Why Water Quality is Important When Using a Steam Autoclave
Water is the lifeblood of a laboratory autoclave. The quality of water used will drastically impact the lifespan of the autoclave chamber and steam generator, as well as the types of loads that can be sterilized. To understand why, let’s address four common questions about water quality and ways to remedy some of the issues you may be facing with your autoclave.
Can I Use Tap Water in My Autoclave?
It depends on the quality (e.g. hardness, minerals, chlorides, etc.) of your water. While many laboratories use tap water with their steam autoclaves, this practice can lead to costly downtime and expensive repairs over time, if the quality is not adequate. Tap water is certainly a practical source for creating steam, but it can also be destructive to your autoclave.
What Causes Tap Water to Damage My Autoclave?
Tap water contains a variety of dissolved minerals and salts. Depending on your geographic location and water source (ground well, lake, river, etc.) the amount of this dissolved content can be very high. The more minerals water contains, the “harder” it is. When hard water is boiled into pressurized steam or used to cool the waste, it leaves behind salt and mineral deposits within the steam generator, pipes, and valves. These deposits build up over time like layers of paint. As they build up, they decrease the efficiency and functionality of the steam generator in addition to clogging up pipes and valves. Consolidated requires that any water that is harder than 5 grains (85 mg/L) should be treated. The hardness of your tap water can be found in your municipal sewage report or by having a water quality test performed.
How Can I Purify My Water?
There are 3 ways to remove impurities from tap water:
- Reverse Osmosis (RO) – RO systems filter water by forcing it through a thin permeable membrane that removes most solid contaminants and dissolved minerals but does not remove biological particles, such as bacteria or viruses.
- Deionization (DI) – DI systems remove the ions from the water and produce a very high purity level. It does not affect uncharged molecules, viruses, or bacteria.
- Distillation – Distillation removes virtually all impurities from water by boiling it and then condensing the steam into a clean container. This process leaves nearly all contaminants behind.
For a carbon steel steam generator, often the easiest and least expensive water treatment solution is to install a Type III RO filter on your water line and install an “automatic generator blow-down” feature on your electric steam generator. The RO filter will retain the majority of the contaminants while the blow-down feature will flush away any minerals that do make it through, thereby greatly extending the life of the heating elements in the steam generator. Learn more about our Autoclave Water Purification Systems, designed to seamlessly integrate with all sterilizers and other laboratory equipment that require purified water.
How Pure Does My Water Need To Be?
Water between 0.1 megohm·cm to 1.0 megohm·cm (purity achieved with a Type III RO filter) would be appropriate for the vast majority of research lab sterilizer loads such bio-hazardous waste, clothing, cages, glassware, media, or general lab equipment. On the other hand, items very sensitive to mineral contamination, such as tissue samples or items used in cGMP processes, should only be sterilized by steam generated from water greater than 1 megohm·cm. Water of this purity is generally only achieved from DI and distilled purification. Keep in mind, when high purity water (greater than 1 megohm·cm) is used as the source for steam generation, the autoclave must to be constructed from stainless steel, specifically the chamber, jacket, steam generator and process piping. High purity water lacks ions or minerals and will try to leach impurities from everything it touches, including glass, steel, and copper. This could cause continuous corrosion and premature failure of non-stainless steel components.
For more about water quality and protecting your steam autoclave, visit our Smart Options page.
17 Questions to Ask Before Buying Your Next Autoclave
With so many models, sizes, options and components to choose from, how can you ever really know exactly what you need to make the most out of your investment?
These questions will help you to make informed decisions by outlining what is most important to consider and know about owning an autoclave.