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i 56-2853-00 AE, 2002-12 • p1
instructions
Gradient Mixer GM-1
1. Introduction
The Gradient Mixer GM-1 (120 V, Code No. 19-0495-01,
230 V Code No. 19-0485-01) consists of two identical
reservoirs mounted on a base plate; connection between the
reservoirs is made via a valve. Mounted above the mixing
reservoir is a motor unit which drives a stirrer blade. The
outlet from the mixing reservoir to the column is fitted with
a flow control valve, FCV-1. The Gradient Mixer is
conveniently supported on a laboratory stand. Capillary
tubing, 2 m, is also supplied.
2. Safety
Warning!
When using hazardous chemicals, all suitable protective
measures such as protective glasses, must be taken.
3. Unpacking
Unpack the equipment carefully and check the contents of
the carton against the packing list.
4. Description
THE BASE PLATE (11)* is a precision machined
polypropylene block on which the reservoir cylinders (7) are
mounted.
Sealing between the base plate and the cylinders is provided
by O-rings (8).
THE RESERVOIR CYLINDERS (7) are straight
polymethylpentene tubes threaded at one end and with air
inlets at the other end. Each cylinder has a capacity of 300 ml
and is graduated to 250 ml at 25 ml intervals to give a rapid
check of the volume of liquid remaining in the reservoirs.
The mixing reservoir carries the motor unit (1, 2) and the
other reservoir is fitted with a snap-on lid (3).
THE MOTOR UNIT (1, 2) consists of a fully encapsulated
low speed 250 or 300 rpm synchronous motor mounted in
polypropylene housing. A phasing condensor ensures that
the direction of stirring is always the same and that the
stirrer blade (6) lifts the liquid entering the mixing reservoir.
The motor unit is supplied for operation from 100–120 or
220–240 V AC, 50 or 60 Hz.
THE STIRRER BLADE (6) is secured to the motor axle by a
nylon screw (5). It is unnecessary to remove the screw to
release the stirrer blade.
THE CONTROL VALVE (12) regulates the flow of liquid
between the two reservoirs. It is fully open when screwed out
one complete revolution from the closed position.
THE FLOW CONTROL VALVE (18) is a needle valve
designed for shut-off as well as flow control. The valve
nipple accepts capillary tubing 1.6–1.9 mm o.d. Eluent flow
is regulated with the large knob (A). The line on this knob
and the markings on the valve housing can be used as a flow
rate guide. The valve can thus be opened to a previously
determined position to obtain a given flow rate. To obtain
reproducible flow rates the valve should always be returned
to the shut position before setting.
THE STAND MOUNT (21) may be used to support the
Gradient Mixer on a laboratory stand. When not required,
it may be removed from the base plate (11) by unscrewing
the retaining knob (20).
5. Installation
Connection of tubing to the flow control valve
1. Cut the tubing cleanly at a 45° angle.
2. Remove the screw cap and slip it over the tubing.
3. Remove the rubber cone with the help of the metal
stopper.
4. Push the tubing through the rubber cone until it projects
about 1 cm.
5. Seat the tubing in the nipple. Slide the cone along the
tubing, into the nipple.
6. Finger tighten the screw cap.
* Numbers refer to the enclosed Spare Parts drawing.