Examine The Backpressure At The Drain Block; Replace The Pump Piston Seals - Hach APA 6000 Maintenance Et Dépannage

1. Make sure that the sample inlet tubing does not have a blockage. If it
does, replace the tubing. Refer to
2. Make sure that the 0.5 µm filter in the sample conditioning block
does not have a blockage. If it does, replace the filter. Refer to
Replace the sample conditioning block filter
clean and reuse the filter.

Examine the backpressure at the drain block

1. Make sure that the maximum pressure reading on the pressure
gauge at the drain block is about 1.4–1.7 bar (20–25 psi). Maximum
pressure occurs when the pump module pushes fluid through the
detector line.
a. If the maximum pressure is less than 1.4–1.7 bar (20–25 psi), the
pump piston seals may have a leak. Replace the pump piston
seals. Refer to

Replace the pump piston seals

b. If the maximum pressure is more than 1.4–1.7 bar (20–25 psi),
the backpressure device has contamination buildup. Replace the
backpressure device as necessary.
2. Make sure that the minimum pressure reading on the pressure
gauge at the drain block is about 0.35–0.7 bar (5–10 psi) less than
the maximum.
If the pressure gauge reads 2 bar (20 psi) while the pump module is
operating, then decreases to below 0.35 bar (5 psi) after the pump
stops, the rotary valve may have a leak. Examine the rotary valve
and tubing for leaks.
Replace the pump piston seals
N O T I C E
Failure to replace the pump piston seals every 3 months will void the warranty.
Replace the pump piston seals to prevent pump leakage. Pump leakage
can cause the pump piston to get stuck, corrosion of internal parts and
the piston guide to get stuck in the motor housing.
Items to collect:
• Wrench, open-end, ¾-in.
Replace a tube on page 14.
on page 13. Do not
on page 7.
• Pump piston seals (2x)
• O-ring, fluorocarbon, 0.676-in. ID x 0.070-in. wide
• Alignment tool for the pump module
1. Put the analyzer in shutdown mode. Refer to
shutdown mode on page 5.
2. Set the power switch to off. The piston will be fully forward.
3. Remove the pump body assembly from the pump module. Refer to
the illustrated steps in Figure
a. Remove the two tubes connected to the pump body assembly.
b. Remove the knurled lock ring from the pump body assembly.
Keep for later use.
c. Gently pull the pump body assembly away from the pump module
base and off the piston. Make sure not to bend the piston and
lead screw assembly.
4. Use a ¾-in. open-end wrench to loosen the ceramic piston guide
from the pump body assembly. Turn the piston guide to remove it.
Keep for later use. Refer to
5. Replace the piston seals. Refer to
a. Remove the two piston seals from the seal retaining ring and
discard. Make sure not to damage the seal retaining ring.
b. Install two new piston seals on the seal retaining ring. Put one
seal flanged-side up and push the seal retaining ring on it. Do the
same for the opposite side. Make sure that both rings are fully
seated and that the exposed edge is flat.
6. If leakage has occurred, replace the O-ring. Refer to
a. Remove the O-ring seated in the assembly. Do not use a sharp
tool to remove the O-ring or pump body damage could occur.
b. Install a new O-ring. Make sure that the O-ring is fully seated in
the groove.
7. Assemble the pump body assembly.
a. Lower the assembled part into the pump body so that it sits on
the O-ring. Refer to Figure
Put the analyzer in
1.
Figure 2.
Figure 2.
Figure
2.
English 7
2.