Kobold SCH User manual


Operating Instructions
for
Pressure Switch
Model: SCH

SCH
page 2 SCH K03/0320
1. Contents
1.Contents ........................................................................................................ 2
2.Note .............................................................................................................. 3
3.Instrument Inspection .................................................................................... 3
4.Regulation Use ............................................................................................. 3
4.1Installation and Commissioning ........................................................... 4
4.2Safety Instructions ............................................................................... 4
5.Mechanical Connection ................................................................................. 5
6.Electrical Connection .................................................................................... 6
7.Setting the Switching Pressure ..................................................................... 7
7.1Setting the Switching Pressure with Plug Connection ......................... 7
7.2Setting the Switching Point .................................................................. 7
7.3Setting Switching Difference (only model V) ........................................ 8
8.Special Functions .......................................................................................... 9
8.1Maximum- and Minimum Pressure Limiter (-205 and -206) ................. 9
8.2Two Stage Pressure Switches (- 307 and - 217) ................................. 9
8.3Switching Interval and Schematic Wiring Diagrams ........................... 11
8.4Gold Plated Contacts (-213) .............................................................. 13
8.5SCH-EX- (EEx-d-Version) .................................................................. 13
9.Technical Information .................................................................................. 14
9.1Technical Information SCH-Ex units .................................................. 14
10.Order Codes ............................................................................................... 14
11.EU Declaration of Conformance ................................................................. 15
12.Examination Certificate ............................................................................... 16
Manufactured and sold by:
Kobold Messring GmbH
Nordring 22-24
D-65719 Hofheim
Tel.: [phone]
Fax: [phone]
E-Mail: [email protected]
Internet: www.kobold.com

SCH
SCH K03/0320 page 3
2. Note
Please read these operating instructions before unpacking and putting the unit
into operation. Follow the instructions precisely as described herein.
The devices are only to be used, maintained and serviced by persons familiar
with these operating instructions and in accordance with local regulations apply-
ing to Health & Safety and prevention of accidents.
When used in machines, the measuring unit should be used only when the
machines fulfil the EC-machine guidelines.
as per PED 2014/68/EU
In acc. with Article 4 Paragraph (3), "Sound Engineering Practice", of the PED
2014/68/EU no CE mark.
3. Instrument Inspection
Instruments are inspected before shipping and sent out in perfect condition.
Should damage to a device be visible, we recommend a thorough inspection of
the delivery packaging. In case of damage, please inform your parcel service /
forwarding agent immediately, since they are responsible for damages during
transit.
Scope of delivery:
The standard delivery includes:
 Pressure Switch model: SCH
 Operating Instructions
4. Regulation Use
Any use of the “SCH”, which exceeds the manufacturers specification may invali-
date its warranty. Therefore, any resulting damage is not the responsibility of the
manufacturer. The user assumes all risk for such usage.
Pressure Switches are used for controlling and monitoring pressure in vessels of
all kinds, e.g. for boilers, compressed air reservoirs, hydraulic and pneumatic
plant, refrigeration engineering, water supply systems etc. Suitable types are
available for overpressure, differential pressure and vacuum.

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page 4 SCH K03/0320
4.1 Installation and Commissioning
 Pressure switches must be installed only by personnel trained in this
application area (electric/hydraulic/mechanical) in accordance with the
installation instructions and local legal requirements.
 The devices must be installed (mechanical, pressure-side connection) only
on electro-chemically matched materials, otherwise there is risk of damage
to base metals through contact corrosion which can result in loss of
stability and leakage.
 Caution when touching device – risk of burns. Device can reach a medium
temperature of up to 70 °C. Risk of freezing when working with media up
to -20 °C.
 Do not open wiring-box or plug and do not remove terminal screws before
the device is de-energized.
 Ex versions are limited to an operating range of -20 … +60 °C.
4.2 Safety Instructions
 The device must only be used within the electric, hydraulic and thermal
limits specified in the data sheet.
 Inductive loads can cause contact burns or fuse the contacts. Preventative
measures must be implemented by the customer, e.g., through use of
suitable RC elements.
 When using the version with ZF 1979 (oil and grease-free), take care to
avoid recontamination of surfaces that are in contact with media, right
through from opening the packaging to completed installation. Generally,
no liability will be assumed for oil and grease-free version.
 High quality stainless-steel sensor parts in contact with media enable the
devices to be used with a variety of media. However, a chemical
resistance test MUST be carried out before selection.
 Use with acids and other aggressive media, such as hydrofluoric acid,
copper chloride, aqua regia or hydrogen peroxide, is not permitted.
 Use in systems with unstable gases and liquids such as hydrogen cyanide,
dissolved acetylene or NOx is not permitted.
 Devices must be protected from solar radiation and rain.
 Pressure switches are precision devices which are calibrated in the
factory. For this reason, never open the device and do not change the
adjustment of the varnished calibration screws.
 Prevent excessive vibrations from reaching the pressure switch, e.g., with
mechanical isolation or other vibration damping measures.
 Heavily contaminated media can clog the sensor and cause errors and/or
malfunction. If the equipment is to be used for this purpose, suitable
chemical seals must be connected.
 Pressure switches and chemical seals form a functional unit and must not
be disconnected from each other in the field.
 Before disassembly (removing the pressure switch from the system), the
device must be disconnected from the power supply and the system must
be emptied. Observe the Accident Prevention Regulations.
 Never use the pressure switches as a climbing aid.
 KOBOLD Messring GmbH accepts no liability for non-compliance.

SCH
SCH K03/0320 page 5
5. Mechanical Connection
Installation
Install directly on the pipeline (pressure gauge connection G 1/2) or with 2 screws
(4 mm) surface mounting. Tighten only on the hexagonal of the pressure
connection, never use the housing or plug for fixing.
Connection
The differential Pressure Switches SCH- DDCM have 2x G 1/4 internal thread
connections. Connect the high and the low pressure according to the marks.
(+) = high pressure
(-) = low pressure
When connecting attention should be paid to the marks.
External thread G 1/2
(Pressure gauge
connection)
When using flat seals,
turn insert the centring
screw.
Internal thread G 1/4
(Remove the centering peg )
In gas application internal
thread only up to 4 bar
permissible. Use flat gasket ring
for higher pressure.

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page 6 SCH K03/0320
6. Electrical Connection
 Ensure that the power is disconnected during connection of the cable.
 Wiring is on the angled plug.
 The cable outlet can be in any of 4 positions, which are at 90° in relation to
each other.
 Remove screw
 Insert the screw driver in the slot and press downwards.
 On devices with terminal connection housing the terminal board is available
after removing the terminal box lid.
Attention! The Pressure Switches are precision instruments, set and
adjusted at the factory. Do not open the device or re-set the
varnished adjustment screw. This would alter the switching points
and resetting would be necessary.
With rising pressure:
3-1 opens, 3-2 closes
With falling pressure:
3-2 opens, 3-1 closes

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SCH K03/0320 page 7
7. Setting the Switching Pressure
7.1 Setting the Switching Pressure
with Plug Connection
The switching pressure is set using the
setting spindle. Before setting loosen the
locking screw located above the scale by
approx. 2 turns and tighten it again after
setting. The scale value corresponds to the
upper switching point (for rising pressure).
The lower switching point (for falling
pressure) is lower by the value of switching
difference. The scale serves only as an
estimated value scale, a pressure gauge is
required for accurate settings.
On the pressure switch housing, the setting
screw is accessible after removing the cover.
Attention: Switch off voltage !
Switching pressure
 turn to the right: lowers switch point
 turn to the left: raises switch point
7.2 Setting the Switching Point
The switching point can be set within the range given in the datasheet by using a
screwdriver on the setting spindle. Additionally you should remove the terminal
board casing (with 4 hexagon screw M 4). The affixing screw on the front end
(above the scale) has to be removed and should be reattached after setting the
switching point.
Turning the setting spindle clockwise gives a lower switching point, turning
anticlockwise gives a higher switching point.
The scale should be used as a guide, for more exact settings you should use a
manometer.

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page 8 SCH K03/0320
Serial Numbers
All switch units and their respective terminal board casings are marked with a
serial number. When installing you should ensure that the terminal board casings
do not get mixed up.
Note: When installing the Ex switch units and setting them up for
operation you should comply with the recognised rules and
guidelines for installations in Ex-areas.
7.3 Setting Switching Difference (only model V)
One spindle each is available for setting the switching pressure and the switching
difference. Both spindles are arranged concentrically. The outer spindle, with
larger diameter, adjusts the lower switching point; the switching difference, and
thus the upper switching point, is changed with the small central screw located
internally.
The action direction is indicated by the arrow direction.
Setting sequence
 Adjust the lower switching point (with decreasing pressure), with outer spindle,
according to scale or pressure gauge.
 Adjust the switching difference (with increasing pressure), with small, internal
central screw, results in setting the upper switching point.
When the switching difference is changed, the lower switch-off point remains
unchanged, the upper switching point is shifted by the switching difference.
xd= switching difference
(hysteresis)
SP= switching point
RSP= switch back point

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SCH K03/0320 page 9
8. Special Functions
8.1 Maximum- and Minimum Pressure Limiter (-205 and -206)
Instead of a microswitch with automatic reset, a "bistable" microswitch is installed
in the limiters. When the pressure reaches the value set on the scale, the
microswitch switches over and remains in the position.
 Unlocking
The catch can be released by pressing in the unlocking
button (marked on the scale side of the switching device by
a red dot.) The limiter can not be unlocked until the
pressure has decreased by a certain amount or, in the case
of interlocking at the lower switching point, is increased
again. Depending on the version, the interlock can be
effective for a rising value (max. limiter ...-205) or for a
falling value (min. limiter ...206).
8.2 Two Stage Pressure Switches (- 307 and - 217)
A switch-unit, with two microswitches both with single-poled changeover, forms
part of the basic equipment for each two-stage Pressure Switch.
 The first switch I monitors lower pressure
 The second switch II monitors higher pressure.
 It should be noted that the switching differentials of the individual
microswitches cannot be exactly identical because of their component
tolerances.
 The switching interval of both microswitches is the interval (in bar or mbar)
between the switching points of both microswitches.
Applies for all variations:
Changes to the setting spindle, to the setting of switching pressure, do not lead to
changes in the switching intervals as the switching points are adjusted corre-
spondingly. The switching differential of the individual microswitches corresponds
to the switching differences listed under basic equipment.
Minimum pressure limiter Maximum pressure limite
r

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page 10 SCH K03/0320
The switching differential cannot be set for individual microswitches in two-
stage Pressure Switches.
 Two stage Pressure Switch - 307
The switching interval between both switches is
set according to the customer’s requirements.
With increasing pressure first microswitch I
(terminal connection 1-3) and then
microswitch II (terminal connection 4-6) is
activated.
 Two stage Pressure Switch - 217
as in -209 however the switching interval can be set within given limits.
 Setting wheel I CW-reduce switching point at
microswitch I
 Setting wheel II CCW-raise switching point at
microswitch II
Setting wheels I and II have an internal stop to ensure that the microswitches
cannot be adjusted past their effective range.
Attention: Note the sticker besides the plug connection of Pressure
Switch.

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SCH K03/0320 page 11
8.3 Switching Interval and Schematic Wiring Diagrams
Switching interval of two stage Pressure Switch (Option 217, 307)
Min. switchin
g
interval Max. switchin
g
interval
(
avera
g
e value
)
Model Factory-set
Schematic wiring
diagram
A1/A3/B2/B4
C1/C3/D2/D4
+ Option 307
Schematic wiring
diagram
A2/A4/C2/C4
Schematic wiring
diagram
B1/B3/D1/D3
DCM 06 25 mbar 165 mbar 190 mbar 140 mbar
DCM 025 20 mbar 140 mbar 160 mbar 120 mbar
DCM 1 40 mbar 240 mbar 280 mbar 200 mbar
DCM 6/DNM 6 0.15 bar 0.95 bar 1.2 bar 0.8 bar
DCM 10 0.25 bar 1.6 bar 1.85 bar 1.35 bar
DCM 16 0.3 bar 2.0 bar 2.3 bar 1.7 bar
DCM 40 0.9 bar 6.0 bar 6.9 bar 5.1 bar
DCM 63 1.3 bar 8.5 bar 9.8 bar 7.2 bar
DDCM 1 0.09 bar 0.55 bar 0.64 bar 0.46 bar
DDCM 6 0.14 bar 0.94 bar 1.08 bar 0.8 bar
DNM 06 40 mbar 240 mbar 270 mbar 200 mbar
DNM 025 35 mbar 215 mbar 240 mbar 180 mbar
V
CM 095 40 mbar 300 mbar 340 mbar 260 mbar
V
CM 101 40 mbar 260 mbar 300 mbar 220 mbar
V
CM 301 20 mbar 100 mbar 120 mbar 80 mbar
V
NM 111 50 mbar 310 mbar 360 mbar 260 mbar
Order reference for Extrafunction ZF217
Schematic
wiring
diagram Switchgear Orderposition Extratext
A1 A DCM6-217A-S Schematic wiring diagram A1
A2 C DCM6-217C-S Schematic wiring diagram A2
A3 C DCM6-217C-S Schematic wiring diagram A3
A4 A DCM6-217A-S Schematic wiring diagram A4
B1 B DCM6-217B-S Schematic wiring diagram B1
B2 D DCM6-217D-S Schematic wiring diagram B2
B3 D DCM6-217D-S Schematic wiring diagram B3
B4 B DCM6-217B-S Schematic wiring diagram B4
C1 B DCM6-217B-S Schematic wiring diagram C1
C2 D DCM6-217D-S Schematic wiring diagram C2
C3 D DCM6-217D-S Schematic wiring diagram C3
C4 B DCM6-217B-S Schematic wiring diagram C4
D1 A DCM6-217A-S Schematic wiring diagram D1
D2 C DCM6-217C-S Schematic wiring diagram D2
D3 C DCM6-217C-S Schematic wiring diagram D3
D4 A DCM6-217A-S Schematic wiring diagram D4

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page 12 SCH K03/0320
Schematic wiring diagram for Option 217

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SCH K03/0320 page 13
Adjustment
The addition of the adjustment with setting wheels I and II provides the switching
interval between the two microswitches. Changes made at the setpoint spindle do
not affect the switching interval; the switching internal remains constant over the
entire adjustment range of the spindle, the two switching points being displaced
up or down in parallel.
1) Turn setting wheel I fully CCW. Turn setting wheel II fully CW. The lowest
switching interval is adjusted.
2) Set setpoint spindle S to a value on the scale which is central between the
required top and required bottom switching point.
3) With pressure applied, set bottom switching point with setting wheel I (a1)
4) With setting wheel II, proceed as under 3. above to set top switching point
(a2).
5) If the required top and bottom switching point cannot be obtained, adjust set-
point spindle S in the necessary direction and repeat setting as per 3. and 4.
above.
Example:
Desired switching points: 3,8 and 3,2 bar
Adjustment according point 2: S=3,5 bar
 Set bottom switching point (3,2 bar) with
setting wheel I (turn to the right)
 Set top switching point (3,8 bar) with setting
wheel II (turn to the left).
8.4 Gold Plated Contacts (-213)
Gold plated contacts are used exclusively in the low voltage range in order to
keep the transit resistance at the contact low. Switch points see standard types.
Switching capacity: min. 4 mA, 5 VDC ; max. 100 mA, 24 VDC.
At higher voltages and currents the gold layer on the contacts will be damaged.
8.5 SCH-EX- (EEx-d-Version)
Pressure switches in Ex version can be delivered only in a design tested by the
IBExU.
Versions and additional functions are basically not possible.

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page 14 SCH K03/0320
9. Technical Information
Switch: single -pole changeover
Switching capacity: 8 (5) A, 250 VAC
SCH-EX-...:
3 A, 250 VAC; 2 A, 250 VAC (inductive),
0,1 A, 250 VDC, 3 A, 24 VDC
Protection: IP 54 with plug connection
IP 65 (for terminal connection)
Installation position: preferable vertical
Max. medium temperature: 70 °C, higher medium temperatures are possible
if the above limiting values at the switching
devices are not exceeded by suitable measures
(e.g. syphon).
Max. ambient temperature: -25...+70 °C (-25...+60 °C for SCH-DGM)
At ambient temperatures below 0°C ensure that
no water condensation can arise in the sensor
and in the switching device.
Switching difference: see data-sheet
Switching device: Robust housing made of sea-water resistance
aluminium die casting.
9.1 Technical Information SCH-Ex units
Type of Ex-protection: II 2 G Ex de IIC T6 Gb
II 1/2D Ex ta/tb IIIC T80 °C Da/Db
Compatible for Ex-Zones: 1 and 2 (gas)
21 and 22 (dust on housing cover)
20, 21 and 22 (dust on sensor)
Form of protection: IP 65 (vertical position)
Ambient temperature: –20 to +60 °C
Max. temperature
at Pressure Switch: 60 °C
Cable type: M16 x 1.5 only for fixed installation
Switching difference: not adjustable, approximate values
see data sheet
Fitting position: vertically upwards
Earthing connection / potential equalisation
Max. cross section of the cable: 4 mm2, external on the outside of the
switching unit.
10. Order Codes
See data sheet.

SCH
SCH K03/0320 page 15
11. EU Declaration of Conformance
We, KOBOLD Messring GmbH, Hofheim-Ts, Germany, declare under our sole
responsibility that the product:
Pressure Switch Model: SCH-...
to which this declaration relates is in conformity with the standards noted below:
EN 60335-1 (IEC 60335-1) Safety of household and similar
Electrical appliances.
EN 60335-1:1994 (IEC 60335-1:1994) Part 1: General requirements
following the provision of European Directives:
2014/35/EU Low Voltage Directive
2011/65/EU RoHS (category 9)
2015/863/EU Delegated Directive (RoHS III)
additionally for model: SCH-EX-…
94/9/EG EX-Protection Directive (Equipment and Protective systems intended
for use in a potentially Explosive Atmospheres )
Test certificate no.: IBExU13ATEX1125
Notified body: IBExU Institut für Sicherheitstechnik GmbH
Type examination certificate: IBExU13ATEX1125
Test specifications: EN 60079-0:2012
EN 60079-1:2007
EN 60079-7:2007
EN 60079-31:2009
Notified body: IBExU Institut für Sicherheitstechnik GmbH
Identification:
SCH-Ex II 2G Ex d e IIC T6 Gb
II 1/2D Ex ta/tb IIIC T80°C Da/Db
Hofheim, 06 Aug 2019
H. Peters M. Wenzel
General Manager Proxy Holder

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page 16 SCH K03/0320
12. Examination Certificate

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SCH K03/0320 page 17

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