WIKA DE User Manual
NI-223E
INSTRUCTION MANUAL
COMPACT DIFF. PRESSURE SWITCHES SERIES DC & DE
WEATHERPROOF EXPLOSIONPROOF
SERIES DC SERIES DE
Rev. 2 11/02
Sfiati
vents
A High pressure connection
B Low pressure connection
WEIGHT 5,4 kg dimensions in mm WEIGHT 5,4 kg 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.
CONTENUTO
1 - GENERAL NOTES
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 - TROUBLESHOOTING
11 - STOPPING AND DISMOUNTING
12 - DEMOLITION
SAFETY INSTRUCTIONS FOR USE IN HAZARDOUS ATMOSPHERES.
RECOMMENDATIONS FOR PRESSURE SWITCH SAFE USE.
C Cable entry A High pressure connection
B Low pressure connection
RELATED DOCUMENT
To authentified document with certificate
N° CESI 02 ATEX 119
Sfiati
vents
C Cable entry
All data, statements and recommendations supplied with this manual are based on information believed by us to be reliable. As the
conditions of effective use are beyond our control, our products are sold under the condition that the user himself evaluates such
conditions 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 that 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 follow the indications given in this manual can cause damage to the instrument, the environment and persons.
1.2 ALLOWED OVERRANGE
Differential pressure exceeding the working range can be occasionally tolerated provided they remain within the limits stated in
the instrument features (vacuum or proof pressure). Continuous
differential pressure 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 MECHANICAL VIBRATIONS
Can generally lead to the wearing of some parts of the instrument
or cause false actuation. It is therefore recommended that the instrument be installed in a place where there are no vibrations. In
cases where this is impossible it is advisable to take measures to
lessen the effects (elastic supports, installation with the pin of the
microswitch positioned at right angles to the vibration plane, etc.).
1.4 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 -40° to +60°C). Therefore, in case it does,
suitable measures (protection against heat radiation, fluid separators, cooling coils, heated lockers) must be taken. The process
fluid or its impurities must not in any case solidify inside the instrument chambers.
2 - OPERATING PRINCIPLE
The differential pressure, acting on the sensitive diaphragm element, determines its elastic deformation which is used to actuate
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
DE) – also the markings prescribed by standard CEI EN 50014.
Fig. 1 shows the plate mounted on explosionproof instruments.
NI-223E
Rev. 2 11/02
Fig. 1 - Explosionproof instruments plate
1 CE marking and identification number of the notified body
responsible for production surveillance.
2 Apparatus classification according to ATEX 94/9 CE direc-
tive.
3 Type of protection and ambient temperature limits of opera-
tion.
4 Notified body that issued the type certificate and number of
said certificate.
4 - SET POINT REGULATION
Adjustment is made by turning a screw that makes the
switch/switches activate when the pressure (increasing or decreasing) reaches the desired value (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 rating plate showing the set point calibration
value. With factory calibration the values are not indicated on
the ratings as these are temporary and will be modified with the
definitive values. Prior to installation the instrument must be cali-
brated and the definitive calibration values written on the adhesive rating plate 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 adjustment screw (fig.2) , which acts on the switch, is part of
the transmission system for shifting the sensor element. The adjustment must therefore be made very carefully. To facilitate the
calibration operation (§ 5.2) , its seat is provided with a graduated
scale; each increment of this scale equals approximately 5% of
the full range of the differential pressure switch. Therefore, using
the slot on the top of the adjustment screw as a reference, the
screw can be turned to obtain a certain value.
The effect that the direction of rotation of the adjustment screws
has is described on the adhesive plate.
Fig. 2 - Electrical connections and adjustament screws with one or two contacts instruments
INSTRUCTION MANUAL
1 - Adjustment screw
2 - Screw for fixing the adjustement
3 - Terminal block for the first microswitch
4 - Hole for test plug
5 - Terminal block for the first microswitch
6 - Internal earth screw
7 - Pre-insulated thimbles
8 - External earth screw
9 - Adjustment bush access plate
10 - Graduated dial
Microswitch electrical circuit.
State of the contacts at atmospheric pressure
NI-223E
Rev. 2 11/02
≅ 5% span
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.
5.1 PRELIMINARY OPERATIONS
CAUTION: do not open the cover of explosionproof pressure
switches (Series DE) when energized, in explosive atmospheres.
With reference to fig.3 unscrew the screw (b) until the blocking
device (a) can be turned 180°; then unscrew the cover.
Fig. 3 - Cover blocking device and plumbing
Designation of the contacts:
C – Common
NA – Normaly open
NC – Normaly closed
plug with a diameter of 2 mm to be inserted in the appropriate
holes situated frontally beside the terminal screw (see fig.2).
Connection of C and NO terminals
• If the circuit is open at the working pressure, the switch closes
the circuit as the pressure increases when the desired values is
reached (MAKE on Raise).
• If the circuit is closed at the working pressure, the switch opens
the circuit as the pressure decreases when the desired value is
reached (BREAK on Fall).
Connection of C and NC terminals
• If the circuit is closed at the working pressure, the switch opens
the circuit as the pressure increases when the desired value is
reached (BREAK on Raise).
• If the circuit is open at the working pressure, the switch closes
the circuit as the pressure decreases when the desired value is
reached (MAKE on Fall).
The test instrument should have a measurement range approximately equal to or slightly wider than the differential pressure
switch range and should have an accuracy consistent with the
precision required to calibrate the set point.
The differential pressure switch must be mounted in the normal
installation position, i.e. with the pressure connections downwards.
Fig. 4 - Calibration circuit
a - Cover blocking device
b - Blocking screw
c - Screw blocking the adjustment bush access plate
d - Flexible steel wire
e - Plumbing
f - Adjustment bush access plate
5.2 CALIBRATION CIRCUIT AND OPERATIONS
Prepare the control circuit as indicated in Fig. 3 by connecting the
+ (or H) port to the pressure source and leaving the - (or L) port
open to the atmosphere.
The warning lamps should be connected to the contacts in the
NA or NC (NA = Normally Open NC = Normally Closed) position
according to the required contact action.
If the instrument is equipped with two microswitches, take into
account that they actuate simultaneously within rated tolerances.
The warning lamps can either be connected by means of a thimble with a maximum diameter of 2.5 mm or by means of a test
DPS Differential pressure switches Test fluid:
CA Test gauge air for P ≤ 10 bar
V1 Inlet valve water for P > 10 bar
V2 Discharge valve
P Pressure source
Avoid forcing the microswitch by hand or with tools. This could affect the instrument functioning.
With reference to fig.3, clear the access to the adjustment bush
by loosening the screw (c) which holds the access plate (f).
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