PVDF vs. Stainless Steel Transducers

By Eric Haun
Friday, June 13, 2014
Photo: American Sensor Technologies

While stainless steel submersible pressure transducers are proven to provide a reliable level measurement solution for many tank monitoring applications, transducers constructed with PVDF materials offer a longer term solution in certain harsh liquids.

Stainless steels do offer good compatibility for most common liquids from potable water to fuels. However, exposure to certain liquids might require either additional protection to a stainless steel transducer or require a PVDF-based sensor as an alternative.

Sacrificial anodes are a common accessory added to a stainless steel submersible pressure transducer to prevent the surface from corroding. When used, the sacrificial anodes are clamped onto the outside of the sensor’s housing, basically wrapping around it. The accessory adds cost, labor and will eventually require replacement at an unknown time based on the galvanic corrosion rate. A PVDF submersible sensor eliminates those requirements and costs, supporting a long-term installation.

While potable water on its own is not harmful to stainless steel, additives that condition the water can create corrosive properties that increase the speed of sensor breakdown. Whereas the chemical formulation of a liquid, sensor location and quantity of additives can limit the survivability of a submersible pressure transducer made from stainless steel, PVDF material offers greater compatibility with a wider range of liquids. For example, frac water level can be monitored with a submersible PVDF pressure sensor for a longer life expectancy than a comparable stainless steel unit. 

Bacteria in tanks is also common in wastewater, ship ballast tanks, and ultra-low sulfur diesel fuel tanks, causing clogging of pipes, sensors, and valves. While stainless steel can be eaten away by the bacteria in the tank causing premature failure, PVDF level sensors continue to operate without the worries of clogging or breakdown.

The Model AST 4530 Submersible Pressure Sensor is an example of a transducer constructed with PVDF material and a PTFE diaphragm to measure the level of harsh liquids such as slurries, salt water and oil in vented tanks or containers.  The pressure sensors also feature a submersible PVDF cable, cord grip and conduit connection for turbulent installations such as process plants, salt water holding tanks, on-board ships, turbulent tanks, and rail cars. 

astsensors.com
 

Maritime Reporter August 2015 Digital Edition
FREE Maritime Reporter Subscription
Latest Maritime News    rss feeds

Marine Materials

Automatic Camera for Monitoring Vessel Engine Developed

NYK and the Monohakobi Technology Institute  have jointly developed “Kirari NINJA” (patent pending), a device that can automatically photograph the interior of a vessel engine’s combustion chamber.

Occurrence of Humpback Whales at Franz Josef Land Recorded

Scientists first documented occurrence of humpback whales near the archipelago of Franz Josef Land. Experts attribute this to the successful development of their populations.

HII Wins $109.4mln U.S. Navy Contract

Huntington Ingalls  has received a $109.4mln contract modification to carry out support services for the U.S. Navy’s nuclear submarines.   The company will work to engineer,

Marine Equipment

Ballast Water System Retrofits for 11 Containerships

Eleven container vessels owned by Bernhard Schulte GmbH & Co. KG, based in Germany, are to be retrofitted with Wärtsilä Aquarius Ballast Water Management Systems (BWMS), Wärtsilä announced today.

ICTSI Manila Starts Container Booking System

The Manila International Container Terminal (MICT) in the Port of Manila has started implementing a vehicle appointment system called Terminal Appointment Booking

RORO Ops by NYK for Ford Plants in India

In 2011, NYK Auto Logistics (India) Pvt. Ltd.(NALI)* was awarded a contract by Ford India for RORO terminal services of finished cars at Chennai and Ennore Port.

 
 
Maritime Contracts Maritime Security Maritime Standards Navigation Offshore Oil Pod Propulsion Salvage Ship Simulators Shipbuilding / Vessel Construction Sonar
rss | archive | history | articles | privacy | contributors | top maritime news | about us | copyright | maritime magazines
maritime security news | shipbuilding news | maritime industry | shipping news | maritime reporting | workboats news | ship design | maritime business

Time taken: 0.1941 sec (5 req/sec)