Preferred Plunger Stroke Volume; In-Line Vacuum Degasser - Waters Alliance e2695 Operator's Manual

1.2.5

Preferred plunger stroke volume

The separations module's discrete, programmable stroke volumes provide optimal flow delivery
and solvent blending. Nevertheless, you can improve performance for specific applications by
overriding the default (preprogrammed) stroke volume of 130 µL. To do so, you select a preferred
stroke volume of 25 µL, 50 µL, or 100 µL, as shown in the following table. A lower stroke volume
can be more effective with solvents that require additional mixing, like trifluoroacetic acid (TFA)
gradients. This additional mixing, unlike static or dynamic mixing, occurs without added delay
volume.
Table 1–2: Alternate stroke volumes
Flow range (mL/min)
0.050 - 0.530
0.531 - 1.230
1.231 - 3.030
3.031 - 5.000
1.2.6

In-line vacuum degasser

The design of the PerformancePlus in-line vacuum degasser combines a variable speed,
continuously operating vacuum pump with low-internal-volume degasser chambers. The result is
shortened instrument priming and equilibration times, and minimum delay when resuming
operation from an idle state or following a solvent change.
The degasser vacuum pump is designed specially for membrane degassing of HPLC mobile
phases. The continuously running pump provides rapid vacuum pull-down at high speed and
consistent vacuum level at low speed.
1.2.6.1 Degasser considerations
Degassing efficiency is based on the solvent gas load and the length of time that the solvent
remains in its vacuum chamber. Gas removal efficiency decreases as the solvent flow rate
increases because the solvent is in the vacuum chamber for less time. Adopting a normal
analytical flow rate range of 0.000 to 5.000 mL/min, the degasser removes most of the dissolved
gases. Because you can perform dry and wet priming at flow rates greater than 5.000 mL/min, you
must expose the solvents to the degasser vacuum for a short time (after priming) at zero flow rate
(see "Equilibrate solvents in the in-line vacuum degasser" on page
1.2.6.2 Vacuum degasser pressure transducers
Separations modules are equipped with an absolute pressure transducer (APT), which is
unaffected by altitude or barometric changes. The following table lists the attributes of
APT-equipped separations modules.
Table 1–3: Absolute pressure transducer attributes
Item
Units displayed
Sign of displayed unit
Stroke volume (µL)
25
50
100
130
Absolute pressure transducer
kPa, bar, psa
Positive
February 27, 2018, 715003794 Rev. C
Page 25
77).