- 1). Check that the solvent inlet filter and outlet valve filter are not clogged. If they are clogged, clean or replace with a new filter. Clogged valves will result in erratic pressure or the pump failing to prime.
- 2). Clean the inlet and outlet valves. Take off the inlet valve and flush it with 50 mL of the solvent used in the HPLC. If the outlet valve does not have a filter, clean it as with the inlet filter. If it does have a filter, replace the valve. Dirty valves can cause erratic pressure or an operating pressure much lower than normal.
- 3). Open the purge valve or the outlet check valve if the pump will not prime. This can be caused by too much back pressure in the pump head.
- 4). Check that there is no air in the pump head or air bubbles throughout the inlet line. Air in these spots will result in erratic pressure. To remove air in the inlet line, degas the solvent and replace the inlet filter. To remove air in the pump head, purge the pump for 30 seconds. Run the pump at 1,000 psi or higher for 30 minutes. This forces the air to dissolve in the solvent.
- 5). Replace the seal on the pump. A worn seal will cause air to leak out, resulting in a low operating pressure or very erratic pressure. When replacing the seal, also inspect the piston. A worn or scratched piston needs to be replaced immediately. Use a magnifying glass, as scratches and other signs of wear may not be visible to the naked eye. Look for any buildup on the piston, as this can cause the seal to wear out very quickly. Salt buildup means the machine is not being cleaned properly at the end of the day. Before shutting down the machine at the end of each day, run distilled water through the pump to remove any salt buildup.
Troubleshooting HPLC Pump
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