Every freeze dryer is a little different, but maintenance procedures include tasks like regular cleaning, calibration, oil changes and functionality checks. We'll go over the details of freeze dryer maintenance, so you can ensure dependable performance and longevity and keep your equipment safe and compliant.
Essential Components of a Freeze Dryer
Freeze dryers, AKA lyophilizers, remove moisture by freezing a material, creating a vacuum and warming it up. This process causes the ice in the material to convert directly to a gas, which the freeze dryer collects and removes. Unsurprisingly, this multi-step process calls for several different systems, each of which must be well-maintained to ensure continued operation.
The major parts of a freeze dryer include the following components:
- Vacuum system: The vacuum system of a lyophilizer includes the vacuum pump, the chamber door and manifold gaskets. Your freeze dryer might start underperforming if these components aren't up to par. From confirming the pressurization capabilities of the vacuum system to checking for valve leaks, the many parts of a vacuum system require maintenance.
- Product and condenser chambers: The main chambers, including shelf surfaces, need frequent and careful cleaning to prevent damage. For example, some cleaners and condensates can damage certain shelving or door materials if not wiped off or neutralized.
- Instrumentation system: A freeze dryer's instrumentation generally includes temperature and pressure sensors, which need regular calibration. Many lyophilizers use T-type thermocouples to measure temperatures for the product, the shelf heat transfer fluid and the condenser temperature. The vacuum sensors can range from a thermal conductivity gauge to a combination of Pirani and capacitance manometer-type gauges.
- Mechanical and refrigeration systems: Most of the maintenance for these systems comes from general functionality tests. If things aren't running smoothly, something might be off and calls for more sleuthing.
- Computer systems: The software running your lyophilizer also needs occasional upkeep. This maintenance is usually as simple as backing up your data files every month so they don't get lost due to technical issues.
How to Maintain a Lab Freeze Dryer
Lab-grade freeze dryer maintenance includes various processes, many of which should be part of a recurring lyophilizer maintenance schedule. You should include others, like regular cleaning, in your standard operating procedures. Below are the primary steps required for freeze dryer maintenance.
1. Conduct Regular Cleaning
Defrost and clean all condensers, chambers and shelving after each run, and have users confirm cleanliness before starting a run.
If your freeze-dry cycle involves acids, you must neutralize the components with pH buffers. If any chemicals were involved, rinse and wipe down all components, but dry them well. Water shouldn't sit on stainless steel, rubber or acrylic surfaces in the freeze dryer.
2. Maintain Your Vacuum Pump
Freeze dryer troubleshooting issues often come from poor vacuum pump maintenance. Most instruments have either a standard rotary vane pump, an oil-sealed pump or a dry-scroll pump.
The rotary vane and oil-sealed pumps require regular oil changes, usually once every 2,000 hours or when the oil becomes cloudy or dark. A dry-scroll pump doesn't use oil, but you must replace the scroll after about 40,000 hours of use.
Some freeze dryers, like those designed for acid- and solvent-based drying, use a combination of a dry-scroll pump and one of the oil-based pumps. Check your manual for more information on your lyophilizer's maintenance schedule.
You may also have an oil mist eliminator if you have an oil-based pump. Replace this component and its filter elements annually.
3. Test the Refrigeration System
Run a functional test on your refrigeration system to detect any issues. Your freeze dryer might have an automatic system test cycle you can easily run. Do this at least annually, or more often for frequent usage.
Another way to test your freeze dryer is with a standard recipe or dry run. After running the standard recipe, record the measured temperatures and pressures and compare them to benchmarks and the data from the last time you performed the dry run.
If you find a problem with the refrigeration system, you may have a failed valve, a refrigerant leak or a failure in the electrical relay system.
4. Calibrate Your Instrumentation
Temperature and pressure sensors need regular calibration. You may need more frequent calibration if you work with sensitive research applications, your facility has a Good Manufacturing Practices certification or you must abide by regulations from the Food and Drug Administration. Either way, sensor calibration should fit into your regular freeze dryer repair schedule.
Thankfully, the process is typically quick. You can use a crushed ice bath to calibrate some sensors to zero or use an electronic calibration method.
Common Mistakes to Avoid in Freeze Dryer Maintenance
When problems appear with freeze dryers, they often occur due to some common maintenance mistakes, such as:
- Overlooking minor issues: Small problems can quickly lead to big ones on a freeze dryer. Always follow up with seemingly minor issues, and call an authorized service technician if necessary.
- Irregular or inconsistent maintenance: If you don't know when or what you're doing to maintain your lyophilizer, you probably aren't doing it correctly. Keep thorough records of your maintenance activities and document everything from cleaning to repairs.
- Improper cleaning practices: Take the time to understand the cleaning requirements for your lyophilizer and your application. For example, always use a neutralizing cleaner to avoid damaging your equipment if you're working with acidic materials. Evaluate everyone's adherence to your cleaning guidelines periodically.
- Overloading or inadequately freezing your materials before drying: Both of these actions can increase the strain on your freeze dryer and contribute to wear and tear. They can increase the vapor load and run your condenser to its limit.
Simplify Maintenance With the Right Freeze Dryer
As technology advances, freeze dryer maintenance has become easier and more efficient. For example, today's models might have automatic functionality tests or oil-free dry scroll compressors. By considering maintenance demands when you purchase your freeze dryer, you can save yourself a lot of time and headaches in the future.
At New Life Scientific, we work with all types of labs and all types of freeze dryers, so our experienced team can help you find the right equipment from our vast selection of used lyophilizers. Used equipment is much more affordable and available right away. We test every piece of equipment we sell and refurbish them if needed, so you can minimize the risk of your new investment.