NI-205E
INSTRUCTION MANUAL
Rev. 1 12/02
ABSOLUTE PRESSURE SWITCHES
WEATHERPROOF: SERIES APW EXPLOSIONPROOF: SERIES APA
Models APWH, APWL
Models APAH, APAL
B
A
A pressure attachment
B cable entry
Models APW10
B
WEIGHT 5,5 kg
(dimensions in mm)
B
A
A vacuum attachment
B cable entry
Models APA10
B
WEIGHT 6,5 kg
(dimensions in mm)
A
A pressure attachment
B cable entry
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.
SAFETY INSTRUCTIONS FOR USE IN HAZARDOUS ATMOSPHERES.
RECOMMENDATIONS FOR PRESSURE SWITCH SAFE USE.
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.
WEIGHT 8,2 kg
(dimensions in mm)
A vacuum attachment
B cable entry
A
WEIGHT 10 kg
(dimensions in mm)
RELATED DOCUMENT
To authentified document with certificate
N° CESI 03 ATEX 004
INSTRUCTION MANUAL
1. GENERAL NOTES
1.1 FOREWORD
APW and APA series were designed for applications
where absolute-zero rather than atmospheric set point
value is required (see fig.1)
Fig. 1 -
Pressure designation
NI-205E
Rev. 1 12/02
1.5 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° to +70°C).
Therefore, in case it does, suitable measures (protection
against heat radiation, fluid separators, cooling coils,
heated lockers) must be taken. Process fluid or its solid
particles must not however go inside instrument
chambers.
2. OPERATING PRINCIPLE
The process pressure, acting on the diaphragm
sensitive element, that has got absolute vacuum as
reference pressure, 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 differential gap (difference
between the set point value and the reset value) can be
set or adjustable (letter R in the contact codes).
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 APA) – also the
markings prescribed by standard CEI EN 50014. Fig. 2
shows the plate mounted on explosionproof instruments.
Fig. 2 - Explosionproof instruments plate
1.2 RANGE CHOICE
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.
1.3 ALLOWED OVERRANGE
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 overranges can have a destructive effect on
the switch.
1.4 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 a good idea to take measures to lessen
the effects (elastic supports, installation with the peg of
the microswitch positioned at right angles to the
vibration plane, etc.).
1 CE marking and identifi cation 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 t he type certi ficat e and number of
said certificate.
4. SET POINT REGULATION
Each microswitch is independent and can be regulated
by means of a screw (for adjustment) in such a way that
it is released when the pressure reaches (increasing or
decreasing) 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 calibrated 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.
INSTRUCTION MANUAL
The position of the adjustment screws is given in figure
The effect that the direction of rotation of the
Fig. 3 One contact instruments Two contact instruments
Electrical connections and adjustment screws
NI-205E
Rev. 1 12/02
adjustment screws has is described on the adhesive
plate.
Microswitch electrical circuit
State of the contacts at
atmospheric press ure
1 - Microswitch set point cal i brat i on
screws
3 - Terminal block
4 - Electrical connection identification
plate
5. SET POINT CALIBRATION
In order to proceed with the calibration and the
periodical functional verification of the instrument a
suitable calibration circuit (fig. 6) and an adequate
pressure source is required.
5.1 PRELIMINARY OPERATIONS
Weatherproof pressure switches (Series APW) (Fig.
4)
Remove the blocking device fixed to the side of the
instrument case and the adjustment screw access plate.
Remove the cover by rotating it in an anticlockwise
direction.
Fig. 4 -
device
a - Plumbing wire
b - Plumbing
c - Blocking nut
Explosionproof pressure switches (Series APA)
(Fig.5)
CAUTION: do not open the cover of explosionproof
pressure switches (Series APA) when energized, in
explosive atmospheres.
Loosen the locking headless screw situated on the
cover using a 1,5 hexagonal key then unscrew the
cover. Remove the internal blocking device inserted on
the closure plugs and slide out the plugs.
Weatherproof press ure switch blocking and plumbi ng
1 - Microswitch 2 set point cal i brat i on screws
2 - Microswitch 1 set point cal i brat i on screws
3 - Terminal block
4 - Electrical connection identification plat e
d - Blocking bracket
e - Adjustment screw access
plate
Designation of the contac ts:
C - common
NA - Normally open
NC - Normally closed
Fig. 5 - Explosionproof pressure switch blocking devic e
5.2 CALIBRATION CIRCUIT AND OPERATIONS
Prepare the control circuit as indicated in Fig.5.
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.
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 precision required to calibrate the set
point.
INSTRUCTION MANUAL
The pressure switch must be mounted in the normal
installation position, i.e. with the pressure connection
pointing downwards.
Fig. 6 -
PS - Pressure switch
CA - Test pressure gauge for
V1 - Inlet valve
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 of contacts code) before proceeding
with the following operations it is necessary to proceed
with the adjustment of the dead band (see attachment
NI-704).
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
adhesive plate, 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 (fig. 3).
Act on the adjustment screw of the second contact.
Repeat former operations on the first contact, then
operations on the second contact, until the required set
point precision is obtained. This is necessary due to the
reciprocal influence which the microswitches have on
the sensitive element of the instrument.
Check the calibration values (varying the pressure in the
circuit accordingly) and record them on the adhesive
plate using a pen with indelible ink.
5.3 FINAL OPERATIONS
Disconnect the instrument from the calibration circuit.
Weatherproof pressure switches (Series APW)
Take the cover, ensure that the sealing gasket is
correctly fitted into its seat, and insert the cover onto the
case, with the blocking gap positioned in
correspondence to the blocking bracket. Turn the cover
clockwise closing it tightly. Mount the adjustment screw
access plate, then the blocking device as in Fig.4.
Explosionproof pressure switches (Series APA).
Insert the closure plugs of the adjustment screw access
holes, block them using the internal device and if
necessary seal them with plumbing. Screw on the cover
and block it using the headless screw with which it is
equipped (Fig. 5).
Replace the supplied protection caps on the pressure
attachment and cable conduit.
IMPORTANT: the protection caps should only be
definitively removed during the connection steps (see
§6).
Calibration circuit
Absolute
Pressione
pressure
assoluta
absolute pressuures
V2 - Outlet valve
P - Absolute pressure
source
NI-205
Rev. 1 12/02
6. MOUNTING AND CONNECTIONS
6.1 MOUNTING
Surface mount the instrument by means of the holes
provided, or pipe mount using the appropriate bracket
(see Fig. 9). The chosen position must be such that
vibrations, the possibility of shocks or temperature
changes are within tolerable limits. The above also
applies to direct mounting. With gas or vapour process
fluid, the instrument must be positioned higher than the
pipe inlet (see Fig. 8). With a liquid process fluid, the
instrument can be positioned higher or lower,
indifferently (see Fig. 8 and 9). ). In this case, during set
point calibration the negative or positive head must be
taken into account (distance h in fig.8 and 9).
6.2 PRESSURE CONNECTIONS
For a correct installation it is necessary to:
Mount a shut-off valve with drain (root valve) on the
process tube to allow the instrument to be excluded and
the connection tubing to be drained. It is recommended
that said valve has a capstan-blocking device aimed at
preventing it being activated casually and without
authorisation.
Mount a service valve near the instrument to permit
possible functional verification on site. It is
recommended that the service valve is closed with a
plug to prevent the outlet of the process fluid caused by
the incorrect use of said valve.
Mount a three-piece joint onto the threaded attachment
of the instrument to permit the easy mounting or
removal of the instrument itself.
Carry out the connection using a flexible tube in such a
way that variations in the temperature of the tube itself
do not force the instrument attachment.
Ensure that all the pressure connections are airtight. It
is important that there are no leakage in the circuit.
Close the root valve and the relative drain device. Close
the service valve using a safety plug.
6.3 ELECTRICAL CONNECTIONS
It is recommended to carry out the electrical
connections according to the applicable standards. In
case of explosionproof instruments (Series APA) see
also the Standard EN-60079-14. If the electrical
connection is carried out in a protected tube, it shall be
made so that condensate is prevented from entering
instrument enclosure.
The arrangement shown in fig. 8 and 9 is therefore
recommended.
CAUTION: fittings used for the electrical connection of
the pressure switch Series APA (explosionproof) shall
be certified to Standards EN 50014 and 50018, and
shall guarantee instrument degree of protection (IP65).
Check that there is no power in the lines. Remove the
cover and carry out the cabling and connections to the
terminal block (see Fig. 3). Flexible cables with a
maximum section of 1.2 mm
recommended using the pre-insulated fork thimbles. Do
not touch the adjustment screws and do not bend
the elastic microswitch supports in order to prevent the
instrument calibration being altered. Ensure that no
deposits or wire ends remain inside the case.
As soon as connection steps are completed, mount the
cover on and make sure it is tight and blocked. See Fig.
4 and 5.
2
(16AWG) are
INSTRUCTION MANUAL
6.4 SPECIAL NOTE FOR INSTALLATION OF
CATEGORY 1 / 2 G PRESSURE SWITCHES
Explosionproof pressure switches (Series APA) can be
installed on processes requiring apparatus of group II
category 1 in an ambient requiring apparatus of group II
category 2 (see Fig. 7).
Fig. 7 - Installation of Group II Cat. 1 / 2 G i ns truments
7. INSTRUMENT PLUMBING
Weatherproof pressure switches (Series APW)
The plumbing, aimed as a guarantee against possible
tampering of the calibration and electrical connections,
can be carried out using a flexible steel wire (a) inserted
into the holes in the screw (c) and the bracket (d)
provided for this purpose (see Fig. 4).
Explosionproof pressure switches (Series APA)
Plumbing is not necessary as the cover is blocked with a
headless screw, the closure plugs of the adjustment
screw access holes are blocked by means of the
internal blocking device and the instrument does not
have to be opened when installed (see Fig. 5).
8. PUTTING INTO OPERATION
NI-205
Rev. 1 12/02
As the signal transmitted by the instrument is used in a
complex system, it is necessary that the means of
putting it into operation are established by those in
charge of the plant.
The instrument comes into operation as soon as the root
valve is opened. Any possible drainage of the
connection tubing can be carried out by removing the
safety plug and opening the service valve with the
necessary caution.
In case of explosionproof instruments (Series APA),
initial inspections are to be carried out according to
customer procedures and at least in accordance with
Standard EN-60079-17.
9. FUNCTIONAL VERIFICATION
This will be carried out according to the Client’s control
procedures. Series APW instruments can be verified on
the plant if installed as illustrated in Fig. 8 or 9.
The instruments Series APA may be checked on site
only if apparatus suitable for explosive atmospheres are
used and provided that the electric line is not
energized.
If this is not the case it is necessary to stop operation,
dismount by means of the three-piece joints and carry
out the verification in a test room.
CAUTION: do not open the cover of explosionproof
pressure switches (Series APA) when energized, in
explosive atmospheres.
Verification consists in checking the calibration value
and possibly regulating the adjustment screw (see
para.5).
In case of explosionproof instruments (Series APA),
inspections of the electrical installation are to be carried
out also according to customer procedures and at least
in accordance with Standard EN-60079-17.
10. TROUBLESHOOTING
IMPORTANT NOTE: operations involving replacement of essential components must be carried out at our
workshop, especially for instruments with explosionproof certificate; this is to guarantee the user the total and
correct restoration of the product original characteristics.
MALFUNCTION PROBABLE CAUSE REMEDY
Recalibrate or replace instrument with another
suitable for application.
Recalibrate or replace the instrument with
another having sensitive element made of a
suitable material.
Check and clean line.
Open valves.
Open the valves.
Close the valve.
Replace the Microswitch.
Check all electrical joints.
Check the conditions of the electrical line.
Modify the mounting.
Set point shift
Slow response
No actuation or
undue actuation
Undue actuation
Permanent deformation of the sensitive
element due to fatigue or non-tolerated
overranges.
Variation of the elastic features of the
sensitive element due to its chemical
corrosion.
Clogged or obstructed connection line.
Root or service valves partially closed.
Root or service valves closed.
By-pass valve opened.
Microswitch contacts damaged.
Loosened electrical joints.
Interrupted or short-circuited electrical line.
Accidental shocks or excessive mechanical
vibrations.
NI-205
p
INSTRUCTION MANUAL
11. STOPPING AND DISMOUNTING
Before proceeding with these operations ensure that
the plant or machines have been put into the
conditions foreseen to allow these operations.
With reference to figures 8 and 9
Remove the power supply (signal) from the electrical
line. Close the root valve (6) and open the drain.
Remove the plug (2), open the valve (3) and wait until
the process fluid has drained from the tubing through
the drain.
Do not dispose of the process fluid into the environment,
if this can cause pollution or damage to people.
Unscrew the three-piece joint (8).
CAUTION: do not open the cover of explosionproof
pressure switches (Series APA) when energized, in
explosive atmospheres.
Unscrew the three-piece joint (10) (electrical cable
tubing).
Remove the instrument cover and disconnect the
electrical cables from the terminal block and earth
WEATHERPROOF EXPLOSIONPROOF
Fig. 8 - Example of connections - Fig. 9 - Example of connections -
screws. Remove the screws fixing the case to the panel
(or pipe) and remove the instrument, taking care to slide
the electrical conductors out from the case.
Replace the instrument cover. Insulate and protect the
conductors remaining on the plant. Temporarily plug the
tubing (4).
In case of explosionproof instruments (Series APA) it is
recommended to follow - at least – the standard EN60079-17 for the withdrawal from service of electrical
apparatus.
12. DEMOLITION
The instruments are mainly made of stainless steel and
aluminium and therefore, once the electrical parts have
been dismounted and the parts coming into contact with
fluids which could be harmful to people or the
environment have been properly dealt with, they can be
scrapped.
Rev. 1 12/02
1 – Fitting
2 - Drain plug
3 - Service valve
4 - Piping
Fig. 10 - Exam
le of mounting
5 - Three piece fitting
6 - Root valve with drain
7 - Process piping
8 - Three piece fitting
9 - “T” fitting
10 - Three piece fitting
11 - Curve
12 - Blocking joint
13 - M6 screws (No. 4)
14 - Bracket for 2” pipe
15 - Vertical pipe
16 - Horizontal pipe
Surface mounting
Montaggio a parete
ETTORE CELLA SPA Viale de Gasperi, 48 - Casella Postale (P.O. Box) 96 - I 20010 Bareggio (MILANO) ITALY
Telefoni +39 029036.1146/7 - 029036.1237/41 - FAX +39 029036.1331 Email: CELLA@ECELLASPA.COM
2” pipe mounting
Montaggio su staffa per tubo da 2”
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