Rheodyne 7125 Operating instructions

Brand: Rheodyne

Model: 7125

Type: Operating instructions

Operating Instructions for

Model 7125 Syringe Loading

Sample Injector

mobile phase coming out of the needle port

when the valve is turned from INJECT to

LOAD.

Example: 1-mL loop expands 20 uL

upon decompression from 200 bar.

4.2 Warning: When using the Needle Port

Cleaner, empty the syringe slowly to prevent

solvent from squirting back.

4.3 Caution: Use the correct size syringe

needle to prevent damage to the valve.

4.4 Caution: Rinse the valve after using

buffer solutions to prevent crystals from

forming, which can scratch the rotor seal.

5.0 USING PROPER SYRINGES

Use syringes with 0.028-inch O.D. (22

gauge) x 2-inch long needle, without electro

taper, and 90

point style. Using the incorrect

needle size will damage the injector.

6.0 INSTALLATION

a) To mount the valve on a panel, remove

the handle by loosening the two handle set

screws. Use the two 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.

c) Connect the two vent tubes (supplied) to

ports 5 and 6. Place the outlet ends of both at

the same horizontal level as that of the needle

port to avoid siphoning. See Fig. 2.

1.0 DESCRIPTION

Model 7125 is a seven-port sample

injection valve in which the sample is loaded

through a built-in needle port in the front of

the valve.

Fig. 1 shows the flow diagram of the

valve. The six small circles represent the

ports in the valve stator. The two heavy arcs

represent the connecting passages in the

rotor seal. The larger circle represents the

needle port.

The sample loop is loaded in through the

needle port in the LOAD position. Rotation of

the knob, 60°, switches the valve from LOAD

to INJECT. In the INJECT position the

mobile phase flows through the loop.

2.0 SUPPLIED WITH THE VALVE

Supplied with the valve in a separate bag

are fitting sets for tubing connections and the

items shown below. A 20-uL sample loop is

standard with the valve.

Remove the supplied 22 gauge needle from

the needle port before using the valve.

3.0 SPECIFICATIONS

•Maximum temperature is 80°C.

•Valve is set to hold 345 bar (5000 psi). It can

be adjusted to hold up to 483 bar (7000 psi).

•The wetted surfaces are stainless steel,

alumina ceramic, and an inert polymer.

4.0 IMPORTANT SAFETY NOTICES

4.1 Warning: When using sample loops

larger than 100 uL, shield yourself from

d) Connect the pump to port 2 and the

column to port 3. Leave the column discon-

nected from the valve during initial flushing.

7.0 FLUSHING THE INJECTOR

In the INJECT position, flush the needle

port with about 1 mL of mobile phase, using

the needle port cleaner as shown in Fig. 3. At

this time, the pump flushes the loop.

8.0 COMPLETE LOOP LOADING

In complete filling, the volume of sample

injected is set by the volume of the loop (this

includes the valve passages). This method

produces the highest precision.

Overfill the loop with at least two to three

loop volumes of sample. Five to ten loop

volumes will provide even better precision.

An excess of sample is needed because mo-

bile phase near the wall of the loop is dis-

placed slowly, due to the laminar flow pattern

shown in Fig. 4.

To completely fill the loop:

a) See Warning 4.1 and turn to LOAD.

b) Put the syringe into the needle port. You

will feel tightness during the last 2-3 mm of

travel, as the needle passes through the needle

seal and then stops against the stator face.

c) Load the sample.

d) Leave syringe in and turn to INJECT.

LOAD INJECT

9/64 Hex Key

5/64 Hex Key

Needle Port Cleaner

Mounting Screws (2)

Vent Tubes (2)

Figure 1: 7125 Flow Diagram

Correct level

of vent

line ends Height of

needle port

Figure 2: Correct Position of Vent Lines 9.0 PARTIAL LOOP FILLING

If you only have small quantities of sample,

this is the method of choice. In the partial

filling method the volume of sample injected

is set by the syringe. In this method, no more

than half a loop volume of sample is loaded

into the loop. For example, load no more than

10 uL into a 20 uL loop. With larger volumes

some of the sample is lost out vent tube 6. This

is due to the laminar flow effect shown in

Fig. 4: sample flows down the center of the

loop at twice the average speed.

To partially load the loop:

a) In INJECT, use the Needle Port Cleaner

to flush out the needle port with about 1 mL of

mobile phase. This will flush out contamina-

Flow Tube Wall

Mobile PhaseSample

Figure 4: Laminar Flow Effect

Knob of Valve

Figure 3: Use of the Needle Port Cleaner

Needle Guide

CAUTION: To avoid liquid squirting back

at you, discharge syringe slowly.

Needle Port Cleaner

Syringe Barrel

PO BOX 1909, ROHNERT PARK, CA 94927-1909, U.S.A. • PHONE 707-588-2000 • FAX 707-588-2020

tion from the earlier injection. This liquid will

exit out vent tube 5.

b) Follow steps a-d in Section 8.0.

10.0 ADJUSTING FOR HIGHER PRES-

SURE OPERATION/LEAKAGE

The valve has been factory-set to hold 345

bar. If you need operation to a higher pressure

or if there is a leak between stator and stator

ring proceed as follows.

With the system pressurized, back the three

set screws part-way out of the stator. Tighten

each of the three stator screws 1/8 of a turn,

continue to do so until the leak stops and the

valve is holding the pressure you want.

Confirm that the gap between the stator and

stator ring is equal around the valve. After the

leak has stopped tighten the set screws until

they touch the stator ring. Replace the rotor

seal if the leak continues.

NOTE: If the vent tubes from ports 5 and

6 do not have their outlet ends at the same

horizontal level as the needle port, siphoning

can result, which is often misinterpreted as

a leak.

11.0 MAINTENANCE

With normal use the valve will give many

thousands of injections without trouble. The

rotor seal wears with use and is the only part

that needs routine replacement. The main

causes of early failure are:

a) the wrong needle tip can chip the

ceramic stator face which then causes deep

scratching of the rotor seal surface or,

b) abrasive particles in the sample can

scratch the rotor seal surface.

11.1 CHANGING THE ROTOR SEAL

To change the rotor seal (P/N 7125-047)

refer to Fig. 5 and proceed as follows:

a) Remove the three stator screws.

b) Remove the stator, stator face assembly

and stator ring from the body.

c) Pull the rotor seal off the pins.

d) Leave isolation seal and bearing ring in

place. See Section 12.2 for reassembly.

11.2 REASSEMBLY

To reassemble the valve proceed as

follows and refer to Fig. 5:

a) Line up rotor seal as shown in Fig. 6.

The rotor seal slots face the stator.

b) Replace the stator ring so that the two

stop pins enter the mating holes in the body.

The rotor pin must be between the two stop

pins.

c) Put the stator face assembly on the

stator. Line up the small notch in the rim of the

assembly with port 1 of the stator.

d) Mount the stator and stator face

assembly on the valve by pushing it onto the

two pins on the stator ring.

f) Put the three stator screws in place.

Tighten each an equal amount until the screws

are tight. The three set screws will keep the

space even between the stator and stator ring.

11.3 SPARE PARTS

7125-047 Vespel Rotor Seal (standard)

7125-079 Tefzel Rotor Seal (high pH)

12.0 OPERATING SUGGESTIONS AND

TROUBLESHOOTING

12.1 LEAKAGE

If you see liquid between the stator and

stator ring, tighten the pressure adjusting screw

as explained in Section 11.0. Replace the

rotor seal if the leak continues.

12.2 NEEDLE SEAL LEAKAGE

Since the outside diameter of syringe

needles can be different from syringe

tosyringe, the needle seal (Teflon sleeve in the

rotor seal) may not seal correctly around a

needle which is smaller than average. This

will result in a loss of accuracy in loading

the sample.

12.3 USE OF AQUEOUS BUFFERS OR

SALT SOLUTIONS

To prevent the formation of salt crystals in

the valve, flush out the flow passages and the

injection port with water after using salt

solutions.

12.4 USE OF HIGH pH SOLUTIONS

The standard rotor seal is Vespel, a

polyimide with good wear resistance. It

is sensitive to alkaline attack, so avoid

solutions having a pH of 10 or more. Use the

Tefzel rotor seal for alkaline solutions (see

Section 11.3).

12.5 ACCURACY OF SAMPLE LOOPS

Sample loop sizes are not actual values. The

actual volume can differ by up to 10% for a

20-uL loop. There is a greater difference for

smaller loops. Use partial filling if you must

know the actual volume injected.

13.0 WARRANTY

All Rheodyne valves are warranted

against defects in materials and workman-

ship for a period of one year following date

of shipment by Rheodyne. Rheodyne will

repair or replace any Rheodyne product

that fails to conform to the foregoing war-

ranty, at no charge to the customer, provided

that the valve is returned to Rheodyne's

factory, transportation prepaid. The forego-

ing is Rheodyne's sole warranty of its prod-

ucts, and all other warranties, express or

implied, including any implied warranties

of merchantability or fitness for any particu-

lar purpose are hereby disclaimed. Under no

circumstances will Rheodyne be liable for

any consequential or incidental damages

attributable to any Rheodyne valves, even if

Rheodyne has been placed on notice of the

possibility of such damages.

14.0 RETURN OF VALVES

Products may not be returned which are

radioactive or contaminated by infectious

agents, or other materials that may constitute

health hazards to Rheodyne employees.

Figure 5: Model 7125 Exploded View

Notch

Stop Pins

Figure 6: Rotor Seal Orientation (view from stator)

Handle Assembly

Thrust Bearing

Body

Set Screws (3)

Stator Ring

Stop Pins (2)

Rotor Seal

Isolation Seal

(spring loaded)

Bearing Ring

Needle Port Tube

Assembly

Spring Washers (4)

Needle Seal

Stator

Stator Face Assembly

Stator Screws (3)

Rotor Pin

Seal Pins (4)

Needle Guide

Rheodyne 7125 Operating instructions

Brand: Rheodyne

Model: 7125

Type: Operating instructions

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Rheodyne 7125 Operating instructions

Rheodyne 7125 Operating instructions

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