Is my laboratory bath fluid healthy and how do I know when to change it?
If you’re using a laboratory chiller, circulator, water bath, or temperature control unit (TCU), you may have questions about fluid longevity. For example, how do you know when to change your bath fluid, and how long can the fluid last? TCUs and water baths use various bath fluids, so we need to consider the type of fluid and specific operating conditions to address this question.
When to Change the Water in Your Laboratory Bath Tank
Many applications use water as the bath fluid. Water is a convenient choice, but it also presents some challenges. The main concern with water lies with algal and/or bacterial growth. We recommend adding an algaecide or biocide rated for use with stainless steel equipment to prevent unwanted growth and protect your TCU. If you cannot use an algaecide or biocide additive, you’ll need to change the water frequently, making it a part of your SOP (Standard Operating Procedure).
The type of water you use is also important. Hard water can lead to lime buildup in the bath tank and require the addition of a descaling agent. Tap water that’s not too hard works well in many JULABO units. However, you’ll want to avoid distilled or deionized water, which, over time, will pit and damage stainless-steel components. JULABO SemiChill units are the exception as they can incorporate high-purity water as the bath fluid.
When it comes to knowing when to change the water in your bath tank, you’ll want to be sure the bath water is free from bacteria, algae, fungus, lime, or anything that may interfere with your application and equipment performance. A ready supply of tap water makes changing this type of bath fluid convenient, though you may have to change your bath fluid more frequently to maintain its optimal health.
Tip: Keep your bath water clean and change it often. If the water or bath tank doesn’t look clean and clear, you’ll want to change the water and clean the bath tank using the manufacturer’s recommended cleaning process.
When to Change a Glycol/Water Mix in a Laboratory Bath Tank
Using an ethylene glycol or propylene glycol water mix provides an economical fluid mixture that eliminates the growth of algae and bacteria. A glycol/water mix enables operation to -30 ˚C (1:1 ethylene glycol/water). For processes requiring food-safe fluids, food-grade propylene glycol is an excellent choice.
When using a glycol/water mixture as your bath fluid, you’ll want to pay attention to extreme temperatures. Continuous low-temperature and sub-ambient operation can produce atmospheric moisture condensation in the fluid. Condensation increases the percentage of water content and reduces the mixture’s low-temperature capability. Operation at high temperatures (to +80 ˚C for 1:1 ethylene glycol/water) for extended periods can evaporate water, thus increasing the glycol percentage of the mixture. Simple monitoring of the mixture density (like for automotive anti-freeze) and adjusting the ratio by adding water or glycol can bring the solution back to normal. If you do not know the age of the glycol/water mixture in the TCU (temperature control unit), we recommend changing it; otherwise, annual changes will suffice.
Tip: Maintain the proper percentages in your mixture and plan to replace water/glycol fluids annually. Dispose of all used fluid properly according to local, state, and federal hazardous waste guidelines
When to Change Silicone Fluids in a Laboratory Bath Tank
It’s important to remember that water and silicone can’t be mixed without separation; water will form a lower layer (water has a higher density than silicone fluid) at room temperature. If your application requires low or sub-ambient temperatures in an open bath, atmospheric moisture can condense or freeze and accumulate in the silicone fluid. If you see ice in the bath fluid or it looks cloudy, that’s a good indication of atmospheric moisture condensation. If enough ice forms, it can coat the refrigeration coils in the TCU and cause performance problems, including reduced flow and cooling power. We recommend using a condensation trap lid on open bath models to prevent moisture accumulation. Overall, silicone fluids have a long lifecycle and work very well for low-temperature applications if you control ice and moisture accumulation.
High-temperature operations can stress silicone fluids. Continuous operation at peak temperature ranges will eventually cause fluid decomposition. JULABO silicone fluids have a three-month rating when operating at the fluid’s upper-temperature range. For heating applications, we highly recommend regular fluid changes. Fluid decomposition or a fluid crack creates a gel-like substance, forming a thick mess in the TCU, affects fluid lines and the application.
Tip: Place a note on each TCU with the name of the fluid, the fluid operating temperature range, and the date you need to change to fluid.
For Hydrocarbon fluids, follow the same advice as to the silicone fluid guidelines.
Test the Health of Your Laboratory Bath Fluid with JULABO Crystal
If you want to test the health of your bath fluid, try JULABO Crystal. The JULABO Crystal fluid test offers an analysis of your bath fluid and helps protect future problems before they occur. This simple fluid analysis can reveal a lot about your TCU and how it’s operating. For example, certain minerals and elements in your fluid could indicate deteriorating parts or expired fluids. JULABO Crystal checks your fluid’s viscosity, oxidation, water content, and elemental content. JULABO Crystal analysis kits come in three different sizes, allowing you to send 1, 2, or 6 fluid samples for analysis. It also includes a report on your fluid’s health, content, and any potential signs of deterioration in your TCU.
Tip: Annual fluid tests through JULABO Crystal can help predict wear and tear on your JULABO unit.
Summary & Conclusion: What to Know about Laboratory Fluid Health
Proper monitoring and maintenance of TCU fluids will keep your process and TCU running smoothly. JULABO Crystal offers a fluid analysis that can detect the presence of specific elements that could lead to problems.
In addition to routine fluid changes and inspections of your fluid, we also recommend record-keeping on the type of fluid, fluid temperature range, and refill date for each TCU. This information will ensure proper operation and provide other users access to the age of the fluid. Contact your local JULABO account manager if you have any questions about the type of fluid you should be using in your JULABO, how frequently you should change it, or how to start testing your fluids with JULABO Crystal.
