Hach-Lange SIGMA SD900 Refrigerated Sampler and All Weather Refrigerated Sampler User Manual - Manual (Page 78)

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Maintenance
6.3 Pump maintenance
CAUTION
Pinch hazard. Always disconnect power to the sampler before
opening the pump cover.
The tubing in the peristaltic pump will deteriorate over time from the
action of the rollers against the tubing. Be sure to replace the pump
tubing before it splits to prolong the life of the sampler and prevent
contamination of the work area.
6.3.1 Pump tube life
Pump tube life depends on several factors:
• Distance from sample source. Locate the sampler as close to
the sample source as possible.
• Vertical lift. Minimize the vertical lift as much as possible.
• Intake rinses. Minimize the number of intake rinses prior to
sample collection.
• Sample retries. Minimize the number of sample retries to
successfully collect a sample.
• Sample volumes/duration. Minimize the volume of sample and
maximize the time between samples.
• Constituents in the sample liquid. Grit and other abrasive solids
cause greater wear on the tube when they are squeezed
through the pump rollers.
6.3.2 Pump tube replacement
Important Note: Use of tubing other than that supplied by the
manufacturer may cause excessive wear on mechanical parts
and/or poor pump performance.
Inspect the pump tubing and rollers on a regular basis. Replace the
tubing when deteriorated, at regular intervals or when the
“change tube” message is displayed (
section 4.9.5 on page 63 ).
Prerequisites:
• Pump tubing—pre-cut or bulk (15 ft or 50 ft).
Note: Refer to Section 8 Replacement Parts and Accessories on page 93
for ordering information.
Removal procedure:
1. Turn off the controller power.
2. If using bulk pump tubing, cut a 23.25 inch piece (24.25 inches
for the AWRS) and mark the tube with alignment dots at the
locations shown in
Figure 32 on page 77 .
3. Disconnect the old pump tubing from the liquid sensor and from
the tube fitting on the sampler housing.
4. Loosen the thumbscrew on the pump cover and open
the cover.
5. Pull the tube from the pump tube track while turning the rotor to
remove the old tubing from the pump.