129
Valves
Sample Injectors
How to Choose a Sample Injector
Table I below compares the characteristics of Rheodyne
®
manual
sample injectors and will help you choose the most suitable model.
Types and Capabilities
Models ending in 25 (i.e. 7725) are dual mode injectors. Dual mode
injectors can use both the partial-filling and the complete-filling
method for loading the sample loop (See the “Sample Loop Loading”
Application Note on page 131). They are variable volume injectors
because they allow the loading of various sample volumes. These dual
mode injectors, also called front-loading injectors, have a needle port
for loading sample built into the handle. The unique injection port
design allows the tip of the needle to connect directly to the sample
loop for no sample loss during loading.
Models ending in 10 (i.e. 7010) are single mode injectors. Single mode
injectors use only the complete-fllingmethod to load the sample loop.
They are called fxed loop injectors as the sample loop size determines
the sample volume. These injectors require a Loop Filler Port accessory
(page 139), as a needle port is not built into the valve handle. There
is not a direct connection between the syringe and the sample loop.
Therefore, an excess of sample must be used to overfll the Loop Filler
Port and completely fll the sample loop.
Models with an “i” suffx (i.e. 7725i) are identical to the models with the
same numbers but the “i” designates a built-in position sensing switch.
The switch provides the chromatograph with a reproducible start signal
to mark the injection time in the data system.
The reproducibility of manual sample injectors depends on operator
skill, syringe calibration, and the loading method. Partial-flling method
is typically reproducible to 1.0% relative standard deviation (RSD).
Complete-flling method is reproducible to 0.1% RSD for loops 5 µL.
Scale, Sample Volume, and Loop Size
Analytical scale models are for conventional columns with samples
from 1.0 µL to 5.0 mL. Microscale models are for 1.0 mm and 2.0 mm
inner diameter columns. Model 8125 has a sample range of 0.1 µL
to 500 µL, and can be used for both analytical and micro columns.
Preparative scale models are for columns with diameters from 1 to 10
cm, and operate at high fow rates with samples from 100 µL to 20 mL.
Liquid Contact Materials
All models have a polymeric rotor seal of Vespel
®
(pH 0 to 10 tolerance),
ETFE or PEEK
™
(both pH0 to 14). Stators are 316 stainless steel or PEEK.
Most models have an inert ceramic stator face assembly.
Make-Before-Break (MBB
®
)
Models incorporating Rheodyne’s MBB architecture design provide
uninterrupted flow when switching between LOAD and INJECT
positions. MBB greatly reduces transient pressure shocks and is
benefcial for fow-sensitive detectors, fragile columns, and pumps.
Models 7725, 9725, 3725, and “i” versions contain the MBB design.
Replacement Parts
Genuine Rheodyne parts are available for easy maintenance of your
Rheodyne valve. RheBuild
®
Kits offer a complete solution to keep
your valve running, providing all necessary parts to rebuild your valve
and easy to use step by step instructions to assist you in the process.
Rheodyne also offers a complete line of sample loops, fttings, and
accessories designed specifcally for the Rheodyne valve.
Injector Valves
Type & Capabilities
Scale
Partial Filling
Volumes
(Range)
Sample Loop
Sizes (Range) Wetted Materials
Max.
psi (bar)
1
Max.
T (ºC) MBB
2
Model
3
Dual Mode
Can load the loop by two methods:
1) Partial flling – syringe determines volume without wasting sample
2) Complete flling – loop determines volume by over flling loop
Analytical
1 µL – 2.5 mL
1 µL – 5.0 mL
2 µL – 5.0 mL
2 µL – 10 mL
316 SST, Vespel
PEEK, ETFE, ceramic
7,000 (483)
5,000 (340)
80º
50º
Yes
Yes
7725, 7725i
9725, 9725i
Micro
0.1 µL – 500 µL
5 µL – 1.0 mL
316 SST, PEEK, Vespel, ceramic 7,000 (483) 80º No
8125
Preparative 100 µL – 10 mL
2.0 mL – 20 mL 316 SST, PEEK
PEEK
5,000 (340)
4,000 (276)
50º
50º
Yes
Yes
3725(i)-038
3725, 3725i
Single Mode
Can load the loop by one method:
Complete flling – loop determines volume by over flling loop
Analytical Not Applicable
5 µL – 5.0 mL
5 µL – 10 mL
316 SST, Vespel
PEEK, ETFE, Ceramic
7,000 (483)
5,000 (340)
80º
50º
No
No
7000
9010
Micro
Not Applicable
0.5 µL – 5 µL
0.2 µL – 1 µL
316 SST, Vespel
316 SST, Vespel
7,000 (483)
7,000 (483)
80º
80º
No
No
7410
7520
SST = Stainless Steel
1
This is the maximum pressure to which the valve can be adjusted. Some models are shipped from the factory set for lower pressures.
2
MBB (Make-Before-Break) is a design that provides uninterrupted fow when switching between LOAD and INJECT. MBB also greatly reduces transient pressure shocks.
3
Models with an “i” suffx have a built-in position sensing switch. Models 8125 and 9010 also have a built-in switch.
Characteristics of Rheodyne Manual Sample Injectors
FOR ORDERING & DISTRIBUTOR INFORMATION +1 800 426 0191 • +1 360 679 2528 • www.idex-hs.com