provides maximum effectiveness in typical industrial application environments. These advantages over sonic or mechanical flow monitors make microwave technology the best choice for solids flow monitoring.
Principle of Operation
Both the SFD-2 and SFI utilize a microwave transceiver (combination transmitter/receiver) enclosed within a watertight, dust-ignition proof powder coated aluminum housing with a screw-on/off cover. A process seal (Teflon® or Ryton®) acts as a transparent window through which the microwave energy is transmitted and the reflected return signal is received. The transceiver module generates and transmits a microwave signal into the area where material flow is to be monitored. The reflected microwave signal shifts in accordance with the Doppler Effect phenomena. The Doppler-shifted energy is analyzed to determine the appropriate output from the unit. The SFD-2 has a split-architecture design consisting of the transceiver and a separate power supply/conditioning circuit board. The relays are incorporated on the power supply/conditioning circuit board, which is optionally available with a fiberglass enclosure and indicating lights. With the SFD-2, the Doppler-shifted energy signal from the transceiver is carried back to the power supply/conditioning circuit board through the user-supplied signal and power supply cable. At the power supply/conditioning circuit board the signal intensity is indicated with an LED and converted into a relay output based upon the sensitivity adjustment. The power supply/conditioning circuit board provides the power to drive the transceiver and contains the controls for setting sensitivity, hold-off time delay, hold-on time delay and fail-safe selection. The SFI Solids Flow Indicator, unlike the SFD-2, consists solely of a transceiver. In this case the transceiver will receive its DC power through the user supplied signal cable and power supply. The three-wire design allows the user to monitor the analog output while providing the supply power to the unit. The Doppler-shifted energy is relative to the magnitude of the flow/no-flow condition that exists, when material velocity is constant, and this is reflected in the varying analog output signal.
Microwave Solids Flow Monitors - Models SFD-2 & SFI
- Senses Light And Heavy Materials, Small And Large Particles
- Non-Contact Sensor Detects Flow Through Most Non-Metallic Surfaces
- Non-Intrusive Flush Mounting. No Probe Protruding Into Material Flow
- SFD-2 Provides Relay Outputs and Convenient Remote Electronics
- SFI Solids Flow Indicator Provides Variable Analog Signal
- Sensors Include CSA Class II, Division I Approval for Hazardous Locations
Monitor's Solids Flow Detector and Indicator can be used in a variety of applications to detect flow/no-flow conditions of powders and solid materials. The selection of either SFD-2 Solids Flow Detector or the SFI Solids Flow Indicator is based upon the type of output required (relay or analog).
- Detection of a partial or full plug in a conveying line
- Detecting the bridging of material in a storage vessel upstream
- Sensing inadequate or a lack of flow due to upstream equipment failure (conveyor, blower, diverter valve, feeder)
- Verifying flow conditions
- Turning on/off equipment or processes downstream