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Behind the Purity: Pure Steam Generators in Pharma Production


In the pharmaceutical industry, nothing is more important than hygiene. As a manufacturer of vaccines, injectables, oral solid doses, biologics or any other pharma preparation, the safety of the people who use your products is paramount. Your standard operating procedures, your API and excipient suppliers, and your choice of equipment are significant factors which determine the safety of your products. Your choice of pure steam generator for pharma applications also plays a key role here, especially considering the fact that this pure steam will come in contact with the same surfaces as your sterile raw materials and final products.

What is pure steam?

Even though the term sounds fairly simple, pure steam – or clean steam – has a number of technical specifications in terms of purity, level of permissible endotoxins, and presence of non-condensable gases. It is distinguished from other types of steam based on its purpose and purity. Plant steam, for instance, is used mainly for heating systems and never comes into contact with products or equipment which need to be sterile. Process steam, on the other hand, is produced from pre-treated water with no corrosion-inhibitors or other additives; it is suitable for a larger range of activities in a pharma plant, but not for contact with sterile goods.

Pure steam, finally, is pyrogen-free, dry, saturated steam produced by a specialized clean steam generator for pharma; when condensed, it should meet the requirements of water for injection(WFI), as defined by the European Medicines Agency’s Guideline on the quality of water for pharmaceutical use, or as per the guidelines mentioned in other internationally accepted pharmacopoeia like the United States Pharmacopoeia or Japan’s Pharmacopoeia. Pure steam is used to prevent the contamination of process vessels, process piping networks, and other sterile ecosystems which involve direct contact between equipment surfaces and medical devices or pharmaceutical products.

The quality of the feed water used to make clean steam matters; pure steam may be produced by the distillation of purified water. An ideal pure steam generation system for pharma produces saturated steam from water free from additives and non-condensable gases. With a prescribed endotoxin level of less than 0.25Eu/ml, pure steam should meet the same criteria as WFI with regard to endotoxin level, conductivity and total organic carbon.

Pure steam, as an excellent heat transfer media, has special applications in pharma. A pure steam generation system for pharma would likely service your sterilization in place, or SIP, processes for process piping, tanks, reactors, and any other product contact surface. A pure steam generator for pharma may also be used for air humidification in controlled manufacturing areas where even the quality of air matters.

What is a pure steam generator?

A pure steam generation system for pharma involves the forced flow of incoming feed water which is converted to pure steam in a single pass. This conversion happens by means of heat transferred to the system via hot gases, plant steam or electricity. Obtained from the distillation of purified water, pure steam’s origins lie in water which has usually been treated using reverse osmosis to reduce the amount of impurities in it by using a semi-permeable membrane.

But quality has to be maintained not just before the stage in which the clean steam generator for pharma is used, but also after. During the distribution and application of pure steam, it should never come into contact with surfaces which might transfer contaminants to it. Maintaining this high quality involves a number of other steps like transporting the steam under pressure, preventing contamination by anti-corrosion additives, and more which we will discuss below.

What makes a good pure steam generator for pharma purposes?

When assessing the suitability of a clean steam generator for pharma applications, there are so many considerations you can add to your checklist to make sure you end up with a reliable system. Here are a few to get you started.

What’s it made of?

Durability and corrosion-resistance of the material of construction.

Pure steam moves through process piping and equipment under pressure. And under such pressure, corrosion of the piping network is a fallout that you might have to deal with. But not if your systems are made of high quality stainless steel, ideally SS 316L. Using this material, however, is not just a matter of durability. It is also a question of steam quality because if the materials used are not corrosion-resistant, the steam itself can get contaminated through contact. This is why TSA electropolishes all contact parts to less than 0.4 Ra microns and pre-passivates the system.

How’s it made?

Design intelligence.

Other than material of construction, you should also give serious thought to the design of your pure steam generator for pharma applications. Features like fewer moving parts minimize maintenance requirements and downtime; minimal internal components reduce your hassles when it comes to inspection, repair and maintenance; video-borescopes offer enhanced options for monitoring your systems and processes. Sustainability is also fairly important in today’s world, so design features which embed energy efficiency are a big plus.

Is it tailored for you?

Flexibility and customizability.

For your specific plant, the scale of operations and the pharma preparations you produce will determine how you implement a pure steam generation system for pharma-linked sanitary standards. You may need a flow rate ranging from 50 kilograms per hour to 1500. You may need pre-heaters, double tube sheeting, heat exchangers and other accessories or allied equipment to make your operation a success. Go for pure steam generators which offer high flexibility, like TSA’s, which has a variable production capacity of up to 80% with no additional plant modifications.

Getting tested.

Compliance and quality assurance.

When you choose a pure steam generator, ensure that it complies with current Good Manufacturing Practices (cGMP) as defined by internationally respected regulatory bodies like the US FDA or ASME. Validation documentation from your manufacturer is also essential and can be useful when you yourself test the pure steam for conductivity, non-condensable gases, microbial and endotoxin contamination, and saturation tests according to international and national requirements. Testing for some of these may be difficult in the vapour form, in which case its condensate is tested. But measures should be taken to ensure that the condensate collection process doesn’t affect its quality during testing.

Contamination control.

Microbial, chemical, endotoxin and air elimination.

As you can see, that’s a lot of contaminants that we have to control against in a pure steam generator for pharma. It is critical to prevent the occurrence of contaminants at the point of entry, via leakages, or through air getting pulled into the system. As a pharma manufacturer, you have to also be careful to prevent condensate from collecting in the system as that can become a comfortable home for bacteria. Even the presence of air in pure steam can reduce its optimal temperature and result in a failed sterilization process; effective interventions like steam traps, air vents or air eliminators must be employed to keep steam safe from airborne intruders.

Under pressure.

Controlling superheating.

Pressure drops in a pure steam generation system for pharma can lead to superheating, with heat losses from the piping causing the steam temperature to fall. When selecting a pure steam generator, make sure your system is designed to prevent pressure drops below 50% of the absolute supply pressure.

The clean steam generator you choose for your pharma facility is amongst the most important decisions you will make, so make it count. Use this guide to make an informed decision for yourself, your business, and the health and safety of your customers. 

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