WIKA MWB, MW, MWH, MAB, MAH Instruction Manual
...
INSTRUCTION MANUAL
NI-221WE
REV. 5 12/16
WEATHERPROOF AND INTRINSICALLY SAFE: MODEL MW FLAMEPROOF: MODEL MA
Versions: MWB-MW-MWH-MWG Versions: MAB-MA-MAH-MAG
A
= pressure attachment
B
= cable entry
For surface mounting use two screws M6
WEIGHT 1,8 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.
CONTENTS:
GENERAL NOTES
1
2OPERATING PRINCIPLE
3MODEL CODE
4IDENTIFICATION PLATE AND MARKINGS
5SET POINT REGULATION
6SET POIT CALIBRATION
7MOUNTING AND CONNECTIONS
8INSTRUMENT PLUMBING
9SAFETY INTEGRITY LEVEL (SIL) INSTALLATION REQUIREMENTS
10PUTTING INTO OPERATION
11VISUAL INSPECTION
12FUNCTIONAL VERIFICATION
13STOPPING AND DISMOUNTING
14DISPOSAL
15TROUBLESHOOTING
SAFETY INSTRUCTIONS FOR USE IN HAZARDOUS ATMOSPHERES.
RECOMMENDATIONS FOR PRESSURE SWITCH SAFE USE.
DIAPHRAGM PRESSURE SWITCHES
A
= pressure attachment
B
= cable entry
For surface mounting use four screws M6
WEIGHT 3,2 kg Dimensions in mm
RELATED DOCUMENT
To authentified document with certificate
N° IECEx PRE 16.0067X
N° IECEx PRE 16.0074X
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 ALEXANDER WIEGAND SE &Co and may not be reproduced in any form, nor used for any
purpose other than that for which it is supplied.
1
GENERAL NOTES
1.1
FOREWORD
The wrong choice of a model/ version, 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 OVERR ANGE
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 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 overages can have a destructive effect on the switch.
1.3
MECHANICAL VIBRATION
Can generally lead to the wearing of some parts of the instrument
or cause spurious action. 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 a good idea to take measures
to lessen the effects (elastic supports, installation with the switch
plunger of the microswitch positioned at right angles to the vibration plane).
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 however solidify in the instrument.
2
OPERATING PRINCIPLE
The pressure, acting on the sensitive element (diaphragm), determines its elastic deformation which is used to activate one or two
electric microswitches regulated at set point values. The microswitches are of the rapid release type with automatic rearm. When
the pressure moves away from the set values, returning towards
the normal values, the switch is rearmed. The dead band (gap between the set point value and the reset value) can be fixed or adjustable (letter R in the contact codes).
The versions with sensing element H or G are piston activated diaphragm instruments. The pressure, acting on a piston element,
generates a force which, applied to the diaphragm, causes an elastic deformation.
3
MODEL CODE
See Annex 1
4
IDENTIFICATION PLATE AND MARKINGS
The instrument is fitted with a metal plate bearing all its functional
characteristics and in case of flameproof or intrinsic safety execution also the markings prescribed by standard IEC/EN 60079-0.
Fig.1 shows the plate mounted on flameproof instruments.
Fig. 1 - Flameproof instruments plate
1 Notified body that issued the type certificate and number of said
certificate.
2 CE marking and identification number of the notified body re-
sponsible for production surveillance.
3 Apparatus classification according to ATEX 2014/34/EU di-
rective.
4 Type of protection and ambient temperature limits of operation.
INSTRUCTION MANUAL
NI-221WE
Rev. 5 12/16
The following table gives the relationship between hazardous areas, Atex Categories and Equipment Protection Level (EPL) listed
on the flameproof instrument nameplate
Hazardous area
Gas, vapours, fog Zone 0 1G Ga
Gas, vapours, fog Zone 1 2G or 1G Gb or Ga
Gas, vapours, fog Zone 2 3G, 2G or 1G Gc, Gb or Ga
Dust Zone 20 1D Da
Dust Zone 21 2D or 1D Db or Da
Dust Zone 22 3D, 2D or 1D Dc, Db or Da
5
SET POINT REGULATION
Each microswitch is independent and can be adjusted by means
of a screw (for adjustment) to snap when the pressure reaches
(increasing or decreasing) the desired value (set point). The instrument is usually supplied with the switches adjusted at the setting
range value nearest to zero (factory calibration). The instrument
is supplied with a label showing the set point calibration value. With
factory calibration the values are not indicated, as these are temporary and will be modified with the definitive values. Prior to installation the instrument must be calibrated and the definitive calibration values written on the label.
If the instrument has been ordered with a specific calibration,
check the calibration values marked on the relevant label, prior to
installation.
The position of the adjustment screw is given in figure 2.
Fig. 2 - Electrical connections and adjustment screws
1- Microswitch 1 set point calibration screw
2- Microswitch 2 set point calibration screw
3- Electrical connection identification plate
4- Terminal block
Condition of the contacts at atmosphere pressure
Designation of the contacts:
C - Common
NA - Normally open
NC - Normally closed
The effect that the direction of rotation of the adjustment screw has
is described on the label.
6
SET POIT CALIBRATION
In order to proceed with the calibration and the periodical functional
verification of the instrument a suitable calibration circuit (Fig. 3)
and an adequate pressure source is required. The test instrument
should have a measurement range approximately equal to or
slightly wider than the pressure switch range and should have an
accuracy consistent with the accuracy required to calibrate the set
point.
Categories ac-
cording to
2014/34/EU Directive (ATEX)
EPL
2 of 9
Fig. 3 - Calibration circuit
PS - Pressure switch
CA - Test gauge
V1 - Inlet valve
V2 - Discharge valve
P - Pressure source
6.1
PRELIMINARY OPERATIONS
6.1.1
Weatherproof pressure switches (Model MW)
Remove the blocking device fixed to the side of the instrument
case (Fig. 4).Remove the cover by rotating it in an anticlockwise
direction.
Fig. 4 - Weatherproof pressure switch blocking device
a - Plumbing wire
b - Plumbing
6.1.2
Flameproof pressure switches (Model MA)
CAUTION: do not open the cover of pressure switches when en-
ergized, in explosive atmospheres.
Loosen the locking headless screw situated on the cover using a
1,5 hexagonal key then unscrew the cover (fig.5).
Fig. 5 - Flameproof pressure switch blocking device
Test fluid:
air for P < 10 bar
water for P > 10 bar
c - Nut
d - Blocking bracket
INSTRUCTION MANUAL
NI-221WE
Rev. 5 12/16
The pressure switch must be mounted in the normal installation
position, i.e. with the pressure connection pointing downwards.
Avoid forcing the elastic support of the microswitch by hand or with
tools. This could affect the instrument functioning.
CAUTION: if the switch is of the kind with adjustable dead band
(letter R in the contact codes) before proceeding with the following
operations it is necessary to proceed with the adjustment of the
dead band.
Increase the pressure in the circuit up to the desired set point value
for the first microswitch. Use a wide bladed screwdriver, as indicated on the label, turn the screw until the relative lamp turns on
(or turns off).
- If the instrument is equipped with only one contact the calibration
is complete.
- If it is equipped with two contacts continue in the following manner. Vary the pressure until the desired set point value for the second microswitch is reached. Act on the adjustment screw of the
second contact.
Repeat calibrating operations on the first contact, then on the second contact, until the required set point accuracy is obtained. This
is necessary due to the reciprocal influence which the microswitches have on the sensitive element of the instrument.
CAUTION: if the two set point are different they must be different
for much of 5% of the adjustable span.
6.3
CALIBRATION OF INSTRUMENT WITH SENSING
ELEMENT H AND G
The pressure switches equipped with sensor H and G, are
instruments with a piston sensing element. To perform an high
accuracy calibration, due to the sensing element, it is necessary to
adjust the set point by varying the pressure from the normal
working pressure of operation to the set point.
6.4
CHECK OF SET POINT
Generate the normal working pressure and wait the pressure stabilisation. Vary the pressure into the circuit and record the set point
value. Write the set point values on the adhesive label.
Note: the repeatability should be checked verifying for three times
the set point (Pi) starting always from the same pressure value
(Pw). The pressure cycle should be slowly to give the possibility to
record the set point with accuracy.
6.5
ADJUSTMENT OF DEAD BAND (LETTER R ON THE
MODEL CODE)
The dead band can be adjusted only on the instrument is equipped
with a microswitch, which allows adjusting (Letter R on the model
code). Adjustment may be obtained by rotating the wheel placed
on the microswitch (Fig. 6).
In order to carry out this operation it is advisable to insert thumb
and forefinger of the left hand in the instrument. The instrument is
normally delivered adjusted on the minimum value of its range
(factory calibration).
Fig. 6 – Adjustment of dead band
6.2
CALIBRATION CIRCUIT AND OPERATIONS
Prepare the calibration circuit as indicated in Fig.3.
The warning lamps should be connected to contact 1 or 2 in the
NO or NC position according to the required contact action.
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 value is
reached.
• If the circuit is closed at the working pressure, the switch opens
the circuit as the pressure decreases when the desired value is
reached.
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.
• If the circuit is open at the working pressure, the switch closes
the circuit as the pressure decreases when the desired value is
reached.
Mark
Dead band adjustment wheel
Set point adjustment screw
3 of 9
Loading...