Waters 1500-Series, Operator'S Manual

Page: 113 / 188

Performing pump diagnostic tests 5-5
• If there is a bad outlet check valve, pressure can possibly increase,
and then immediately decrease as the plunger recedes.
• If the pressure does not rise to the high-pressure limit, try
repriming the pump or increasing the flow rate parameter setting.
9. Allow the pump to reach the high-pressure limit. The pump should stop
flow automatically.
10. After two minutes, record the pressure (P1). One minute later, record
the pressure again (P2).
Calculate head pressure decay with the formula (P1 – P2)/P1. Verify
that head pressure decay is 0.15 or less. If the pressure decay for the
pump head is greater than 0.15, you can possibly have one or more
faulty check valves. Remove and clean or replace the inlet and outlet
check valves (see page 5-14 ).
11. Relieve head pressure by slowly turning the reference valve knob 1/2
turn to the left (for the 1525µ, position the vent valve to the system).
12. Disconnect the right-hand pump head outlet tubing from the draw-off
valve.
13. Transfer the compression plug from the left-hand port of the draw-off
valve to the right-hand one.
14. Reconnect the left-hand pump head outlet tubing to the left-hand port of
the draw-off valve.
15. Repeat step 5 through step 12 to test the left-hand pump head.
16. Remove the compression plugs from the draw-off valve and the tee.
Reconnect the right pump head outlet tubing. Reconnect the tubing from
the pulse dampener.
17. For binary-type pumps, repeat step 3 through step 14 on Pump B, in
step 3 , disconnecting Pump A from the tee.
18. Remove the compression plug from the reference valve (or vent valve)
and reconnect the outlet tube to the system.
19. When you finish, purge the pump with eluent (see Chapter 4 ). Direct the
eluent to system by turning the reference valve to the left (for the 1525µ,
position the vent valve to the system).