Thermo Scientific EASY-nLC 1200 Troubleshooting And Maintenance Manual page 31

Pressure Sensors
Flow Sensors
Thermo Scientific
The LED panels for the pump module installed in the EASY-nLC 1200 instrument provide
the following status informations.
LED States
Flow sensor for Illuminates blue—the instrument is turned on and the flow sensor is
Pumps A and B connected to the pump.
Not illuminated—the instrument is not turned on or the flow sensor
is not connected to the pump.
Power Illuminates yellow—The instrument power is turned on.
Not illuminated—The instrument power is turned off.
Error Illuminates red—A pump error has occurred.
Not illuminated—The pump is operating properly.
Pumps A, B and S each have a individual pressure sensor connected to them. The pressure
sensors are located between the pump and its associated rotary valve
Using the strain gauge principle to measure pressure accurately, the pressure sensors are
flow-through, zero dead volume devices with a wetted path that contains 1 µL of
swept volume. The pressure sensors for the EASY-nLC 1200 instrument have an operating
range of 0 to 20 000 psi (1379 bar).
The two flow sensors provide feedback control for pumps A and B. The flow sensors are
liquid mass flow meters with a CMOSens™ patented technology. Each flow meter consists of a
length of fused silica capillary, a sensor chip, a heating resistor, and two temperature sensors
(see Figure 6).
Figure 6. Flow sensor schematic
Flow
Sensor chip
Heater
Temperature sensors
Based on CMOSens™ Technology
Principle patented: US Pat. 6 813 944
EASY-nLC 1200 Troubleshooting & Maintenance Guide
1
Introduction
Hardware Components
Tubing
9