Rheodyne 8125 Operating Instructions

1.0 DESCRIPTION

Model 8125 is a six-port micro-scale
sample injector with a built-in needle port in
the handle for sample loading. Model 8126 is
the pneumatic version. The actuator of
Model 8126 is built around the injector and
allows both manual and automatic operation.
Five of the stator ports have a dual-size port
design and accommodate both 0.5 mm
(0.020") and 1/16" OD tubing. Port 3 only
accommodates 1/16" OD tubing and allows
the tubing to bottom out in the port for low
dispersion connections.

2.0 SUPPLIED WITH THE VALVE

Supplied with the valve in a separate bag
®
are RheFlex Stainless Steel fitting sets for
all ports and the following items. A 5 µL
sample loop comes standard with the valve.
• Hex Keys
• Wrench
• Needle Port Cleaner
• Vent Tubes
• Mounting Screws
• Needle Adapter Assembly
(Model 8126 only)
The #22 gauge needle supplied in the valve
should be removed from the needle port
before using the valve.

3.0 SPECIFICATIONS

• Maximum Operating Pressure: 48 MPa
(483 bar, 7000 psi)
• Maximum Operating Temperature:
Model 8125 - 80°C
Model 8126 - 50°C
• Flow Passage Diameters: 0.3 mm
(0.013") and 0.3 mm (0.012")
• Wetted Surfaces: stainless steel and an
inert polymer
• Gas Supply for Pneumatic Actuator: 0.4
MPa (4.1 bar, 60 psi) to 0.7 MPa (6.9 bar,
100 psi)
• Built-in position sensing switch

4.0 IMPORTANT SAFETY NOTICES

4.1 Warning: When using sample loops
larger than 100 µL, shield yourself from
mobile phase coming out of the needle port
when the valve is turned from INJECT to
LOAD. Example, 1 mL loop ejects 20 µL
upon decompression from 19 MPa (200 bar,
2898 psi).
Rheodyne LLC • A Unit of IDEX Corporation • 600 Park Court, Rohnert Park, CA 94928 • (707) 588-2000 • Fax (707) 588-2020
Operating Instructions
Models 8125 and 8126
Manual and Pneumatic Micro-Scale Sample Injectors
Pump
Position A (LOAD)
Fig. 1. Flow diagram of Models 8125 and 8126.
4.2 Warning: When using the Needle Port
Cleaner, empty the syringe slowly to prevent
solvent from squirting back at you.
4.3 Caution: Rinse the valve after using
buffer solutions to prevent crystals from
forming, which can cause damage to the
rotor seal and stator face assembly.
5.0 USING PROPER NEEDLES AND
TUBING SIZES
5.1 SYRINGE NEEDLES
Use syringes with #22 gauge needles
without electrotaper and 90° (square cut)
point style. The wrong needle tip can cause
damage to the valve.
5.2 TUBING SIZES
Figure 2A shows how 0.5 mm (0.020") and
1/16" OD tubing can connect to five of the
valve ports in Models 8125 and 8126. For
low dispersion, use the 0.5 mm (0.020") OD
tubing for the sample loop. Since Port 3 is
positioned differently in the stator and the
internal geometry allows 1/16" OD tubing to
bottom out in the port, no cavity forms in the
stator port (see Figure 2B). Using 1/16" OD
tubing for the column connection will not
increase dispersion.
1/16" OD tubing can be used in the pump
port and the vent line ports. 1/16" OD tubing
can also be used for sample loops when
using sample volumes larger than 50 µL.
There is a negligible effect on overall
dispersion for these sample sizes.

6.0 INSTALLATION

a) To mount the valve on a panel, remove
the handle by loosening the two handle set
screws. Use the two set screws supplied to
fasten the valve to a panel.
b) Replace the handle by tightening the two
set screws on the two flats of the shaft.
www.rheodyne.com
ste
Waste
4 Need e Port
Pum
Sample Loop
Column u u u u u u u u u u u u
Position B (INJECT)
0.5 mm Ferrule
Cavity Volume = 1.9 µL
1/16" Ferrule
Fig. 2A. Dual-size port design of five of the
stator ports.
Fig. 2B. Port 3 design.
c) Connect the two vent tubes supplied to
Ports 5 and 6. The outlet ends of both vent
tubes should be at the same horizontal level
as that of the needle port to avoid siphoning.
d) Connect the pump to Port 2 and the
column to Port 3. Leave the column
disconnected from the valve during initial
flushing.
eed e Port
le Loop
Column olum
0.020" OD
1/16" OD
1/16" OD
1/16" Ferrule
#7010-010
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