Tank blanketing valves are used in many industrial sectors, for example in pharmaceutical environments, chemical & petrochemical plants and food & beverage processing facilities.
 

Storage tanks often contain media wherein contact with atmospheric oxygen (auto-oxidation) or mixing with other gases and/or liquids would cause harmful effects. For example, a chemical reaction could potentially create an explosive, toxic or corrosive mixture. In the food and beverage or pharmaceutical industries, cleanliness is vital as the media will likely need to be kept fresh to avoid any contamination because of microbes getting into the storage tank.
 

To avoid any contamination or hazardous situations in these processes, the void volume in the tank head space is filled with an inert barrier gas (as a common example, people would use Nitrogen). This process is only possible with closed containers or storage tanks. The positive pressure of this “barrier gas” is kept as low as possible, to ensure the process is cost-effective.
 

 

 

How does Tank Blanketing work?

The “tank head space” is the remaining empty space between the filled level of the storage tank and the top of the tank cover. By introducing an inert gas cushion in a controlled manner, down at millibar pressures, will restrict any contact between the stored media and reactive substance (such as Oxygen). Inert (ie. poorly reactive) gases could be Nitrogen (N2), Carbon Dioxide (CO2) or Noble Gases, such as Argon (Ar).
 

Changes in storage temperature or filling/extraction from the tank could potentially cause the filling level to fluctuate, and as a result the inert gas pressure could vary in the tank. This is commonly known as “tank breathing”.
 

The focus of a tank blanketing system is to constantly maintain an inert environment, regardless of what could cause the volume change in the tank head space. Our self-acting control valves will effectively ensure the control of the gas supply or discharge.

 

When should Tank Blanketing be considered?

  • Combustible and Explosive Media - Tank blanketing prevents potential ignition of the stored media. For example, Nitrogen supplied into a tanks head space will reduce the level of oxygen that could cause a fire outbreak to a non-flammable concentration.
     
  • Toxic and Hazardous Media - Tank blanketing creates a positive pressure within a storage tank so that the formation of hazardous and toxic gases is avoided.
     
  • Food and Beverage - Tank blanketing creates a positive pressure within the tank so that in the event of any leakages only the seal gas escapes, and harmful microbes are prevented from getting into the tank. This helps to maintain a high level of product quality.

 

Tank Blanketing Applications Details

Our customer is a specialist system designer providing turn solutions to the food and beverage industry – and on this occasion they were working directly with a process plant to produce tuna oil.
 

We worked with the designer to provide a selection of self-acting pressure reducing and back pressure/overflow valves to a create a tank blanketing system to supply Nitrogen over the tuna oil containers. The successful products included our DM762 pressure reducing millibar control valves and our UV3.0 back pressure millibar control valves.  
 

Boiswood we selected for this job as we were able to assist the customer with sizing, recommendations and quotation of their bespoke valve requirements to deliver within the project timeframe, as well as offering “on-the-ground” technical support.

 

Features and Benefits of our Tank Blanketing Valves

  • Exact control pressures from 0.002 BAR (2 mBAR)
  • Long operational lifespan
  • Excellent surface quality and large control surface via lever mechanism
  • Corrosion resistant, low net weight and compact design
  • Tight valve closure for safe operation with toxic or hazardous media
  • Various connection types including aseptic flanges, tri-clamp connections or ISO clamps
  • Completely made of 316L Stainless Steel (1.4404 or better)
  • Elastomers available for FDA, USP Class VI or Hygienic HE5 standards
  • ATEX-Certified Versions available

 

We offer a complete range of standard and customised valves for a broad range of tank blanketing applications. Contact us today to find out more about how we can help you.