Robershaw Capacitance Level products
This model has been discontinued
The can be used to measure the level of liquids and solids in a variety of tanks, bins, totes etc. These products are based on measuring the capacitance between a probe and the wall of the vessel. These are also classed as RF ( Radio Frequency) Admittance, RF Impedance level measuring devices. Robertshaw provide Control Units and Probes for Single Point, Multipoint ( two points on a single probe ) and Continuous ( 4-20ma current output). The continuous level measurement can be used with 4-20ma alarms to generate multiple alarms from a single probe. Units are avalable with general purpose enclosures and explosion proof enclosures for hazardous areas.
These units all require a capacitance probe to operate. See Probes
Robertshaw Model 158A Level Transmitter
The Robertshaw Model 158A capacitance to current RF transmitter is designed for remote mounting from the sensing probe and is used for continuous level measurement and control. Housed in a weather-tight or explosion-proof enclosure, with or without local indication, the Model 158A may be mounted up to 150 feet from the sensing probe allowing convenient and accessible installation.
A true DC current output signal, unaffected by varying load resistance, is produced which is directly and linearly proportional to input capacitance change. All calibration adjustments for the system are within the transmitter enclosure and are completely independent and non-interacting resulting in a simple "one-shot" calibration method. Wide adjustment ranges for both zero and span are provided to insure satisfactory operation on virtually any measurement application.
Unique circuit design concepts are employed in the Model 158A to effectively "cancel-out" the capacitance inherent in the Triaxial cable used to couple the transmitter to the probe. This permits the use of long lengths of interconnecting cable without any degradation in performance of the system -- and without the need for compensating cables, padding capacitors, or other calibration "tricks." Extensive use ofintegrated circuit operational amplifiers and other state-of-the-art semiconductors are used in the Model 158A to achieve reliability and long-term stability.
A wide variety of standard sensing probes for use with the Model 158A are available from Robertshaw to satisfy virtually any level measurement application.
- CSA Certified
- Independent and non-interacting adjustments- Simple initial calibration
- Remote mounting capability- Convenient installation location
- True Current Output Signals- Insensitive to load variations
- All solid-state circuitry- Long-term stability and reliability