1 Getting started with the Alliance e2695 Separations Module
32 July 29, 2013, 715003794 Rev. B
Normal flow
During normal flow, V1 is open, allowing solvent to flow along two paths:
• 95 percent of the solvent flows through the body of V2, the sample loop
pressure transducer, the sample loop, and needle. The needle is in the
Stream position, and solvent flows out the needle port, through the seal
pack, and out to the column.
• 5 percent of the solvent flows through the restrictor and the seal pack,
and out to the column.
Injection
The injection cycle is performed in three sequential steps:
• Isolating the sample loop from the normal flow – V1, V2, and V3 close,
then V4 opens, the needle wash pump turns on, and the needle moves to
the Seal position. V2 and V3 then open to vent the sample loop pressure
and to equilibrate the loop to atmospheric pressure.
• Sample withdrawal – V3 closes, the needle wash pump turns off, and the
needle extends into the sample vial. The syringe plunger retracts,
drawing the sample from the vial into the sample loop. The sample does
not enter the syringe.
• Sample injection – V2 closes, V3 opens, and the needle moves to the
stream position to pressurize the sample loop. V1 opens, allowing the
solvent to return to the normal flow. The solvent pushes the sample out
of the sample loop, through the needle, and out to the column. The
syringe returns to the home position, expelling drawn solvent to waste,
and V3 closes.
Carousel configuration
Each carousel is identified by color and letter and occupies a unique position
on the carousel carrier. The separations module displays a warning when you
attempt an injection with a carousel in the wrong position (see “Set
configuration parameters” on page 91). You can perform as many as 99
injections per sample vial, and you can offset the depth of the needle in the
vial for small sample volumes, small injection volumes, or to compensate for
variations in vial bottom thickness (see the table titled “Separations module
vials and low volume inserts:” on page 287). Offsets may also be necessary
when you use low-volume inserts in the sample vials.
To Next Page
Loading...
