Why is purified water needed for glassware washing in laboratories?
Most lab technicians will be aware that purified water is required during final rinsing of dirty and soiled glassware because it removes surface contaminants from the washing process. What is not so widely understood is what kind of water quality or type of purification system should be used. To be able to supply the right feed to the washer it is important to be aware that purification systems can provide different levels of water purity and not all of those levels are suitable for washing glassware.
What is purified water and what kind does a laboratory glassware washer need?
Purified water is water that has been mechanically filtered and processed to remove impurities. There are different grades of water purity. For highly critical laboratory applications such as tissue and cell culturing the highest grade of water purity – Type I ultrapure water – is required. For general chemistry, Type II is specified. And for some uses in the lab, such as glass washing, a lower grade of Type III water can normally be used.
What do I need to produce purified water?
Purified water in the lab is produced by an onsite water purification unit. This is a piece of equipment that uses reverse osmosis and de-ionisation to produce a feed of purified water.
What kind of water purification system do I need to feed a glassware washer?
Some labs simply take a feed to a glass washer from an existing water purification system that supplies another part of the lab and while this solution may seem convenient it may be inadequate and unnecessarily expensive. For example, if the feed is producing Type I ultrapure water the system may be unable to meet the required flow rate demanded by the glass washer; this is because the high volume of water required by the multiple rinse cycles of laboratory glassware washers can quickly exhaust the de-ionisation filters used in systems that produce Type I water for analytical requirements. Type I ultrapure water is not required for glass washers and so placing a high output demand on a Type I system is unnecessarily costly. Worse still, Type I water can cause damage to the washer because at very high temperatures it can corrode the stainless interior. In contrast, medium-purity water systems that produce Type III water can make and store large volumes of water that is suitable for use in glass washers at lower costs than Type I water production systems.
When specifying a water purification system to supply a glass washer there are some good options available that will give you the right level of purity at low cost. You should consider practicalities such as ease of installation, ease of use and footprint, and again there are options that are simple to operate and easy to maintain that don’t take up a lot of valuable space in the lab. For example, the SUEZ Purite PW300 is designed specifically for use with laboratory glassware washing machines. It has a small footprint, an easy-to-use LCD colour touch screen and can provide rinse water to the required purity for glassware washers at a guaranteed production rate of 30 l/hr (at 10 degrees c).
The Purewater 300 is available with or without a feed pump, as some glasswashers can operate on a gravity feed to provide positive pressure feed to the glasswasher, but others need a higher positive pressure as they have no pump internally to draw in the water. Always check with the washer manufacturer if the washer has a feed water draw pump or not.
So, by specifying a water purification system that delivers a reliable volume of water at the right level of purity you can make sure you are saving money and protecting the washer from damage while cleaning the glassware properly every time.