Types of fluidized sand baths
A fluidized sand bath consists of a loosely packed mass of fine solid particles (aluminium oxide ) through which an upward flow of air is passed. In the fluidized state, the aluminium oxide particles become mobile, and the bath displays many of the properties of a liquid. However, since the bath is composed of tiny, inert aluminium oxide particles, any concerns related to freezing, boiling and evaporation are eliminated.
Heaters inside the bath container radiate heat into the aluminium oxide. Fluidization acts as the stirring mechanism to evenly distribute heat throughout the bath, resulting in excellent thermal stability and uniformity. These advantages make fluidized sand baths a cost-effective and environmentally friendly, safe, and clean alternative to oil, salt, ultrasonic and molten metal baths, ovens, and furnaces.
Types of fluidized bath
The Cole-Parmer® FSB-200 Series of fluidized sand baths can be split into three categories, broadly determined by the applications they are used for:
- Thermal processing – heating and heat treatment of objects
- Thermal calibration – calibration of thermal sensors
- Thermal cleaning – residue burn-off from industrial tooling
Thermal processing
Compact fluidized sand baths
The Cole-Parmer® FSB-200 series compact fluidized sand baths are ideal for heat treatment processes such as stress testing analysis of metals. These simple baths should be used with the appropriate accessory temperature controller (using the chart below) which includes an integrated flowmeter and dual-setpoint programming to improve temperature accuracy and stability.
These models use brown aluminium oxide (alundum) as the heat transfer medium, which is slightly abrasive. For this reason, these baths are not recommended for sensitive applications such as nitinol shape setting.
Accessories for compact fluidized sand baths
Thermal calibration
Cole-Parmer® FSB-200 series precision fluidized sand baths are used in calibration laboratories for thermal calibration of temperature probes—particularly useful for irregularly shaped sensors which cannot be calibrated in metal block calibrators or liquid baths. These baths are also used in materials and component quality control laboratories for thermal testing of sensitive components such as semiconductor devices, wire product testing and with delicate transducers. The baths can also be used as a constant temperature environment for chemical reactions.
Because the fluidized bed is composed of fine dry white alumina , it does not display the surface tension effects of liquid baths and does not wet any objects immersed in it. The basic electrical insulating property of the medium used in the bath is not affected by fluidization, making it possible to conduct electrical measurements on immersed objects such as assembled printed circuit boards.
In addition, the Cole-Parmer® FSB-200 Series Precision Fluidized Sand Baths have become the market’s preferred choice for carrying out shape setting (heat treatment processing) of nitinol arterial stents and platinum tungsten coils in a safe, precisely controlled, and uniform manner.
There are two models available, 12184-03 and 12184-94 . The overall specifications for each model are essentially the same however the 12184-94 has the additional feature of automatic air control which adjusts the air flow automatically depending on the operating temperature. This model is also fitted with a temperature controller which has an RS232 serial interface, enabling the operating temperature to be set and monitored by a remote computer. The accessories are compatible with both models.
Accessories for precision fluidized sand baths
| Description | Item number |
| Steel mesh sample basket with collar | 12184-02 |
| Dust suppression system with chimney MUST BE USED WITH ONE OF THE PROBE HOLDERS | 12184-96 |
| Probe holder for 8 probes: 8mm x 281mm deep REQUIRES DUST SUPPRESSION SYSTEM | 12184-98 |
| Probe holder for 8 probes: 3 mm, 4 mm(x3), 5 mm, 6 mm (x2), 8 mm x 300 mm deep REQUIRES DUST SUPPRESSION SYSTEM | 12184-99 |
| Spare filter for dust suppression system | 12184-97 |
| Air compressor 230VAC, 50Hz, 1500W | 12184-01 |
| Air pressure regulator and filter | 01184-78 |
| Alumina, white aluminium oxide, 55lbs (US and other regions only) | 01184-73 |
The steel mesh sample basket safely holds samples away from the heating elements of the fluidized bath and assists retrieval of items from the bath. The basket contains a collar to reduce alumina spilling from the chamber.
The dust suppression system chimney is combined with one of the Probe Holders to enable the user to seal the fluidized bath, making it suitable for calibration labs where airborne dust must be avoided. Note there is no direct access to the bath when these accessories are fitted.
Thermal cleaning
Cole-Parmer® FSB-200 series industrial fluidized sand baths are used for safe, efficient and cost-effective cleaning of tooling, components, systems and parts (dies, breaker plates, nozzles, tools, tips, spinnerets, extruder screws, manifolds, etc.). These fluidized baths will remove almost all polymers, including plastic, paint, epoxy, rubber and adhesives, as well as other hydrocarbon-based products such as oils, fluids, grease, lubricants and coatings. Parts immersed into this type of fluidized bath are cleaned by the high-temperature environment of fluidized aluminium oxide which degrades plastic to carbon, which then leaves the bath as CO2. This instant heating and minimized quenching results in shorter cleaning times than those of ovens, and when paired with the even and consistent heat of the bath, results in greatly reduced metal fatigue and tool damage.
Like the compact fluidized baths, these models use the non-corrosive brown aluminium oxide as the heat transfer medium, which also helps to polish and dislodge the carbon residues after the plastic is burnt off. The process of cleaning tooling in these baths ensures there is no wear or damage to expensive parts which can often be caused by manual cleaning. Uniform bath temperature also prevents distortion. There are two models available, the 01184-10, which has a capacity of 5 liters and the deeper 01184-20, with a capacity of 12 liters.
Fume extraction is an important consideration in the plastic burn-off process. Both models can be used with the accessory peripheral fume extraction systems to ensure the safe removal of combustion products while maintaining access to the bath.
Accessories for industrial fluidized sand baths
An extraction fan and cyclone are recommended unless a suitable extraction hood or fume extraction system is already in place. Ducting is not supplied, but 100 mm (4”) fireproof metal ducting should be installed to tolerate the high temperatures used in the processes.
The cyclone and collection bin allow aluminium oxide carried over into the exhaust system to be collected and re-used. The cyclone requires no power and is simply connected via ductwork to the extraction fan and extraction collar accessory which fits in the top of the bath. The extraction fan then draws fumes away from the system. Any aluminium oxide carried over is collected in the bin.
Lids help contain the fluidizing medium and retain heat. They are designed to allow airflow into the top of the bath and allow clean air to be drawn into the bath and through the exhaust duct when connected to an extraction system.
Baskets are required for ease of loading and retrieving tooling from the bath. Deep baskets are required when using the extraction collar.
The extraction fan delivers an extraction rate of 250 CFM (425 m³/hr) and effectively draws toxic fumes away from the bath via the ducting.
Summary of fluidized sand baths
The following table summarizes the uses for the Cole-Parmer® FSB-200 Series of fluidized sand baths:
| Applications | Compact fluidized sand baths
01184-00
01184-02
01189-50 | Precision fluidized sand baths
12184-03
12184-94 | Industrial fluidized sand baths
01184-10
01184-20 |
| Heat treatment | ++ | ++ | ++ |
| Thermal calibration | + | ++ | + |
| Shape setting | - | ++ | - |
| Tool cleaning | + | - | ++ |
| Thermal testing | + | ++ | + |
| Heating of chemical reactors | + | ++ | + |
Key: ++ Bath recommended for this application.
+ Bath would be satisfactory for this application with limitations.
– Bath is not suitable for this application.
