Operator`s manual

Sentry 2.0 Controls VirTis BenchTop 2K, 4K and 6K

18 Revision 004, 12/09

Interstage Control

If your unit is equipped with a cascade refrigeration system, you can control the

operation of the second compressor from the Interstage Control screen. A cascade

system is a safety feature used to protect the refrigeration system from overloading.

∧ Interstage Control

Interstage ON

ON –12 DIFF 025

Current Temp 1.3 °C

If the Interstage Control is set to ON, the COND or AUTO buttons will activate the

high-stage compressor. The Interstage Control’s Current Temp is monitored until the

Interstage ON temperature is reached. Once the Interstage ON temperature is

reached, the low-stage compressor is activated.

The DIFF temperature is used to prevent overloading of the high-stage compressor. If

the Current Temp exceeds the sum of the Interstage ON temperature and the DIFF

value, the low-stage compressor is deactivated. It will reactivate when the Current

Temp recovers.

Calibration

The Calibration screen allows modification and control of condenser temperature and

vacuum settings. The following procedures require removal of the electrical box cover

under the unit’s right-side panel.

CAUTION! REMOVAL OF THE ELECTRICAL BOX EXPOSES HIGH-VOLTAGE COMPONENTS.

USE EXTREME CAUTION AND FOLLOW ELECTRICAL SAFETY PRACTICES.

∧ Calibration

Temperature Span 070

Temperature Zero 14.5C 128

Vacuum 760 Torr 128

Condenser Temperature Calibration

To calibrate the condenser temperature, connect a thermocouple temperature

simulator to the condenser temperature input. Set the simulator temperature to 25 °C.

The current temperature is displayed on the Calibration screen. Adjust the numerical

value of the Temperature Zero as appropriate and press MENU to enter the value.

Upon proper adjustment of the Temperature Zero, change the temperature simulator

value to -60 °C. Adjust the Temperature Span value so that the temperature displayed

equals the calibrator set value. Recheck the value at 25 °C and repeat adjustment if

necessary. Check calibration at desired temperature intervals for verification.