Magnetostrictive Position Sensor Replacement – Part II

Magnetostrictive Position Sensor

As mentioned in our last post Magnetostrictive Linear Position Sensors are a common type of position sensor for hydraulic cylinders where high resolution is of primary concern.  The sensor incorporates a stainless steel tubular probe (ie. “the Rod”) and is surrounded by a short toroidal magnet installed in a counterbore in the piston. Magnetostrictive sensors can consume a fair amount of power and are not the most mechanically rugged sensor technology.  One of the key weaknesses of the solution for heavy duty hydraulic applications is the sensitivity of the hollow waveguide tube when faced with the high temperatures, shock and vibration commonly found in factory or outdoor environments. Even a small deformity of the tube compromises the basic operation of the waveguide and will cause a failure of the sensor.

Magnetostrictive Sensor Field Replacement in Hydraulic Cylinders

Plant managers operating steel mills, Oil & Gas refineries, waste processing facilities or almost any type of large scale manufacturing may have literally dozens of powerful hydraulic systems that employ position sensors. And the larger the stroke length, the more likely that high heat and gravity will make that long magnetostrictive waveguide sag over time until one day when the shaft bends sufficiently and gets hammered into a corkscrew by the retraction of the piston. A plant manager then has to maintain stock in each and every stroke length of sensor used on the premises in order to insure quick replacement is available.

The CPI SL series sensor is a perfect replacement for this technology, as it is designed to be a form-fit-function replacement for a magnetostrictive sensor in almost any cylinder of any stroke length. Furthermore the properties of the sensor address almost every weakness of a magnetostrictive position sensor in a heavy duty environment.

A Better Solution for Magnetostrictive Sensor Replacement.

Hydraulic Accumulator Position SensingThe CPI SL series picks up where traditional magnetostrictive sensors leave off.  The sensor technology is completely non-contacting, and is a drop-in replacement for existing magnetostrictive sensors in long stroke applications. No core drilling of the piston rod is required at all because the sensor can be screwed into the bore left behind by the broken magnetostrictive sensor Once CPI SL series position sensor can cover stroke lengths from 10” to 10 meters.

  1. The sensor fits easily into the bore used for the magnetostrictive sensor, no core drilling of the piston rod is required.
  2. The sensor can provide either analog voltage in 5 different ranges, or analog current output in the standard 4 to 20ma range.
  3. The sensor provides absolute position with pushbutton auto-calibration for ease of endpoint scaling.
  4. The sensor has a greatly improved temperature range up to 300F. Magnetostrictive sensors are typically rated to 170F max.
  5. The sensor LVDT based, can be mounted internally or externally and is inherently much more immune to EMI than a magnetostrictive sensor.
  6. The sensor is fully qualified in the field to operate in this application for over 1 million cycles.

About CPI’s LVDT based Linear Position Sensors

CPI is a US based manufacturer of precision waterproof switches, electro-mechancial thermal switches and linear position sensors. Heavy duty materials and robust performance characterize all of CPI’s products. Custom designed and off the shelf products in each category satisfy the most demanding operational environments. Industries served include Oil & Gas, Heavy Industry, Production Equipment, Mining equipment, Naval and Boat Industries, Safety, and Construction Vehicle manufacturers as well as dozens of others.

If you are frustrated with the performance of magnetostrictive sensors in your application, you can replace them with something better, without fear.  Call CPI today to discuss your needs for reliable, robust, hydraulic cylinder position measurement.