Maintenanc e
93
Checking and replacing the sample pipes
Warning!
Do not allow dispersant or sample to come into contact with the skin. Some dis-
persants and samples may cause injury.
Caution!
When the pipes are changed do not allow any dispersant or sample to come
into contact with the system covers. Some samples can cause permanent dam-
age to the surfaces.
If organic solvents are regularly used as dispersants, the flexible pipes that connect the dis-
persion unit to the wet cell may become hard and discolored. When the sample pipes lose
their elasticity, air will leak into the system at the connections to the sample unit and cell.
The resultant bubbles that then enter the system cause instability in the backgrounds and
sample measurements.
When pipes harden, any movement of a dispersion unit relative to the optical unit may
cause the pipes to become detached.
To change the pipes:
1. Make sure that the dispersion unit, wet cell and pipes are fully drained; and then
remove.
2. Push the new pipes onto the pipe boss to a minimum of 7 mm.
3. Then secure, where fitted, with the aluminum pipe connectors
The sample pipe originally supplied by Malvern is Tygon available from Cole-Parmer Instru-
ment Company. Tygon is chemically compatible with a wide range of materials. Contact
the manufacturer for full information on compatibility.
To retain chemical compatibility:
l Always replace the sample pipes with pipes of the same or better grade.
l Always check the compatibility of new pipes with the samples to be used on the
system. Refer to Hydro EV on page109 of this manual.
The specification of the sample pipes supplied with the dispersion unit is:
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