Four temperature control applications and one circulation chiller – Part 1
Bath circulators are and indispensable part of modern laboratories, production facilities, and test benches. With their help, samples can be precisely tempered, and consistent quality can be ensured in endurance tests. The respective requirements for the thermostat are highly diverse. In this two-part article, we will show examples of four applications – two examples of internal and two of external applications – and how the versatile LAUDA ECO meets your requirements.
We will start with the two examples of internal temperature control applications. We have selected some from the field of quality control, which involves tests according to specified DIN standards.
This is what makes the ECO so versatile
The ECO series offers a wide temperature range from -50 to 200°C with a heating capacity of 2 or 2.6 kW or a cooling capacity of 300 to 700 W. With different bath volumes (3 to 40L) or purely as an immersion thermostat, with optional pump connections, numerous interfaces, and a large number of accessories (racks, shelves, etc), the ECO can be optimally configured for any application. The intuitive display can also be selected in two variants (gold and silver), depending on requirements.
1) Tempering of specimens: testing of glass according to DIN ISO 719
Bath circulators are used for quality control of samples that must run according to specified standards. An example of this is testing the water resistance of glass grit at 98°C according to DIN ISO 719. This test is important for determining the hydrolytic classes of glass types for pharmaceutical use according to the European Pharmacopoeia. The therm ‘hydrolytic class’ refers to the resistance of a material to hydrolysis, a process in which a substance is cleaved by water. The hydrolytic class is often used to evaluate the suitability of a material for applications where it comes into contact with water. Class 1 is the most resistant, with class 6 being the least.
The ECO line is rated up to a maximum temperature of 200°C. With a heating capacity of up to 2.6 kW, the thermostats can quickly heat the samples to the set temperature of 98°C and reliably hold them there. Another special requirement is that as many glass flasks as possible with a height of 155mm should be tested simultaneously. The ECO E 25 S is particularly suitable for this purpose. Its bath opening is 331mm x 537mm, and the bath depth is 200mm. This means that it can be used to temper particularly large and tall flasks. The Silver version of the display is sufficient in its range of functions since the temperature is to be kept constant and no dynamics are required. In addition, the heating power of 2 kW is sufficient, so there is no need to invest in the higher power class.
The other accessories then ensure optimum adaptation to the test requirements. A height-adjustable shelf is used to prevent the glass flasks from floating up during temperature control. This is equipped with clamps to hold the glass bulbs and is fixed to the edge of the bath so that the complete rack is not pulled out and the tipping over of the remaining samples is prevented when the individual samples are removed (see figure 1).
2) Tempering of samples: Fogging test according to DIN 75201
In the quality control of plastic and elastomer materials, the so-called fogging tests are carried out in accordance with DIN 75201. They are used to test the fogging properties of materials used, for example, in the passenger compartments or automobiles. Fogging occurs when volatile organic compounds outgas from a material and settle on neighbouring surfaces, which can lead to a coating or film.
The standard provides for two test methods. One of them is the gravimetric determination of the condensable components. For this purpose, the sample is placed in a beaker and covered with an aluminium foil disc. The material is heated to 100°C for 16 hours, while the aluminium foil is cooled to 21°C. The sample is then subjected to a temperature test. The semi-volatile organic compound gases released condense on the cooling disc and the amount of mist condensate collected is measured at the end of the 16 hours.
Figures 2 and 3 show an oil bath with eight beakers covered with eight plates externally cooled to 21°C. An ECO immersion thermostat provides the necessary temperature control for the oil bath. Here, too, the Silver version is sufficient to start up the 100°C and keep it constant. The built-in pressure pump, which can be adjusted in 6 stages, ensures uniform flow around the beakers with temperature stability of 0.01K.
Due to the long run time and the associated resource commitment, it is advantageous if the test can be run unattended during quiet periods. The ECO instrument line has numerous safety functions that allow unattended continuous operation so that temperature control can be performed at night and gravimetric measurement can then be performed during the day.
Keep your eyes peeled for Part 2 – coming shortly!
Today, two internal use cases have been presented. The next article will deal with two external applications – one for temperature control of consumers, especially a booster pump in production, and one for temperature control of test benches, in this case, a 4-channel test bench.