Thermo Scientific Accela 1250, Hardware Manual

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6
Troubleshooting
Diagnostic Tests
Thermo Scientific Accela 600 and 1250 Pump Hardware Manual 111
9. If your flow rate is unstable or inaccurate, see Table 13 .
Testing the Residual Pulsatio
n
This test measures the pump pulsation.
 To measure the pump pulsation
1. Connect a 40 bar (~580 psi) restrictor cartridge to the LDA outlet. Align the restrictor so
that the flow is in the direction of the arrow marked on the restrictor (see Figure 108 on
page 110 ).
2. Fill a mobile phase reservoir with HPLC-grade methanol and connect it to inlet
channel A.
3. Open the purge valve.
4. Set the pressure unit to bar.
5. Verify that the pressure is 0.
6. Set channel A to 100%.
7. Set the flow rate to 500 μL/min.
8. Start the pump, wait 1 minute, and then close the purge valve.
9. Wait 5 minutes to allow the pump pressure to equilibrate.
10. Observe the pressure graph for pressure fluctuations. The pressure standard deviation
should be less than 1 bar (14.5 psi).
Table 13. Reasons for unstable flow rates
Possible reason for unstable flow rate Correction
Damaged or dirty check valve Clean the check valves. See “Cleaning the
Check Valves” on page 103 .
Worn out primary piston seals Replace the seals. See “Replacing the Primary
Piston Seals” on page 97 .
Unstable load (column) Use a backpressure restrictor or another
column.
Tip For information on viewing the pump’s status and starting and stopping the
solvent flow from the pump, refer to the data system Help.