Firma:              IKA

Modell:            RW 20

Kommentar:   Dokumente engl.

Correct use

Stirrers in the RW20.n series are suitable for stirring and mixing Iiquids with Iow or high viscosity. They are designed for use in the laboratory. For correct use the machine must be fixed to a stand.

Useful facts

In buying this machine you have chosen a high quality product. Ease of use is guaranteed with its handy shape and simple ope­ration. ration. The housing offers protection against ingress of liquids. The materials used and their precise identification make recycling possible and simple, and enables re-use of the parts. The speed can be infinitely adjusted between 60 and 2000 rpm 50 Hz; • 72 and 2400 rpm 60Hz. The machine can be operated continuously and warms up during operation. The generously proportioned cooling surfaces enable distribution and transference of heat to be as even as possible. The two metre Ion mains lead makes it possible to work on stands - even with high glass apparatus under vapour extraction hoods - without extension leads. The precision stirrer shaft is designed as a hollow shaft to allow the stirrer shanks to be inserted.

Drive

The method of operation of the motor is characteristic of the operating behavior of the RW 20.n series units. The motor can be infinitely adjusted via a friction wheel drive unit but is operated in one position only. The power output, rotational speed and torque of the motor are regarded as constant and are optimized for this operating After the friction wheel drive the motor power position. output is transmitted to the off-drive shaft of the stirrer via either the first or second stage of the subsequent manually adjustable toothed gear train.

Neglecting all Iosses, the power at the off-drive shaft during power transmission (conversion) is always as great as the power output of the motor. The gear train merely provides rpm and torque conversion, which can be described in purely theoretical terms by the characteristic curve plotted in.

Friction wheel wear is kept Iow by a helical clutch matched to the gear train. The down-pressure required at the friction wheel is adjusted by the helical clutch according to the moment acting on the stirrer shaft. A Iow torque results in a Iow down-pressure; a high torque results in a high down-pressure.

In order to be able to process high-viscosity media, the RW 20 DZM.n P4 does not have the second switchable reduction stage, but features instead a planetary gear train with a gear ratio of 3.7 1 immediately after the first toothed gear stage. This provides a speed range of 16 to 135 rpm at 50 Hz and 20 to 160 rpm at 60 Hz.

Gear Speed Change

RW 20.n and RW 20 DZM.n only

Should it be necessary to change the gear speed in ,the course of setting up an experiment or process with glass apparatus, then attention must be paid to the movement of the stirrer attachment by the eccentric bearing bush and to the movement in the axial direction. If this is unacceptable, the stirrer attachment must be loosened in the chuck.

Turning (Counter-clockwise) the bearing bush at the black knurled surface over the chuck disengages the gears. The center axis of the stirrer attachment shifts 2.2mm in the radial direction. The bearing bush is then moved 5.5mm up or down in the axial direction according to the range to be set. Turning back (clockwise) the bearing bush re-engages the gears and swings the center axis of the stirrer attachment back to its original position.

Motor Circuit Breaker

The ball race capacitor motor, protected to IP 42, is maintenance­free. In its winding it carries a special overheating circuit breaker (self-locking temperature limiter) which shuts down the motor permanently if the permissible motor temperature is exceeded.

This special type of circuit breaker is used when the automatic reactivation of the protected unit after overheating is undesirable or impermissible. The principle of the temperature limiter is that of a switch that heats up and isolates the motor from the Power supply when the maximum permissible temperature is reached.

When the self-locking temperature sensor is tripped, the yellow glow lamp (B) on the front plate of the unit lights up to indicate the motor overload and the stoppage of the motor. In this case the unit can only be switched back on after it has been switched off for approx. 4-5 minutes by pressing the rocker switch (A) on the front plate or by disconnecting the mains plug.

After this short cooling period, the contacts in the current circuit are closed again and the unit is operational once more.

Speed Display

The rotation speed is adjusted with the rotary knob (C) on the front plate of all RW 20.n stirrer units.

RW 20.n In the RW 20.n unit, a defined rotational speed is set via the scaling of the rotary knob position. The plate (Fig. 5) attached to the side of the unit lists the speeds attained at the set scale values. (The values apply only when Iow Ioads are acting on the stirrer shaft.)

RW 20 DZM.n In the RW 20 DZM.n unit, the rotational speed is displayed directly in revolutions per minute (rpm) on the LCD display (D). The display can only Show speeds up to max. 1999 rpm, which means that the off-drive shaft may be moving at a faster speed than displayed when there are Iow Ioads acting on the stirrer shaft.

RW 20 DZM.n P4 In the RW 20 DZM.n P4 unit, the rotational speed is displayed directly by the LCD display (D), as in the RW 20 DZM.n. As the toothed gear train is no longer adjustable and is set to the lowest speed, the entire rpm range can be displayed.

Commissioning

For correct use, the stirrer machine must be fixed with a cross sleeve (eg R181) to a stable stand (eg R1822). The stirrer container should always be fixed with a tensioner for safety reasons.

Output shaft

lf the unit has not been used for some time, a knocking noise will be heard when switching on, which is due to the preload on the friction lining of the friction wheel drive. This has no detrimental effect on the function of the unit, and the knocking noise will disappear after a short running-in period.

The chuck and off-drive shaft allow stirrer attachments with shank diameters of up to 10mm to be clamped and inserted (except RW20DZM.n P4). The opening at the top of the housing allows stirrer attachments to be pushed up above the top edge of the housing, e.g. in order to change the stirring bowl with the unit switched off.

Accessories

RW 20.n and RW 20 DZM.n

R 1823 Plate stand                             RH 1 Tensioner

R 181 Cross sleeve                            FK(1 Flexible coupling

R 182 Cross sleeve

RW 20 DZM.n P4

R 2723 Telescopic stand                   RH 2 Tensioner

R 261 Cross sleeve                            R 263 Bowl clamp

R 271 Cross sleeve

Associated standars and regulations

Associated EU guidelines

EMV guidelines: 89/336/EC

Machine guidelines: 89/392/EC

Construction in accordance with the following safety Standards:

EN 61 010-1 /VDE 411-1        EN 60 204-1

EN 50 081                               EN 292-1, -2

EN 50 082-1                            EN 414

EN 55 011                               IEC 1010-1

EN 55 014-1                            UL 3101-1

EN 60 555-2, -3                       CAWCSA C22,2 (1010-1)

Technical data

Speed range

(RW20.n 1 RW20 DZM.n)

( 50Hz stage 1)                       min ^-1                  60 - 500

( 50Hz stage II )                       min ^-1                  240 - 2000

( 60Hz stage 1 )                      min ^-1                72 - 600

( 60Hz stage Ii )                       min ^-1                288 - 2400

(RW20 DZM.n P4)

( 50Hz stage 1 )                      min ^-1                16 - 135

( 50Hz stage II )                       min ^-1                  20. 160

Max torque stirrer shaft

(RW20.n 1 RW20 DZM.n)     Ncm                 185

(RW20 DZM.n P4)                  Ncm                 700

Permitted on-time:                  %                     100

Speed adjustment:                  Toggle knob

Speed display:            

(RW20.n)                                                        Scale on front plate of unit

(RW20 DZM.n and RW20 DZM.n P4)           LCD display

Measurement fault:                 max. ±0,5%    ±30 Digit

Nominal voltage:                     VAC                 230±10%

                                               VAC                 115±10%

Frequency:                              Hz                    50 EURO

                                               Hz                    60 USA

Input power:                            W                     72 EURO

                                               W                     87 USA

Power output: (short term)     W                     35

(constant operation)                W         20 +35%

Overall efficiency:                   %          40

Protection type to DIN 40 050:            IP 20

Exess voltage category:                     II

Contamination level:                           2

Protection at overloaded:        Temperature sensor in motor winding

Fuse (on mains plate):            A           4 T (IKA ident.no. 25 85100)

Ambient temperature:                         °C         +5 to +40

Ambient humidity: (rel.)           %          80

Operating position:

on stand, clamping chuck pointing down

Drive:                                       Rib-cooled capacitor motor wich friction wheel drive and subsequent 2-stage toothed gear train.

(RW 20 DZM.n P4 fixed at stage 1; planetary gear train i=3.7:1)

Maximum stirring quantity - water:

Itr          20

For viscosity:

(RW20.n 1 RW20 DZM.n)      MV

(RW20 DZM.n P4)                  HV

Clamping chuck clamping range:      mm      0,5 -10

Hollow shaft internal diameter:          mm      10,5

Etension arm:

(RW20.n 1 RW20 DZM.n)                  mm      13x160 long

(RW20 DZM.n P4)                              mm      16x160 Iong

Housing:                                              Al diecasting, thermoplastic

                                               RW20.n                       RW20 DZM.n             RW20 DZM.n P4

Dimensions without exten‑

sion arm (WxDxH)     mm     88x188x292                88x210x292                88x210x402

Gewicht mit Ausleger

und Spannfutter:          kg         2,9                               3,1                               4,6