A corrosive substance is one that will attack, damage or even destroy other substances it comes in contact with. Corrosion can affect many materials, including metals and plastics, and literally consumes the material, leading to an array of problems. It is such an issue, that it is often a major part of maintenance costs, meaning corrosion prevention is something to consider in many applications.
Pressure transmitters and transducers are used in a multitude of applications and may be exposed to a number of corrosive chemicals and gases. These chemicals can attack the instruments both internally and externally, usually from leaks or fumes. Electronics and wiring may corrode which will often lead to failure of the transmitter. The product must therefore be protected from chemical exposure through good design and appropriate selection of materials of construction.
So here is some information to help you consider whether the materials used in the construction of your selected pressure transducer or transmitter are suitable for use with the media to be monitored;
Are you experiencing problems with corrosion of you pressure measurement equipment? Are you choosing the correct materials for the application?
In some applications the pressure media may be incompatible with the sensing element, in others it might be with the materials used to assemble the transmitter such as the pressure port or thread, o-ring or cable. You need to establish which parts of the transmitter will come in to contact with the media, or the “wetted parts” and how. Is there a risk that your transducer or transmitter will be splashed or open to vapour? Or perhaps it could become submerged?
So where do you begin to choose the correct transmitter for the job?
Firstly the constituent elements of the media must be identified before you can ensure that the construction of the transmitter is able to resist them in the short and long term. It is also important to remember that corrosive media can potentially become more aggressive as temperatures and pressures increase. Most metals corrode on contact with acids, bases, salts, oils, aggressive metal polishes, detergents and other solid and liquid chemicals. Metals will also corrode when exposed to gaseous materials such as acid vapours, formaldehyde gas, ammonia gas, and gases containing sulphur. The use of notoriously hazardous chemicals such as sulphuric acid and hydrochloric acid are certain to ring the alarm bells, but what if you are measuring seemingly risk free liquids like seawater or fruit juices?
How can we help?
Specialised manufacturers of pressure transducers and transmitters such as ESI Technology Ltd offer a comprehensive selection of materials in order to achieve the desired level of corrosion resistance for your application. By utilising the benefit of years of knowledge and experience in this field, ESI can advise you on the best sensor option combined with machined housings and threads in specialised metals and plastics to create a product that will operate safely and reliably at high levels of performance, even in the most corrosive of environments.
Standard ESI transducers are manufactured using 316L stainless steel and work effectively with most everyday types of gases and liquids such as nitrogen, oxygen, air systems, lubricants, coolants and hydraulic oils.
Pressure transducers and transmitters made from Titanium also feature heavily in our portfolio. Titanium (Ti) has a combination of properties that makes it unique and has proven to be technically superior in a wide range of industrial and commercial applications. It is the only metal that combines high strength and very light weight with outstanding heat and corrosion resistance making it particularly suitable for most pressure measurement applications.
Our Silicon-on-Sapphire pressure transmitters and transducers have wetted parts and diaphragms that are machined from a single piece of titanium alloy which means no weld joints and therefore high pressure integrity and overload capacity.
Where the media is known to be corrosive, such as subsea environments (http://www.esi-tec.com/2013/01/subsea-solutions-from-esi/) chemical processes, and some food processes, ESI transducers can be manufactured from Titanium, Hastalloy C, Inconel or PVDF for example. These non-standard products can be tailored to your unique application needs via ESI’s custom design service (http://www.esi-tec.com/2013/02/no-compromise-necessary/). Sensor technology, pressure port threads, output signals, pressure ranges, electrical connections and wetted parts can be adapted to withstand different levels of corrosion. Stringent quality control and inspection is exercised at every stage of the manufacturing process to ensure complete satisfaction with the end product, backed up with technical advice and support.