| You are ready to buy a new glass washer for | | | | storage tanks and spare DI-filter cartridges. |
| your lab, but you are unsure what water feed | | | | Another feature that should be considered when |
| system to use? In most cases, except for special | | | | choosing a water purification system is the ease |
| circumstances for very sensitive applications an | | | | of the maintenance. Filter cartridges need to be |
| ASTM Type II reagent grade water source will be | | | | exchanged from time to time, and some systems |
| sufficient for your lab glassware washer. | | | | require a maintenance plan from the |
| ASTM Type II is defined as water that has | | | | manufacturer. Other systems can be serviced |
| greater than 1 MΩ/cm2 resistivity. Lower grades | | | | easily and within a few minutes by the user. |
| are not recommended for most application and | | | | Quick reference guide for choosing a water |
| Type I water rinses (>18 MΩ/cm2 might be | | | | purification system for a lab glassware washer: |
| necessary for especially sensitive application like | | | | The following questions should be answered |
| HPLC and mass spectrometry. While there are | | | | before choosing a water purification system. |
| several different ways for water purification like | | | | What water quality do I need? Water quality |
| filtration, different kind of filtration, sterilization by | | | | needs are based on the applications for which the |
| UV radiation, adsorption by activated charcoal, to | | | | glassware will be used. Most application will require |
| achieve the resistivity required for lab-grade | | | | ASTM Type II water with a resistivity of >1 MΩ |
| water, the water need either to be distilled or | | | | cm2 |
| deionized. The most commonly used method | | | | What water flow capacity is needed? Some small |
| today is deionization. | | | | glassware washers have a low flow requirement |
| This process uses two ion exchange resins over | | | | and might be able to be fed by a low flow water |
| which the water flows. One resin exchanges | | | | purification system that can be more affordable |
| cationic contaminants for an H+ and the other | | | | alternative. |
| exchanges anionic contaminants for a OHion. Both | | | | How much maintenance am I willing to do myself? |
| resins can be mixed together in one container. | | | | Service contract for routine maintenance and |
| The quality of the water depends on the lengths | | | | cartridge exchanges can offer peace of mind, but |
| of the exchange column and the quality of the | | | | doing cartridge exchanges yourself might be more |
| resin. The resin has to be replaced from time to | | | | cost efficient alternative that has potentially the |
| time. | | | | additional advantage of reducing downtime of the |
| One main feature you need to be aware of when | | | | system. |
| choosing a lab water purification system for your | | | | Is a point-of service DI-water source needed |
| lab glassware washer is the water use of the | | | | additionally to the glass washer feed? Is the |
| washer. If you do not require a large cleaning | | | | water purification only meant to provide a source |
| capacity and you are looking for washer with a | | | | of the DI-water feed for the glassware washer, |
| small footprint like e.g. the 24” Miele G789, the | | | | or is the possibility to obtain water for other |
| Labconco undercounter FlaskScrubbers, the | | | | applications also required? Some water purification |
| Lancer LX, or the untercounter washers from | | | | systems will include a point-of service access to |
| Hotpack, a low flow water system might be the | | | | the DI-water. Frequently asked questions |
| right solution for you. Low flow glass washers | | | | What is ASTM Type I and Type II water? The |
| with DI-water requirements for up to 6 liters/min | | | | American Society for Testing and Material |
| can use low-flow water systems that might be a | | | | (ASTM) sets standard for the amount of ionic |
| much more affordable alternative to a | | | | contamination in lab-grade water. ASTM type I |
| high-throughput-system. Most lab glass washer, | | | | water has the highest purity and a resistivity of |
| however, require a larger water flow, and high | | | | >18 MΩ/cm2, which corresponds to an ionic |
| flow system with flow capacities of 15-40 l/min | | | | contamination of less than 1ppb. ASTM Type II |
| will be able to fill the need. Some lab water | | | | water has a resistivity of >1 MΩ/cm2 or less |
| purification system comes with pressurized | | | | than 500ppb total ionic contaminants. |