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HTEC-500
B. Remove Air from Tubing Going to the Column
If these above steps don’t work, another cause of this problem could be that an air bubble(s) may
be trapped in the tubing between the pump and the (pre)column. To solve this, disconnect the
tubing upstream of the precolumn and pump mobile phase through until the air bubble(s) comes
out.
C. Wash the Pump
If the problem still persists, methanol is also effective in solving this problem. A contaminated inner
surface will trap air easier than a clean surface. This problem may happen when you do not use any
organic solution in the mobile phase. In some cases, a methanol wash may not work. If you use
more than a few percent of methanol in the mobile phase, please skip to the section on Error 3 in
chapter 8-3, page 13.
1) First, disconnect the columns from the line to prevent methanol from flowing through them.
When you remove any column, plug the inlet and outlet of the column as soon as possible. Also
plug the free end of the tubing which was connected to the precolumn or column to prevent air
coming in when you aspirate the solution from the pump drain valve.
2) Turn off the pump and replace the mobile phase with ultrapure water. Then open the purge
valve and aspirate the ultrapure water as it comes into the pump.
3) Run the pump and then close the valve. The plug on the free end of the tubing will pop out. The
pump needs to run for a few minutes to wash out the mobile phase from the tubing after the
pump. When aspirating from the purge drain using a syringe, the disconnected tubing, which
was connected to the column, must be plugged or air will be introduced through the aspiration
of solution from the drain valve by the syringe.
4) Now, you can stop the pump, replace the ultrapure water with methanol and repeat the above
procedure. Following this, replace the methanol with ultrapure water and then replace the
ultrapure water with mobile phase.
If these three treatments do not work, (1. Removing air from pump head, 2. Removing air form the
tubing, 3. Methanol wash) there is another possibility that some small dust or lint is trapped in one of
the check valves. Normally, this type of problem happens in the inlet check valve.
8-2.
Types of Pump Errors
When the fluid flow system has some problems, an error message will appear on the LCD screen and
the pump will automatically stop. The types of errors and the main causes are described in chapter 8-3,
next page. When a pump error occurs, a contact closure signal is generated at the pump error out
signal terminal which is located on the right side of the system. If the ‘pump error out’ and ‘a signal in for
the emergency stop’ on your autosampler are connected by using signal cables, the upcoming run to
be processed by the autosampler will be stopped and you can avoid loosing samples after the pump
stops.
Table 1. Types of errors and their cause(s).
Error 3 and 4 only occur when the pulse free mode is on. Error 2 does not exist.
Cause
Current pressure is over the pressure limit setting.
Pressure decreases suddenly or there might be a leak.
Motor torque error
Error
1
3
4
