Smart cylinders work deep under water

Moving massive flood gates poses no great challenge for hydraulic cylinders. But if the cylinder may sometimes be submerged under hundreds of feet of water, transmitting an electronic signal from an LDT (below) to a central control calls for special measures.

Flood gates are available in a wide range of categories and sizes and are the crucial component in water management and conservation in projects around the world. Due to their shear size and mass, flood gates are typically moved in position by hydraulic cylinders. These large cylinders need to vary the position of the flood gates according to the ever changing conditions.

Due to the design of the flood gate, these cylinders may be located temporarily or permanently under water. This poses a major challenge to sensors for monitoring position of flood gates because very few types of sensors can survive under these conditions. Because magnetostrictive position sensors provide an accurate, non-contact means of measuring linear distances even under high shock and vibration conditions, a magnetostrictive sensor was specified for this flood gate project.

Made to be submerged

Model PCST27 in-cylinder linear displacement transducers, from ASM Sensors, Elmhurst, Ill., combine the proven ruggedness of a magnetostrictive sensor with a permanent submersible housing required for this type of application. The all stainless-steel, pressure-tight housing that contains the sensor’s electronics and seawater-resistant cable allows the PCST27 to be used up to 100 m under water.

This sensor uses a magnetostrictive wave guide and a position magnet that is installed top of the piston in the hydraulic cylinder. To withstand the harsh underwater conditions, the sensor’s housing is completely sealed and tested to exceed IP68 and IP69K rating. The sensor has also been tested to be shock and vibration resistant.

The PCST27 has an operating pressure rating up to 5800 psi and a measurement range up to 19 ft, and it can be fitted to the majority of hydraulic cylinders. The sensor is available with analog output of 0-10 V, 4-20 mA or alternatively with a digital pulse output Start-Stop or Synchronous Serial Interface (SSI).

In addition to the compact design, this sensor is available with either 34-in. 16 thread or M18x1.5 thread for easy installation. The PCST27 is rated to tolerate 100, 50-G 11-msec shocks according to EN60068-2-27:1993. In case of malfunction, the electronic circuit and wave guide can easily be done without bleeding the hydraulic fluid. This precise position sensor also has a full scale linearity rating of ± 0.02%.

ASM Sensors Inc., headquartered in Moosinning, Germany, has its US headquarters in Elmhurst, Ill. For more information, call (630) 832-3202 or visit www.asmsensors.com.