agilent 1100 pump no flow

[hplcnewuser1]

agilent 1100 pump is turned on, green and pump sounds good. There is no mobile phase flow even after removing the column. Pumping either A or B solvent at 100% and high flow rate there is no flow at all, pressure is always zero. What could be the cause? mp's are water and acn no buffers.
already removed the column and there is still no flow.
any help appreciated.

[tom jupille]

Work backward from the pump. Is the inlet line primed? Disconnect the inlet line at the pump, lift the reservoir(s) and see if the solvent(s) flow by gravity. If they do, then you have a problem (plug?) at the inlet valves. If they don't, then disconnect at the inlet of the degasser and check there, . . . etc.

[Consumer Products Guy]

You're a new user. Prime ALL the lines going to degasser, multichannel gradient valve (or whatever Agilent calls it), lines to the pump. Use a syringe if necessary, pumps are made to pump liquids, not gasses.

If the purge line on the pump is routed through a tube to waste, make sure flow is not going out that. Oh yes, new user: make sure that purge valve is closed when trying to pump.

[hplcnewuser1]

thanks everyone. I am able to narrow it down now. I Turned off the system and when I unscrewed the thin plastic tube, from multichanel mixing valve into the pump, I saw mobile phase flow coming through.

[James_Ball]

thanks everyone. I am able to narrow it down now. I Turned off the system and when I unscrewed the thin plastic tube, from multichanel mixing valve into the pump, I saw mobile phase flow coming through.

That means you have fluid flowing down to the pump. That is good.

Now the problem can be at the Active Inlet valve on the bottom of the pump, the pump seals, or the outlet check valve screwed into the top of the pump.

Attach the thin line to the pump, and remove the waste line coming from the purge valve, turn on the pump at 1ml/min, open the purge valve and use something to pull a suction on the little outlet stem on the purge valve. If you can pull flow through there, then nothing is clogged and the Active inlet valve is opening. If you can't pull any liquid through then possibly the Active Inlet Valve solenoid is not opening or the valve is clogged.

If you can pull liquid through there, attach a column and close the valve slowly. If pressure builds up then it just needed priming. If pressure does not build up then the active inlet valve is not closing. If pressure build but falls again with the rhythm of the pump, then the outlet check valve is not closing and allowing the pressure to flow back into the pump head as the piston returns.

[vmu]

If pressure build but falls again with the rhythm of the pump, then the outlet check valve is not closing

The same is true for the inlet valve, and the inlet valve fails more frequently than the outlet valve. There is a simple test for a leaky inlet valve. When the pump is delivering mobile phase to the system from one channel and the pressure is intensively pulsating, as described above, allow an elongated air bubble (ca. 5-10 mm in length; not just tiny spherical bubble) to enter the inlet line. Then see how the bubble is moving along the tube. If the forward movements of the bubble are alternating with periodic stops (in the rhythm of the pump), the inlet valve is OK. If the forward movements of the bubble are alternating with more or less slow backward movements, the inlet valve is not closing properly.