Thermo Scientific 074114, Operator'S Manual

Page: 64 / 148

Dionex PDA Operator’s Manual
56
Doc. 065378-01 1/12
Without the column, backpressure is usually less than 0.34 MPa (50 psi),
depending on the flow rate and tubing ID. Note that the semi-micro flow
cell will develop approximately 1.03 MPa (150 psi) backpressure at
1.0 mL/min.
If the backpressure remains high, remove the fittings and tubing from part
of the flow path, section by section; starting at the waste line, work back
“upstream” until you identify the section causing the substantial
backpressure. Replace tubing and fittings as necessary.
•
Periodically check the flow cell tubing connections for leaks or restrictions.
Replace tubing and fittings as necessary.
•
Periodically repassivate stainless steel systems. This is especially important
when operating with extreme pH levels (which will shorten the life of the
passivation finish) or after a major disassembly. For instructions, see
Passivation of Stainless Steel Systems and Components (Document No.
031152).
•
Monitor baseline noise. If the noise increases above an acceptable level,
especially after a lamp(s) has been in service for an extended length of time,
replace the lamp.
To check the lamp lifetime:
1. Open the Chromeleon 7 Command window (see page 31 ) or the
Chromeleon 6.8 Commands dialog box (see page 32 ).
2. Select UV , and then select UVLampAge and VisLampAge . If a lamp has
been in service for more than 2000 hours, replace it. See Section 5.7 or
Section 5.8 for instructions on replacing the deuterium lamp or tungsten
lamp, respectively.
•
Check the deuterium lamp intensity approximately every 6 months:
1. Open the Chromeleon 7 Command window (see page 31 ) or the
Chromeleon 6.8 Commands dialog box (see page 32 ).
2. Select UV , and then select LampIntensity . The reading should be above
10 million counts for a standard or semi-preparative cell or above 3
million counts for a semi-micro cell.
3. If the lamp intensity reading is too low, calibrate the intensity: In the
Command window or Commands dialog box, select UV_Calibration ,
select Intensity, and execute the command.