Tank blanketing valves – the key factor
Tank blanketing valves need to be of high accuracy, because this is the most important factor in tank farms. The key point in blanketing a liquid is to maintain the column of nitrogen in the vapour space. For this purpose, the vapour space must be pressurized or covered with nitrogen gas. The vapour gas pressure must be precisely maintained to ensure proper blanketing for safety. The pressure requirement is low because higher pressures do not significantly improve results. Increasing the blanketing pressure will cause more gas loss (typical blanketing pressure between 5 – 25 mbar). Tanks also have thin walls which are not designed for higher pressure. The result of poor control is wasting blanketing gas and not maintaining the necessary atmosphere within the tank.
⇒ High precision is most important for tank blanketing valves.
Body materials and elastomers
Tank farms can be found in many different places all over the world. They are exposed to wind, sometimes to very low or very high temperatures or to saline air. Tank blanketing valves should be made of stainless steel, so they are able to withstand aggressive evironmental impacts, also in the long term. High grade valve bodies allow for an effective outdoor installation.
Even inside a storage tank or the valve, things can get rough. The elastomers (e.g. seals and diaphragms) should still be resistant even if the inert gas mixes up with an aggressive medium. The materials also have to be suitable for all types of inert gases. Appropriate tank blanketing elastomers are: EPDM, FKM and PTFE e.g.
Self-acting tank blanketing valves
A positive feature of self-acting tank blanketing valves is that they have fewer components than valves controlled by external forces or energy. Fewer components result in faster installation, requiring fewer personnel. Self-acting tank blanketing valves perform with small failure probability and a high reliability. If no electronic equipment is needed, there is no cost for it. This does not have any impact on their function in case of a power failure. In addition to a long lifespan, our self-acting tank blanketing valves provide high control accuracy combined with quick response behavior.
Tank blanketing valves in a nutshell
- Excellent precision
- Resistant against aggressive evironmental impacts and fluids
- ATEX conformity possible