Robertshaw Capacitance Level Probes
These probes are used with Robertshaw RF and microprocessor based ON/OFF or continuous level controls for measuring applications involving liquids or granular materials.
When the probe is used with an ON/OFF (fixed level point) type, it may be installed in the vessel in either a vertical or horizontal position. If, however, the probe is to be used on a continuous level measuring application or on an application with a differential (such as Pump On/Pump Off), then it must be installed into the vessel in a vertical position.
Bent probes are available to allow the active length of the probe to be different from the installation direction. See "Bending Specifications."
When the process is a conductive liquid (such as water or sulfuric acid) and the vessel is non-metallic or non-metallic lined, a probe with a ground wire may be employed to provide a ground path to the liquid (second plate).
The liquid must be clean and free of foreign materials and be no more viscous than water.
The Robertshaw Level Measuring instruments have been designed so that they attach directly to the 1/2" NPT fitting on the top of the probe. Typically, these are either the complete transmitter housing or a conduit outlet box with a coaxial cable to the instrument. The 6-32 threaded fitting in the end of the probe rod accepts either a contact pin or a machine screw as required.
Model 727A/C-B General Purpose Probe
The Model 727A is a High Pressure/Temperature Short-
Stop style probe for use in application where product
buildups or conductive coatings cause erroneous control
actions. The probe is manufactured of 316 stainless steel
with the nonmetallic components being of ceramic. The
probe is available in insertion lengths up to 96 inches
thereby ensuring the proper unit for each application.
The Model 727A probe has a pressure/temperature rating
of 1000 psi @ 800°F. IT IS NOT TO BE USED FOR
The process connection for the 727A is 1" NPT, with flanges being an optional item. The flanges can be screwed onto the probe gland or can be welded to the gland. When inserting the 727A probe into a vessel through a nozzle or other similar fitting, at least 5" of the short-stop element must extend into the vessel past the nozzle. This will ensure proper operation of the system in that particular application. THIS PROBE CAN ONLY BE USED WITH THE ON/OFF CONTROLLER THAT HAS THE SHORTSTOP OPTION (MODEL 5100).