Inerting, Purging, Sparging and Pressure Transfer

Inerting for Safe Storage of Chemicals

Atmospheric oxygen and moisture can result in unsafe, unprotected storage of active pharmaceutical ingredient (API) reactants. Employing pure, dry nitrogen in a vessel’s headspace (known as inerting) is very effective in displacing oxygen and moisture. Inerting prevents oxidation or moisture contamination by minimizing the level of oxygen; forming a protective, safe layer of gas over the contents of the tank or reactor. An inert atmosphere is particularly important when storing highly volatile substances or products prone to oxidation.

In addition to being a leading supplier of nitrogen, Linde also has the know-how to help you select and size the equipment you need for safe, effective inerting.

Purging to Replace Vessel Volume with Inert Gas

Purging is an inerting method commonly used in safety-critical process vessels such as reactors to eliminate oxygen and moisture when operations are started up or shut down. The three primary methods are displacement, dilution and vacuum purging. With displacement purging, an inert gas is injected into an open vessel to displace atmospheric air. Dilution purging involves injecting an inert gas to reduce the concentration of oxygen and moisture. In the case of vacuum purging, air is extracted with a vacuum pump and an inert gas is then fed into the evacuated vessel. Purging is also used to remove air from piping systems.

In addition, purging can be used to dispel flammable or poisonous gases. 

Purging is typically an initial step used to prepare a vessel before maintaining an inert atmosphere in the headspace.

Sparging to Displace Oxygen with Inert Gas

Sparging with inert gases like nitrogen or argon is used to strip oxygen from liquids such as API chemicals. Sparging involves passing finely dispersed gas bubbles through the liquid. This helps to improve mixing and increase the surface area for gas-liquid mass transfer. Consequently, this technique is not just used to strip oxygen from liquids, but also to intensify chemical and biological reactions.

Sparging can be used to preserve the quality and longevity of products by eliminating undesirable substances and inhibiting unwanted chemical reactions with oxygen. In the pharmaceutical industry, injecting a stream of fine gas bubbles is a fast, flexible and effective way to boost a chemical or biological reaction by increasing the available surface area between the two phases. We have years of experience specifying components used for effective sparging.

Pressure Transfer of Liquids with Inert Gases

Conventional methods used to transfer reactants from one vessel to another present a number of challenges. They often require special pump designs, compatible with the wide range of fluids which need to be transferred. In addition, even small failures of seals, especially on the suction side of the pump, can result in leakage of air or other ambient vapors into the fluid stream. In the case of high-quality synthesis reactions, such impurities can lead to product rejections. In addition, rotating equipment like pumps require ongoing maintenance and can be prone to failure, which can be very disruptive to chemical production operations.

Pressure transfer using pure dry inert gases like nitrogen offer a simpler and safer alternative to pumping. Pressure transfer does not require any rotating equipment and is therefore more reliable. The rate of liquid transfer can be regulated by controlling the gas flow rate and pressure. We have years of expertise in the proper specification of pressure transfer systems and components.