instructions

Gradient Mixer GM-1

1. Introduction

The Gradient Mixer GM-1 (120 V, Code No. 19-0495-01,

230V 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.

i56-2853-00 AE, 2002-12 • p1