Determing moisture content in dried milk

Construction

An oven provided with a special air-circulation system and a dry air unit for drying 16 samples.

 

This double walled drying oven is constructed with a stainless steel inner- and outer-cabinet. The space between the inner- and the outer walls is filled with insulation material to reduce the heat exchange to a minimum.

 

The inner-cabinet is closed by a double sealed outer door, the door closes on the inner-cabinet and the outer-cabinet with the use of silicone sealing profiles.

 

The chamber is provided with a ventilator mounted in the back wall for the internal air-circulation. The motor of the ventilator is mounted outside the inner-cabinet and therefore provided with a lengthened axle. The ventilator sucks the air through the inner-cabinet and transports the air via the double side-walls to the front of the cabinet. Because of this unique system a very high temperature uniformity can be achieved, even when the chamber is filled with samples. To refresh the air in the cabinet an exhaust is mounted in top of the cabinet.

 

Internal dimensions: W x D x H: 450 x 400 x 450mm.

Temperature control

The control panel is mounted on the left of the inner-cabinet and provided with  a main-switch, a digital proportional control setting, a safety and digital timer and an acoustic signal.

  

The heating is controlled by a digital adjustable and readable proportional temperature controller in combination with a PT100 1/3 din temperature sensor mounted inside the cabinet. This controls the heating by means of a solid state relays. The accuracy of the controller 0,1°C. Temperature range: 110°C. Temperature stability 0,1°C.

 

The digital timer will start as soon as the set-temperature is reached. After reaching this time an acoustic signal will be activated. The timer can be reset by a switch on the control panel.

 

This switch has 3 options:

  • Off
  • Stand by: the oven is heating till the set-temperature.
  • Timer: the timer will start as soon as the set-temperature is reached.

 

Dry air unit:

As drying dishes, columns of hard polypropylene, are used every column in the metal block in the oven is separately connected to 16 copper tubes.

 

Outside the oven every tube is connected to a restrictor with an inlet pressure of approximately 1,3 bar.

During the drying process, dry air is heated in the oven trough the copper tube and passed through the columns with dried milk. The space above the oven is simple to reach by a lid.

Air supply

For compressed air there is a connection on the backside of the oven. The necessary compressed dry air may have a maximum humidity, similar to a dew-point of –60°C. 

 

The oven is provided with an adjustable pressure-regulator, manometers and a replaceable silica gel  pattern for safety of the humidity of the supplied compressed air. These supplies can be found on the control panel on the right side.

 

Note:

  • The oven has CE mark.
  • Connection 230 Volt.
  • The oven is delivered with user’s-manual and temperature test-rapport and air test-rapport.
  • Delivery including Polycarbonate tube for silica gel, 80PP columns with PE filters, incl. stoppers, PVC stopper container, rod suitable for placing PE filters.
  • Temperature accuracy of the samples < 0,2°C measured in time and place in the environmental air.