Instruction Manual

GENERAL
The unit is manufactured, checked and supplied in
accordance with our published specification, and when
installed and used in normal or prescribed
applications, with the lid in place and within the
parameters set for mechanical and electrical
performance, will not cause danger or hazard to life or
limb.
HEALTH AND SAFETY AT WORK ACT 1974
WARNINGS
1. THE USERS ATTENTION IS DRAWN TO
THE FACT THAT, WHEN THE UNIT IS ‘LIVE’
WITH RESPECT TO ELECTRICAL OR
PRESSURE SUPPLIES, A HAZARD MAY
EXIST IF THE UNIT IS OPENED OR
DISMANTLED.
2. UNITS MUST BE SELECTED AND
INSTALLED BY SUITABLY TRAINED AND
QUALIFIED PERSONNEL IN ACCORDANCE
WITH APPROPRIATE CODES OF PRACTICE
SO THAT THE POSSIBILITY OF FAILURE
RESULTING IN INJURY OR DAMAGE
CAUSED BY MISUSE OR MISAPPLICATION
IS AVOIDED.
OPERATING PRINCIPLES
A diaphragm is used to sense the difference between
two pressures applied to either side of the diaphragm.
The diaphragm transmits a force proportional to the
applied pressure difference to a push rod. The rod is
restrained by an adjustable spring. When the force on
the rod overcomes the spring tension the rod moves
and operates a switch or switches. On reduction of
the applied pressure difference the force applied to the
rod also falls, the rod is restored to its original position
by the spring, and the switch or switches reset.
TERMINAL ENCLOSURE CODE K (Fig 4 & 9)
– INSTALLATION
Terminal enclosure is rated IP65 for outdoor use.
This is a certified enclosure Zone 1 (Div 1) IEC 79-1
BS 5501: Parts 1 and 5: EN 50 014 and EN 50 018
EExd IIC T6.
Instrument enclosure is certified to Zone 1 (Div 1) IEC
79-1 BS 5501: Parts 1 and 5: EN 50 014 and EN 50
018 Cenelec.
WARNING: Lid and adaptors. It is a safety
requirement that at least 5 full threads are engaged
when the unit is in operation. Never operate the unit
unless this condition is met. Do not use greases or
lubricants not compatible with the environment,
process or aluminium.
REPLACEMENT PARTS
Use only factory authorised parts and procedures.
The only parts normally recommended for site
replacement are the microswitches. However, in some
circumstances other spares kits are available. Apply
for details quoting the serial number and full product
code.
WARRANTIES – SEE CONDITIONS OF SALE
PRODUCT CODE
ENCLOSURE
MODEL
ELECTRICAL ENTRY
MATERIAL OF WETTED PARTS
RANGE
SWITCHING OPTIONS
PROCESS CONNECTION
OPTIONS AND TREATMENTS
SPECIAL ENGINEERING
ESGAAN DOWNWARD FACING CONNECTIONS
INSTALLATION
The instruments are designed to be mounted vertically.
They can be mounted either direct to process or to a wall
or panel using the backplate provided. Select the
mounting point so as to avoid excessive shock, vibration or
temperature fluctuation. Instruments should be mounted
to avoid excessive heat transfer from the process lines or
adjacent plant.
If sudden changes of pressure (pulsations) are likely then
we recommend that snubbers are fitted between the
process line and switch.
Use a spanner to support the process connection when
fitting the instrument. DO NOT OVERTIGHTEN.
WARNING: CHECK THE CONNECTION THREAD SIZE
AND SPECIFICATION ON THE UNIT TO AVOID
MISMATCHING WITH THE PROCESS CONNECTION
ADAPTOR. SEE DIGIT 11 OF PRODUCT CODE.
WIRING (Fig 1)
Terminal Enclosure Version (Fig 4)
Wire in accordance with local and national codes. Use
cables no larger than 2.5 mm2 (14 AWG). Deliver
electrical connection through a suitable cable gland, which
will maintain the IP rating of the instrument. Insert bare
wires fully into the terminal block and tighten securely.
Keep wiring tails to a minimum.
Flying Lead Version
The leads are factory sealed so it is unnecessary to seal
the conduit to the conduit nipple. However, flying leads
must be terminated in accordance with local and national
codes. Each conductor is provided with an identity tag. If
these become detached refer to the colour code in the
wiring diagram.
CERTIFIED ENCLOSURES
All Series GR Pressure Difference Switches can be
supplied with BASEEFA certified enclosures to the
following standards:
Zone 1 (Div 1) IEC 79-1
BS 5501: Parts 1 and 5: EN 50 014 and EN 50 018
CENELEC. Codes ‘H’ for aluminium and ‘R’ for stainless
steel EExd IIC T6.
All enclosures are suitable for outdoor use and the majority
of products are rated IP66. Refer to the product label
and/or leaflet. Only operation, maintenance or repair
procedures either contained herein or approved by Delta
Controls may be used, to avoid rendering the equipment
unsafe in operation and / or nullifying the Certification. NO
MODIFICATIONS ARE PERMITTED.
Special Conditions for Safe Use
The integral wires shall be suitably protected against
mechanical damage and be terminated within a terminal or
junction facility suitable for the conditions of use.
Electrical Adaptors
Zone 1. Use only certified adaptors for Zone 1.
EExe for increased safety installations and EExd for
Flameproof installations.
References for Selection and Installation
BSEN60079-14 Part4 for all Enclosure Codes (Intrinsic
Safety)
BSEN 50014 Part 1 for Enclosure Codes H, R
BSEN60529 IP RATING (Ingress Protection)
MAINTENANCE
Inspections should be carried out at quarterly to yearly
intervals depending upon operating conditions.
Where a terminal enclosure is fitted, isolate the unit from
process and power and remove the lid. Check all
terminals for tightness. Check that cable tails are not
fouled or chafed. Check for internal condensation. Rectify
as necessary.
It is recommended that instruments used to provide an
alarm are operated periodically to ensure they are
functioning correctly.
If further maintenance is required, seek advice from
DELTA CONTROLS before attempting repair or
replacement of parts.
Note: Should the diaphragm fail the process will vent to
atmosphere via a control orifice without pressurising the
switch enclosure. Periodically ensure the vent area does
not become blocked and the vent plug has not degraded.
Ensure that the vent area is not obstructed.
CAUTION
Moving parts have been treated with a water repelling
lubricant before leaving the factory. Occasional inspection
and the application of a water repelling lubricant is
recommended to ensure moving parts remain free under
all conditions.
WARNING: DOES NOT APPLY TO OXYGEN SERVICE.
OPERATION
Pressure difference switches are supplied calibrated
against falling pressure difference unless otherwise
specified. Set Point Adjustment refers to falling pressure
difference. Switching Differential is the difference between
the set point and the operating value on rising pressure
difference.
Set Point Adjustment: Models GR3/6 (fig 3)
1 Isolate the instrument from the process.
2 Adjustment may be carried out with the unit live.
3 Loosen both cover screws.
4 Rotate cover anti-clockwise to allow access.
5 Using a screwdriver rotate the adjuster to obtain the
desired setting. Turn right to left to increase the setting.
An appropriate setting is shown by pointer against
reference scale.
6 Rotate cover clockwise to close and tighten screws.
NOTE: For accurate setting, a suitable gauge must be
used in conjunction with the above procedure. Do not
attempt to set the switch outside the scale limits. Though
the unit may be set anywhere within its operation range,
for optimum performance, it is good practice to have a set
point value between 25% and 75% of span.
PROCESS CONFIGURATIONS (RANGE BC)
For normal pressure difference operation, the connections
are made to the High Pressure (HP) and Low Pressure
(LP) ports as appropriate. For single-ended positive
pressure operation, the HP only is used and the LP is left
open to atmosphere. The single-ended negative pressure
operation, the LP only is used and the HP is left open to
atmosphere.
Use a breather / filter in the vacant port of single-ended
operation.
COMPOUND RANGE eg –12.5 to +12.5 mbar (RANGE BC)
For normal operation, negative pressure may be applied to
the LP port, whereby the HP port is left open to
atmosphere and the set point is between 0 and +12.5
mbar.
For reverse operation, negative pressure may be applied
to the HP port, whereby the LP port is left open to
atmosphere and the set point is between 0 and –12.5
mbar.
For positive pressures the opposite applies.
It is recommended that the minimum setting is to be not
less than 5% of FS either side approaching zero (see fig
2).
ISSUE E 02/10
INSTALLATION, OPERATING AND
MAINTENANCE INSTRUCTIONS FOR
DIAPHRAGM ACTUATED SERIES GR
PRESSURE DIFFERENCE SWITCHES
(MODELS GR3 & GR6)
SWITCH
0
NORMAL
REVERSE
PRESSURE
5 % FS
Fig 2
Fig 3
SCREW
DRIVER
LOCATION
SLOTS
LOWEST SET
POINT
HIGHEST
SET POINT
ADJUST
RIGHT TO
LEFT TO
INCREASE
SET POINT