WIKA PCA-HP User Manual

NI-281E

INSTRUCTION MANUAL

Rev. 5 11/02

COMPACT PRESS. SWITCHES SERIES PCS & PCA

WEATHERPROOF EXPLOSIONPROOF

SERIES PCS SERIES PCA

B = Cable entry A = Pressure connection WEIGHT 1kg dimensions in mm

NOTE: dimensions and weights are not binding unless released on certified drawings.

CAUTION

• Before installing, using or carrying out maintenance on the instrument it is necessary to read and understand the indications given in the attached Instruction Manual.

• The instrument must only be installed and maintained by qualified personnel.

• INSTALLATION IS TO BE CARRIED OUT ONLY AFTER CHECKING THAT INSTRUMENT CHARACTERISTICS ARE

CONSISTENT WITH PROCESS AND PLANT REQUIREMENTS

• The functional features of the instrument and its degree of protection are shown on the identification plate fixed to the case.

CONTENTS:

GENERAL NOTES

1 -

2 - OPERATING PRINCIPLE

3 - IDENTIFICATION PLATE AND MARKINGS

4 - SET POINT REGULATION 5 - SET POINT CALIBRATION 6 - MOUNTING AND CONNECTIONS 7 - INSTRUMENT PLUMBING 8 - PUTTING INTO OPERATION 9 - FUNCTIONAL VERIFICATION 10 - FUNCTIONAL VERIFICATION 11 - STOPPING AND DISMOUNTING 12 - DEMOLITION

SAFETY INSTRUCTIONS FOR USE IN HAZARDOUS ATMOSPHERES. RECOMMENDATIONS FOR PRESSURE SWITCH SAFE USE.

B = Cable entry A = Pressure connection WEIGHT 1kg dimensions in mm

RELATED DOCUMENT

To authentified document with certificate

N° CESI 02 ATEX 118

ll data, statements and recommendations supplied with this manual are based on information believed by us to be reliable. As the onditions of effective use are beyond our control, our products are sold under the condition that the user himself evaluates such onditions before following our recommendations for the purpose or use foreseen by him.

The present document is the property of ETTORE CELLA SPA and may not be reproduced in any form, nor used for any purpose other than for which it is supplied.

INSTRUCTION MANUAL

1 - GENERAL NOTES

1.1 FOREWORD

The wrong choice of a series or a model, as well as the incorrect installation, lead to malfunction and reduce instrument life. Failure to abide by the indications given in this manual can cause damage to the instrument, the environment and persons.

1.2 ALLOWED OVERRANGE

Pressures exceeding the working range can be occasionally tolerated provided they remain within the limits stated in the instrument features (proof pressure). Continuous pressures exceeding the working range can be applied to the instrument, provided they are clearly stated in the instrument features. The current and voltage values stated in the technical specifications and ratings must not be exceeded. Transitory over-ranges can have a destructive effect on the switch.

1.3 TEMPERATURE

Due to the temperature of both the environment and the process fluid, the temperature of the instrument could exceed the allowed limits (normally from -20°C to +70°C). Therefore, in case it does, suitable measures (protection against heat radiation, fluid separators, cooling coils, heated lockers), aimed at limiting the value, must be taken.

2 - OPERATING PRINCIPLE

A pressure-tight diaphragm (or an O-ring sealed piston) applies a force to a stiff disc. This force is directly proportional to the pressure value and is contrasted by an helicoidal spring charged by a suitable bush. When the force balance point is exceeded, the stiff disc shifts and, by means of a rigid rod, actuates one or two simultaneous release electric microswitches. The microswitches are of the snap acting type with automatic reset. When the pressure moves away from the set values, returning towards the normal values, the switch is reset.

3 - IDENTIFICATION PLATE AND MARKINGS

The instrument is fitted with a metal plate bearing all its functional characteristics and – in case of explosionproof execution (Series PCA) – also the markings prescribed by standard CEI EN 50014. Fig. 1 shows the plate mounted on explosionproof instruments.

Fig. 1 - Explosionproof instruments plate

NI-281E

Rev. 5 11/02

Prior to installation the instrument must be calibrated and the definitive calibration values written on the label using a suitable indelible ink pen.

If the instrument has been ordered with a specific calibration, it is a good rule to check the calibration values marked on the relevant adhesive label, prior to installation.

The position of the adjustment bush given in Fig. 2.

Fig. 2 - Electrical connections and adjustment screws

(one contact/two contact instruments)

1 - External earth screw 2 - Hole for test plug 3 - Adjustment rod for set point calibration 4 - Adjustment bush access plate 5 - Adjustment bush 6 - Screw for fixing the adjustment bush access plate 7 - Internal earth screw 8 - Terminal block for the second microswitch

9 - Terminal block for the first microswitch 10 - Pre-insulated thimbles ⊗ - Ventilation path Microswitch electrical circuit. State of the contacts at atmospheric pressure

1 CE marking and identification number of the notified body

responsible for production surveillance.

2 Apparatus classification according to ATEX 94/9 CE

directive..

3 Type of protection and ambient temperature limits of

operation.

4 Notified body that issued the type certificate and number of

said certificate.

4 - SET POINT REGULATION

The charge of the helicoidal spring can be regulated by means of the bush (for adjustment) in such a way that the switch is released when the pressure reaches (increasing or decreasing) the desired values (set point). The instrument is usually supplied with the switches set at the setting range value nearest to zero (factory calibration). The instrument is supplied with an adhesive label showing the set point calibration value. With factory calibration the values are not indicated on the label as these are temporary and will be modified with the definitive values.

Designation of the contacts:

C - Common NA - Normally open NC - Normally closed

The effect of the direction of rotation of the adjustment bush has is described on the adhesive plate. The bush must be turned by means of the special adjustment rod which comes with the instrument (Fig.2).

5 - SET POINT CALIBRATION

In order to proceed with the calibration and the periodical functional verification of the instrument a suitable calibration circuit (Fig. 4) and an adequate pressure source is required..

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