Steam Filtration

Within industry and manufacturing steam is an essential utility, used as a heat source, for cleaning, and sterilisation. Steam was chosen because it can hold significant amounts of potential energy, easily transported around facilities, and is used either directly or indirectly. Steam is also sterile, which makes it ideal for food and pharmaceutical manufacturing processes and sterilisation in hospitals and laboratories.

However, for steam systems to be at their most efficient and for the protection of process equipment, such as cartridge filters or storage tanks, steam needs filtered to remove pipework contaminants. This prevents fouling of pipework systems carrying the steam and ensures that these contaminants are not introduced to the manufactured product.

Why is this important? The temperature of the steam is set by the pressure that it is at. Steam at 1 bar gauge pressure is 121^oC. If the contaminants in the steam fouled the pipework system this would lead to pressure drop and the steam temperature would then fall. As sterilisation is based on exposure over time at a particular temperature then this could have a detrimental impact. This in fact would have a double impact as more energy is necessary to get the steam back to the correct temperature causing higher costs and lower efficiency of the process.

Dependent on the application of the steam then the filtration requirements differ as follows:

• Process steam used for heating, steam jackets and bio-hazard destruction filtered to 5 microns
• Culinary steam that comes into direct contact with food or food manufacturing equipment must be filter to less than 2 microns. Requirements defined by standard 3A-609-03.
• Clean steam used in the healthcare/pharmaceutical industry as it comes into direct contact with the product. initially prefiltered to less than 2 microns, as culinary steam and then further filtered by PTFE membranes to ensure 100% removal of magnetite particles. Magnetite particles occur due to the corrosive nature of high purity clean steam on st.st. pipework. Standard HTM 2031:1997 defines the filtration requirements.

The solution to all these requirements is to use cartridge filters manufactured in st.st and dependent on flow rate sintered st.st. cartridges for low flows or pleated st.st. cartridges for higher flowrate. The all st.st construction ensures that the filters can survive in the conditions over prolonged periods of time. Replacement of steam filters can be more than 5 years, but they do require regular cleaning during their service life.