The Application:
The thermal requirements on motor oils in particular have risen considerably over the last few years. This consequently means that the testing of these motor oils and lubricants has nowadays become more important for reasons of quality control and operating safety.

Evaporation losses at high temperatures generally lead to an increase in the oil consumption and additionally cause a detrimental change in the lubrication properties of the oils.

The Test Method
The test method is standardized in DIN 51581, CEC L-40-A-93 and ASTM D 5800. The oil sample is heated in a testing device, the evaporation crucible, and subsequently re tained at the testing temperature for exactly 60 minutes. Whilst the testing temperatures can generally be as high as 400°C, motor oils are usually tested at 250°C ±0.5°C

. A constant flow of air, brought about by a differential pressure, extracts the resultant oil vapours. The airflow is accurately regulated by the integrated digital pressure controller. It can be read-off using an inclined manometer.
According to CEC specifications, the partial pressure should be equal to 20 mm water column( 1.96 mbar).

The evaporation crucible with the oil sample is weighed before and after the heating process. The evaporation loss is then calculated from the resultant weight difference and is expressed in percentage by mass.

The Technology
The temperature control of the evaporation tester VP250 is carried out by a PID microprocessor controller. This control technique results in high level of reproducibility and repeatability of the test results. The limits quoted in DIN
51581, ASTM D5800/a and CEC L-40-A-93 can be easily observed with large safety margins.

Features

• Vacuum pump with oil filter
• Port to document the temperature and pressure course
• Microprocessor-controlled temperature control unit
  ⇒ high control accuracy
  ⇒ automatic adaptation of the control parameters
• Wide temperature range from 150 to 300°C
• ⇒ also suitable for special lubricants (gear lubricant oil)
• PT100 probe calibrated against gauged mercury thermometer with 0.1°C scale
  ⇒ deviation to real temperature is smaller than 0.5°C
• Excess temperature protection
• LCD display for actualt temperature / pressure and test time
• Timer with acoustic signal
  ⇒ no separate stopwatch required
• Faults are displayed acoustically and visually
  ⇒ no measurement errors
• Automatic sensor adjustment;
  ⇒ no long-term drift
• Equipped with differential pressure controller to control auto matically differential pressure;
  Standard set pressure: 20 mm H2O; long-term stabi lised pressure sensor; tolerance extent ± 1%;
  Vacuum pump with air filter.

Accessories
The following accessories are available:

• Glassware set consisting of two 2 litre Woulf bottles, glass delivery tubes and silicon hoses.
• Stable supporting unit including an inclined tube manometer 0-30 mm H2O
  ⇒ provide correct positioning of glass bottles
  ⇒ reading and manually controlling of pressure
• Two officially gauged thermometers and a thermo meter holder
• Reference oil for testing the system
• Balance, range 2000 g; accuracy 0.01g
• Cooling unit for cooling down the evaporation crucible after the test
  ⇒ increases reproducibility
  ⇒ provides safe cooling down method as
• ⇒ awkward splashing of water is thus avoided

Technical Specifications

• Mains Connection 230V 110V (selectable)±10% 50/60 Hz, 1300 VA
• Heating power 950 VA at 250°C
• Pressure range: up to 21 mmWS
• Accuracy: ± 0,2°C / ± 0,02 mmWS
• Temperature Range 150.0°C to 300.0°C
• Temperature Display LCD, resolution 0.1°C
• Temperature Setting menu controlled,
• Time Displays, • for test time
• Separate Timer 60 min. countdown display can be called up
• Type of Control digital PID-control
• Control Accuracy ±0.1°C at 250°C
• Temperature Sensors Pt100 (display / control)
• Port: TTL
• Excess Temperature independent safety circuit Protection with separate sensor, Warning Signal acoustic
  Alarm Signal for excess temperature: for faults: acoustic and shown on display
• Dimensions, WxHxD 278x316x300 mm
• Weight (net/gross) 18 kg / 23 kg

Standard Equipment
Vacuum pump; evaporation crucible; tools, test balls, nozzle cleaner; crucible holder, cleaning brush, protective gloves;
300g Wood metal