Jenway 6715 - Manual (Page 155)

137
Checking the Sipper Pump
After fitting the tubing it is recommended that the following check is performed to ensure the cuvette
fills correctly and that there are no leaks present.
Select Photometrics from the Main Menu. (You do not need to log in for this check).
Select Settings and the icon.
Select Independent from the Operating Mode options.
Press to accept.
The switch on the front of the accessory will illuminate.
Offer up a receptacle of water or coloured solution to the inlet tube. Press the accessory switch
and allow the pump to run, ensuring the cuvette fills correctly and that no leaks are present. If the
operation is satisfactory press the accessory switch again to stop the pump.
Good Practice Guidelines
Sample Size - the cuvette must be filled with solution. If sample volume is limited, the two-stage
uptake cycle can be used, i.e; sufficient sample is taken up to ultimately fill the cuvette, followed by air
during the second part of the uptake cycle. The sample will be drawn into the cuvette and only air will
occupy the tubing dead space leading to the cuvette.
Sample Characteristics – viscous samples may cause high levels of carryover. A simple test going
from a blank to a standard solution and back to a blank, will determine the degree of carryover.
With normal aqueous solutions it should be possible to keep this figure below 1%. If this cannot be
achieved and it is critical to the test, it may be necessary to include a wash cycle between samples.
System Cleaning – at the end of a sample run it is important to leave the system clean. This can
usually be achieved by pumping deionised water through the system. If the nature of the sample is
such that water will not adequately clean the system, other solvents may be used, providing they are
compatible with the components that will be contacted during cleaning, i.e; PTFE, glass and silicon
rubber tubing.
Pump tubing – the tubing has a finite life and will need to be changed when pumping rates decrease
to unacceptable levels, or the walls of the tubing stick together.
note: If left under roller pressure for prolonged periods, the pump tubing may not pump. In such
cases the tubing should be removed from the roller assembly and be reformed by hand. Normal
operation should be restored. This is not a sign of tube wear.
It is recommended that the tubing should be removed if the sipper pump is not being used for a
prolonged period.