Siemens CA 333 Series Spezifikationen PDF herunterladen (Seite 4)

SD74

1.0 INTRODUCTION

This instruction describes the installation, operation, and maintenance of the Model Series 74 Valve Positioner and

Motion Transmitter. The Model Series 74 is a two-stage, high frequency response valve positioner. The positioner

incorporates dual outputs which makes it ideally suited for double-acting cylinder operators. When one output is

supplying air, the other is exhausting it. This action provides large differential forces to drive the actuator to the

desired position. The Model Series 74 is also used as a single-acting positioner for spring type and cushion-load

actuators. In this case, only one positioner output is used.

The Model 74S can be used as a motion transmitter. It delivers a 3-15 psig output for input motion spans from 1/4"

to 48". For this application, a stabilizing restriction is added to the positioner piping. Normally the Model 74S is

used on small-bore cylinder operators of limited volume (generally 4" I.D. and smaller).

IMPORTANT

Save this Instruction and make it available for installation and maintenance of the

instrument.

1.1 MODEL DESIGNATION

Sample Model Number 74 S G – 1

Basic Model Number

S – with Stabilizing Pilot and Reduced Gain

Blank – Standard Positioner

G – with (3) Gauges

N – without Gauges

With Standard Pilot and Reduced Gain

1.2 SPECIFICATIONS

Input Ranges................................................................3-15, 3-9, 3-27, 0-15 and 0-30 including split ranges within

these basic ranges

Valve Stroke, Rectilinear Range Spring

Minimum..............................................................1/4"

Maximum .............................................................48"

Valve Stroke, Rotary Range Spring ............................90° travel CW or CCW

Supply Pressure

Minimum..............................................................3 psi above full actuator pressure required

Maximum .............................................................150 psig

Ambient Temperature Limits ......................................-40°C to +82°C (-40°F to +180°F)

The Model Series 74 has been designed and manufactured in accordance with Article 3, Paragraph 3 of Pressure

Equipment Directive 97/23/EC.

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Siemens CA 333 Series Spezifikationen Seite 4