40
sProtection Class:
IP 54
Mechanical pressure switches
Liquids and gases
This universal pressure switch can be used in
general mechanical engineering and the printing
machine industry, as well as in pneumatics and
hydraulics.
SIL 2 according IEC 61508-2
DCM/DNM
Pressure switches and pressure monitors for overpressure
DCM25
Switching 250 VAC 250 VDC 24 VDC
capacity (ohm) (ind) (ohm) (ohm)
Normal 8 A 5 A 0.3 A 8 A
Type Setting range Switching Max. Materials in- Dimen-
differential permissible contact with sioned
(mean values) pressure medium drawing
Switching differential not adjustable page 25 + 26
DCM4016 1…16 mbar 2 mbar 1 bar Perbunan 1 + 11
DCM4025 4…25 mbar 2 mbar 1 bar + 1.4301
DCM1000 10…100 mbar 12 mbar 10 bar Perbunan + MS 1 + 10
DCM025 0.04…0.25 bar 0.03 bar 6 bar Cu + Ms
DCM06 0.1…0,6 bar 0.04 bar 6 bar Cu + Ms 1 + 14
DCM1 0.2…1,6 bar 0.04 bar 6 bar Cu + Ms
DNM025 0.04…0.25 bar 0.03 bar 6 bar 1 + 15
DCM506 15…60 mbar 10 mbar 12 bar 1 + 12
DCM3 0.2…2.5 bar 0.1 bar 16 bar Sensor
DCM6 0.5…6 bar 0.15 bar 16 bar housing
DCM625 0.5…6 bar 0.25 bar 25 bar 1.4104
DCM10 1…10 bar 0,3 bar 25 bar +
DCM16 3…16 bar 0.5 bar 25 bar Pressure
DCM25 4…25 bar 1.0 bar 60 bar bellow
DCM40 8…40 bar 1.3 bar 60 bar 1.4571
DCM63 16…63 bar 2.0 bar 130 bar
Switching differential adjustable
DCMV025 0.04…0.25 bar 0.03…0.4 bar 6 bar
DCMV06 0.1…0.6 bar 0.04…0.5 bar 6 bar Cu + Ms 1 + 14
DCMV1 0.2…1.6 bar 0.07…0.55 bar 6 bar
DCMV3 0.2…2.5 bar 0.15…1.5 bar 16 bar Sensor
DCMV6 0.5…6 bar 0.25…2.0 bar 16 bar housing
DCMV625 0.5…6 bar 0.25…2.0 bar 25 bar 1.4104
DCMV10 1…10 bar 0.5…2.8 bar 25 bar +
DCMV16 3…16 bar 0.7…3.5 bar 25 bar Pressure
DCMV25 4…25 bar 1.3…6.0 bar 60 bar bellow
DCMV40 8…40 bar 2.6…6.6 bar 60 bar 1.4571 1 + 16
DCMV63 16…63 bar 3.0…10 bar 130 bar
For smaller pressure ranges see also VCM, DGM, HCD and DPS sheets.
For additional functions refer page 30 – 32.
Calibration
The DCM series is calibrated for falling pressure. This means that the adjustable switching pressure on
the scale corresponds to the switching point at falling pressure. The reset point is higher by the amount
of the switching differential. (See also page 27, 1. Calibration at lower switching point).
1 + 18
1 + 18
1 + 17
1 + 17
1 + 16
-DCM/DNM
see page 65
Technical data
Pressure connection
External thread G 1/2 (pressure gauge
connection) according to DIN 16 288 and inter-
nal thread G 1/4 according to ISO 228 Part 1.
Switching device
Robust housing (200) made of seawater-
resistant diecast aluminium GD Al Si 12.
Protection class
IP 54, in vertical position.
Pressure sensor materials
DNM025…DCM63 Metal bellows: 1.4571
Sensor housing: 1.4104
DCM025 – DCM 1 Metal bellows: Cu Sensor
housing: Cu + Ms
DCM4016/ Diaphragm: Perbunan
DCM4025 Sensor housing: 1.4301
DCM1000 Diaphragm: Perbunan
Sensor housing: Brass
Mounting position
Vertically upright and horizontal. DCM4016
and 4025 vertically upright.
Ambient temp. at switching device
–25…+70 °C, except: DCM4016,
4025, 1000: –15…+60 °C
Max. medium temperature
The maximum medium temperature at the
pressure sensor must not exceed the
permitted ambient temperature at the
switching device. Temperatures may reach
85°C for short periods). Higher medium
temperatures are possible provided the above
limit values for the switching device are
ensured by suitable measures (e.g. siphon).
Mounting
Directly on the pressure line (pressure
gauge connection) or on a flat surface with two
4 mm Ø screws.
Switching pressure
Adjustable from outside with screwdriver.
Switching differential
Not adjustable with DCM and types. Adjustable
from outside with DCMV types. For values see
Product Summary.
Contact arrangement
Single-pole changeover switch.
19
Accessories Pressure switchesPressure transmittersThermostatsTemperature sensorsFlow monitorsSolenoid valves
Mechanical pressure switches
Technical features/Advantages
Mechanical pressure switches
Technical features / Advantages
Wall mounting
or directly on the pressure line
Switching element (microswitch)
Lead sealable setpoint adjustment
Setting spindle locking element
Terminal connection
or plug connection to
DIN EN175301 Form A
Stainless steel sensor housing
Stainless steel bellows
with internal stop
Pressure connection
G 1/2" external
G 1/4" internal
Centring pin
Diecast aluminium housing
IP 54 or IP 65
version also available
20 Mechanical pressure switches
Definitions
Definitions
Pressure data
Overpressure Pressure over the relevant atmospheric pressure. The reference point is
atmospheric pressure.
Vacuum Pressure under the relevant atmospheric pressure. The reference point is
atmospheric pressure.
Absolute pressure Overpressure relative to absolute vacuum.
Differential pressure Difference in pressure between 2 pressure measuring points.
Relative pressure Overpressure or vacuum relative to atmospheric pressure.
Pressure data in all FEMA documents refers to relative pressure.
That is to say, it concerns pressure differentials relative to atmospheric pressure.
Overpressures have a positive sign, vacuums a negative sign.
Permissible working pressure (maximum permissible pressure)
The maximum working pressure is defined as the upper limit at which the operation, switching reliability
and water tightness are in no way impaired (for values see Product summary).
Bursting pressure (test pressure)
Type-tested products undergo a pressure test certified by TÜV affirming that the bursting pressure
reaches at least the values mentioned in the Product summary. During the pressure tests the measuring
bellows are permanently deformed, but the pressurized parts do not leak or burst. The bursting pressure
is usually a multiple of the permissible working pressure.
Setting range
Pressure range in which the cutoff pressure can be set with the setting spindle.
Pressure units
Important:
All pressure data refers to overpressures or vacuums relative to atmospheric pressure.
Overpressures have a positive sign, vacuums a negative sign.
Unit bar mbar Pa kPa MPa (psi) Ib/m2
1 bar 1 1000 105 100 0.1 14.5
1 mbar 0.001 1 100 0.1 10-4 0.0145
1 Pa 10-5 0.01 1 0.001 10-6 1.45 · 10-4
1 kPa 0,01 10 1000 1 0.001 0,145
1 MPa 10 104 106 1000 1 145
In FEMA documents pressures are stated in bar or mbar.
Pressure data for a pressure
switchbased on the example
of DWR625:
Setting range: 0.5-6 bar
Perm. working pressure: 20 bar
Bursting pressure: >100 bar
21
Accessories Pressure switchesPressure transmittersThermostatsTemperature sensorsFlow monitorsSolenoid valves
Mechanical pressure switches
Definitions
Definitions
Switching differential
The switching differential (hysteresis) is the difference in pressure between the switching point (SP)
and the reset point (RSP) of a pressure switch. Switching differential tolerances occur due to
tolerances in the microswitches, springs and pressure bellows. Therefore the data in the product
summaries always refers to average values. In the case of limiter functions the switching differential
has no significance, as one is only interested in the switching point at which cutoff occurs, not the
reset point. For a controller function, i. e. in the case of pressure switches used to switch a burner,
pump etc. on and off, a pressure switch with an adjustable switching differential should be
chosen. The switching frequency of the burner or pump can be varied by changing the switching
differential.
Adjustable switching differential/ calibration
In the case of pressure switches with adjustable switching differential, the hysteresis can be set within
the specified limits. The switching point (SP) and reset point (RSP) are precisely definable. When
setting the pressure switch, the switching differential situation and the type of factory calibration must
be taken into account. Some pressure switches (e.g. minimum pressure monitors of the DCM series)
are calibrated under "falling" pressure, i.e. switching under falling pressure takes place at the scale
value with the switching differential being above it. The device switches back at scale value +
switching differential. If the pressure switch is calibrated under rising pressure, switching takes place
at the scale value and the device switches back at scale value - switching differential (see direction of
action). The calibration method is indicated in the data sheets.
Direction of action
In principle, any pressure switch can be used for both maximum pressure and minimum pressure
monitoring. This excludes pressure limiters, whose direction of action (maximum or minimum) is
predefined. The only thing to remember is that the scale reading may deviate by the amount of the
switching differential. See example at bottom left: The scale value is 2.8 bar.
Maximum pressure monitoring
With rising pressure, switching takes place once the preset switching pressure is reached (SP).
The reset point (RSP) is lower by the amount of the switching differential.
Minimum pressure monitoring
With falling pressure, switching takes place once the preset switching pressure is reached (SP).
The reset point (RSP) is higher by the amount of the switching differential.
Direction of action in vacuum range
It is particularly important to define the direction of action in the vacuum range.
Rising does not mean a rising vacuum, but rising pressure (as viewed from absolute "0"). "Falling"
pressure means a rising vacuum.
For example: Vacuum switch set to -0.6 bar falling means: Switching (SP) takes place under falling
pressure (rising vacuum) at -0.6 bar. The reset point is higher by the amount of the switching
differential (e.g. at -0.55 bar).
Setting a pressure switch
To define the switching point of a pressure switch exactly, it is necessary to determine the direction of
action in addition to the pressure. "Rising" means that switching takes place at the set value when the
pressure rises.
The reset point is then lower by the amount of the switching differential. "Falling" means exactly the
opposite.
Please note when specifying the setting of a pressure switch:
In addition to the switching point it is also necessary to specify the direction of action (falling or rising).
Example for selection of a pressure switch:
A pump is to be turned on at 2.8 bar and off again at 4.2 bar.
Chosen type: DCMV6 according to data sheet DCM. Setting: Scale pointer to 2.8 bar (lower switching
point). Switching differential to 1.4 bar (set according to pressure gauge).
Cutoff point: 2.8 bar +1.4 bar = 4.2 bar.
Maximum pressure monitoring
RSP = SP – xd
Minimum pressure monitoring
RSP = SP + xd
22 Mechanical pressure switches
General description
Operating mode
The pressure prevailing in the sensor housing (1) acts on the measuring bellows (2). Changes in
pres sure lead to movements of the measuring bellows (2) which are transmitted via a thrust pin
(4) to the connecting bridge (5). The connecting bridge is frictionlessly mounted on hardened points
(6). When the pressure rises the connecting bridge (5) moves upwards and operates the microswitch
(7). A counter-force is provided by the spring (8), whose pre-tension can be modified by the adjusting
screw (9) (switching point adjustment). Turning the setting spindle (9) moves the running nut (10) and
modifies the pre-tension of the spring (8). The screw (11) is used to calibrate the microswitch in the
factory. The counter pressure spring (12) ensures stable switching behaviour, even at low setting values.
Pressure sensors
Apart from a few exceptions in the low-pressure range, all pressure sensors have measuring bellows,
some made of copper alloy, but the majority of high-quality stainless steel. Measured on the basis of
permitted values, the measuring bellows are exposed to a minimal load and perform only a small lifting
movement. This results in a long service life with little switching point drift and high operating reliability.
Furthermore, the stroke of the bellows is limited by an internal stop so that the forces resulting from
the overpressure cannot be transmitted to the switching device. The parts of the sensor in contact with
the medium are welded together without filler metals. The sensors contain no seals. Copper bellows,
which are used only for low pressure ranges, are soldered to the sensor housing. The sensor housing
and all parts of the sensor in contact with the medium can also be made entirely from stainless steel
1.4571 (DNS series). Precise material data can be found in the individual data sheets.
Pressure connection
The pressure connection on all pressure switches is executed in accordance with DIN 16288 (pressure
gauge connection G 1/2A). If desired, the connection can also be made with a G 1/4 internal thread in
accordance with ISO 228 Part 1.
Maximum screw-in depth on the G 1/4 internal thread = 9 mm.
Centring pin
In the case of connection to the G 1/2 external thread with seal in the thread (i.e. without the usual
stationary seal on the pressure gauge connection), the accompanying centring pin is not needed.
Differential pressure switches have 2 pressure connections (max. and min.), each of which are to be
connected to a G 1/4 internal thread.
1 = Pressure connection
2 = Measuring bellows
3 = Sensor housing
4 = Thrust pin
5 = Connecting bridge
6 = Pivot points
7 = Microswitch or other
switching elements
8 = Setting spring
9 = Setting spindle (switching
point adjustment)
10 = Running nut (switching point
indicator)
11 = Microswitch calibration
screw (factory calibration)
12 = Counter pressure spring
23
Accessories Pressure switchesPressure transmittersThermostatsTemperature sensorsFlow monitorsSolenoid valves
Mechanical pressure switches
Principal technical data
Principal technical data
Valid for all pressure switches of the DCM, DNM, DWAM, DWAMV, SDBAM, VCM, VNM, DNM, DWR, DGM,
DNS and DDCM series that have a microswitch. The technical data of type-tested units may differ slightly
(please refer to particular type sheet).
Standard version
Plug connection Terminal connection
…200 …300
Switch housing
Pressure connection
Switching function and
connection scheme
(applies only to version
with microswitch)
Switching capacity
(for microswitches with
a silver contact)
Mounting position
Protection class
(in vertical position)
Electrical connection
Cabel entry
Ambient temperature
Switching point
Hysteresis
Medium temperature
Relative humidity
Vacuum
Repetition accuracy
of switching points
Vibration resistance
Mechanical durability
(pressure sensor)
Electronical durability
(microswitch)
Isolation values
Oil and grease-free
Diecast aluminium GDAISi 12
G 1/2" external thread (pressure gauge
connection) and G 1/4" internal thread.
1/4" internal thread for DDCM differential
pressure switches
Floating changeover contact.
With rising pressure
single pole switching
from 3–1 to 3–2.
8 A at 250 VAC
5 A at 250 VAC inductive
8 A at 24 VDC
0.3 A at 250 VDC
min. 10 mA, 12 VDC
Preferably vertical (see technical data sheet)
IP 54
Plug connection
Pg 11
–25 to +70 °C (exceptions:
DWAM, DWAMV, SDBAM series –20 to +70 °C
DGM and FD series: –25 to +60 °C
DCM4016, 4025, 1000,
VCM4156: –15 to +60 °C)
Adjustable using the setting spindle (for 300 device:
after removing switch housing cover)
Adjustable or not adjustable
(see Product Summary)
Max. 70 °C, briefly 85 °C
15 to 95 % (non-condensing)
Diecast aluminium GDAISi 12
G 1/2" external thread (pressure gauge
connection) and G 1/4" internal thread.
1/4" internal thread for DDCM differential
pressure switches
Floating changeover contact.
With rising pressure
single pole switching
from 3–1 to 3–2
3 A at 250 VAC
2 A at 250 VAC inductive
3 A at 24 VDC
0.1 A at 250 VDC
min. 2 mA, 24 VDC
Vertical
IP 65
Terminal connection
M 16 x 1.5
–25 to +70 °C (exceptions:
DWAM, DWAMV, SDBAM series –20 to +70 °C
DGM and FD series: –25 to +60 °C
DCM4016, 4025, 1000,
VCM4156: –15 to +60 °C)
Adjustable using the setting spindle once the
switch housing cover is removed
Adjustable or not adjustable
(see Product Summary)
Max. 70 °C, briefly 85 °C
15 to 95 % (non-condensing)
Higher medium temperatures are possible provided the above limits for the switching device are
ensured by suitable measures (e.g. siphon). All pressure switches can operate under vacuum.
This will not damage the device (exception DCM1000).
< 1 % of the working range (for pressure ranges > 1 bar).
No significant deviations up to 4 g.
With sinusoidal pressure application and room temperature, 10 x 106 switching cycles. The expected life
depends to a very large extent on the type of pressure application, therefore this figure can serve only as
a rough estimate. With pulsating pressure or pressure impacts in hydraulic systems, pressure surge
reduction is recommended.
100.000 switching cycles at nominal current 8 A, 250 VAC.
A reduced contact load increases the number of possible switching cycles.
Overvoltage category III, contamination class 3, reference surge voltage 4000 V.
Conformity to DIN VDE 0110 is confirmed.
The parts of all pressure switches in contact with the medium are oil and grease-free
(except the HCD…and DPS…series). The sensors are hermetically sealed and contain no seals
(also see ZF1979, special packing).
24 Mechanical pressure switches
Principal technical data
Principal technical data
Valid for all pressure of the DCM, VCM, DNM, DWR, DGM, DNS and DDCM series that have a microswitch.
The technical data of type-tested units may differ slightly (please refer to particular type sheet).
Ex-i-version
…500
Switch housing
Pressure connection
Switching function and
connection scheme
(applies only to version
with microswitch)
Switching capacity
Mounting position
Protection class
(in vertical position)
Explosion protection
Code
EC Type Examination
Certificate Number
Electrical connection
Cabel entry
Ambient temperature
Medium temperature
Relative humidity
Switching point
Hysteresis
Vacuum
Repetition accuracy
of switching points
Vibration resistance
Mechanical durability
(pressure sensor)
Electronical durability
(microswitch)
Isolation values
Oil and grease-free
Diecast aluminium GDAISi 12
G 1/2" external thread (pressure gauge
connection) and G 1/4" internal thread.
1/4" internal thread for DDCM differential
pressure switches
Floating changeover contact.
With rising pressure
single pole switching
from 3–1 to 3–2
max.: 100mA, 24VDC
min.: 2mA, 5VDC
Vertical
IP 65
II 1/2G Ex ia IIC T6 Ga/Gb
II 1/2D Ex ia IIIC T80 °C
IBExU12ATEX1040
Terminal connection
M 16 x 1.5
–25 to +60 °C (exceptions:
DWAM, DWAMV, SDBAM series –20 to +60 °C
DGM and FD series: –25 to +60 °C
DCM4016, 4025, 1000, VCM4156: –15 to +60 °C)
Max. 60 °C
15 to 95 % (non-condensing)
After removing switch housing cover
Not adjustable
Diecast aluminium GDAISi 12
G 1/2" external thread (pressure gauge connection)
and G 1/4" internal thread.
1/4" internal thread for DDCM differential pressure
switches
Floating changeover contact.
With rising pressure
single pole switching
from 3–1 to 3–2
3 A at 250 VAC
2 A at 250 VAC inductive
3 A at 24 VDC
0.1 A at 250 VDC
min. 2 mA, 24 VDC
Vertical
IP 65
II 2G Ex d e IIC T6 Gb
II 1/2D Ex ta/tb IIIC T80 °C Da/Db
IBExU12ATEX1040
Terminal connection
M 16 x 1.5
–20 to +60 °C
Max. 60 °C
15 to 95 % (non-condensing)
After removing switch housing cover
Not adjustable
Higher medium temperatures are possible provided the above limits for the switching device are
ensured by suitable measures (e.g. siphon). All pressure switches can operate under vacuum.
This will not damage the device.
< 1 % of the working range (for pressure ranges > 1 bar).
No significant deviations up to 4 g.
With sinusoidal pressure application and room temperature, 10 x 106 switching cycles. The expected life
depends to a very large extent on the type of pressure application, therefore this figure can serve only as
a rough estimate. With pulsating pressure or pressure impacts in hydraulic systems, pressure surge
reduction is recommended.
100.000 switching cycles at nominal current 8 A, 250 VAC.
A reduced contact load increases the number of possible switching cycles.
Overvoltage category III, contamination class 3, reference surge voltage 4000 V.
Conformity to DIN VDE 0110 is confirmed.
The parts of all pressure switches in contact with the medium are oil and grease-free
(except the HCD…and DPS…series). The sensors are hermetically sealed and contain no seals
(also see ZF1979, special packing).
version (Ex-d)
…700
25
Accessories Pressure switchesPressure transmittersThermostatsTemperature sensorsFlow monitorsSolenoid valves
Mechanical pressure switches
Dimensioned drawings
Dimensioned drawings of switch housings (mm)
Housing 200 (plug connection)
1Housing 300 (terminal connection)
2
Housing 500 (terminal connection Ex-i) Housing 700 (terminal connection Ex-d)
3 4
10 11
Dimensioned drawings of pressure sensors (mm)
hex24
26
12
hex Dimensioned hex
drawing
16 22
17 24
18 30
19 32
13
16
20
19
Mechanical pressure switches
Dimensioned drawings
Dimensioned drawings of pressure sensors (mm)
hex22
hex22
hex41
1514
hex41
21
27
Accessories Pressure switchesPressure transmittersThermostatsTemperature sensorsFlow monitorsSolenoid valves
Mechanical pressure switches
Setting instructions
Setting instructions
Factory calibration of pressure switches
In view of tolerances in the characteristics of sensors and springs, and due to friction in the switching
kinematics, slight discrepancies between the setting value and the switching point are unavoidable.
The pressure switches are therefore calibrated in the factory in such a way that the setpoint
adjustment and the actual switching pressure correspond as closely as possible in the middle of
the range. Possible deviations are equally distributed on both sides.
The device is calibrated either for falling pressure (calibration at lower switching point) or for rising
pressure (calibration at higher switching point), depending on the principal application of the type
series in question.
Where the pressure switch is used at other than the basic calibration, the actual switching point
moves relative to the set switching point by the value of the average switching differential. As FEMA
pressure switches have very small switching differentials, the customer can ignore this where the
switching pressure is set only roughly. If a very precise switching point is needed, this must be
calibrated and checked in accordance with normal practice using a pressure gauge.
1. Calibration at lower switching point 2. Calibration at upper switching point
Setpoint xS corresponds to the lower switching Setpoint xS corresponds to the upper switching
point, the upper switching point xO is higher point, the lower switching point xU is lower
by the amount of the switching differential xd. by the amount of the switching differential xd.
The chosen calibration type is indicated in the technical data for the relevant type series.
Setting switching pressures
Prior to adjustment, the securing pin above the scale must be loosened by not more than 2 turns and
retightened after setting. The switching pressure is set via the spindle. The set switching pressure is
shown by the scale.
To set the switching points accurately it is necessary to use a pressure gauge.
Changing the switching differential (only for switching device with suffix "V", ZF203)
By means of setscrew within the spindle. The lower switching point is not changed by the
differential adjustment; only the upper switching point is shifted by the differential. One turn of
the differential screw changes the switching differential by about 1/4 of the total differential range.
The switching differential is the hysteresis, i.e. the difference in pressure between the switching
point and the reset point.
Lead sealing of setting spindle (for plug connection housing 200 only)
The setting spindle for setting the desired value and switching differential can be covered and
sealed with sealing parts available as accessories (type designation: P2) consisting of a seal plate
and capstan screw. The sealing parts may be fitted subsequently. The painted calibration screws
are likewise covered.
Clockwise:
lower switching
pressure
Anticlockwise:
higher switching
pressure
Clockwise:
greater diffe-
rence
Anticlockwise:
smaller diffe-
rence
Direction of action of setting
spindle
With pressure switches from
the DWAMV and DWR...-203
series, the direction of action of
the differential screw is
reversed.
28 Mechanical pressure switches
Pressure switch with locking of switching state (reclosing lockout)
Pressure switch with switching state
locking (reclosing lockout)
In the case of limiter functions, the switching state must be retained and locked, and it may be unlocked
and the system restarted only after the cause of the safety shutdown has been eliminated. There are two
ways of doing this:
1. Mechanical locking inside the pressure switch
Instead of a microswitch with automatic reset, limiters contain a "bi-stable" microswitch. If the pressure
reaches the value set on the scale, the microswitch trips over and remains in this position. The lock can
be released by pressing the unlocking button (identified by a red dot on the scale side of the switching
device). The lock can operate with rising or falling pressure, depending on the version. The device can
only be unlocked when the pressure has been reduced (or increased) by the amount of the
predefined switching differential. When selecting a pressure limiter, it is necessary to distinguish
between maximum and minimum pressure monitoring. Ex-d versions cannot be equipped with internal
locking.
Maximum pressure limitation Minimum pressure limitation
Switching and interlock- Switching and interlocking
ing with rising pressure. with falling pressure.
Additional function Additional function
ZF205. ZF206.
Connection of control Connection of control
current circuit to current circuit to
terminals 1 and 3. terminals 2 and 3.
2. External electrical interlock in the control cabinet (suggested circuits)
A pressure monitor (microswitch with automatic reset) can also be used as a limiter if an electrical
interlock is added. For pressure limitation in steam and hot water boilers, an external interlock is only
permitted if it has been ascertained that the pressure monitor is "of special construction".
Maximum pressure limitation Minimum pressure limitation
with external interlock with external interlock
Where the above lock circuit is used, the requirements of DIN 57 116/VDE 0116 are met if the electrical
equipment (such as contactors or relays) of the external interlock circuit satisfy VDE 0660 or VDE 0435.
29
Accessories Pressure switchesPressure transmittersThermostatsTemperature sensorsFlow monitorsSolenoid valves
Mechanical pressure switches
Explanation of type designations – type codes
Explanation of type designations –
type codes
The type designations of FEMA pressure switches consist of a combination of letters followed by a
number denoting the setting range. Additional functions and version variants are indicated by an extra
code which is separated from the basic type by a hyphen. Ex versions (explosion protection Ex-d)
are identified by the prefix "Ex" in front of the type designation.
Basic version With additional function Ex version
(based on the example of DCM series)
DCMXXX DCMXXX-YYY Ex-DCMXXX
DCM Series code (e. g. DCM)
XXX Codes for pressure range
YYY Code for additional function
Ex Code for Ex-version
Which additional function fits with which pressure switch?
Plug connection, 200 series
Additional function ZF
Terminal connection, 300/500 series
Additional function ZF
203 213 217 301 307 513 574 575
351 576 577
DCM/VCM •1 • •1 • •1 •
VNM/DNS/VNS • • • • • •
DWAM • • • • •
DDCM • • •
DWR • • • • • •
DGM • • • • •
•available 1 except DCM4016, DCM4025, VCM4156 and DCM1000
Combination of several additional functions not possible!
Ex versions (Ex-d) can only be supplied in basic form.
Additional functions are not possible.
DCMXXX Basic version with plug connection housing
DCMXXX-2... Basic version with plug connection housing
DCMXXX-3... Terminal connection housing (300)
Ex-DCMXXX Ex-d switching device (700)
DCMXXX-5... Ex-ia version (500)
Switch housing version
30 Mechanical pressure switches
Additonal functions/Connecting schemes
Pressure switches and pressure monitors
Additional functions / Connection schemes
Plug connection, Terminal connection, Connection scheme
200 series (IP 54) 300 series (IP 65)
Standard version
(plug connection)
Micro switch, single pole
switching, switching
differential not adjustable
Terminal connection ZF301
housing (300)
Unit with adjustable ZF203
switching differential
Maximum pressure limiter ZF205
with reclosing lockout
Interlocking with
rising pressure
see DWR series
Minimum pressure limiter ZF206
with reclosing lockout
Interlocking with
falling pressure
see DWR series
31
Accessories Pressure switchesPressure transmittersThermostatsTemperature sensorsFlow monitorsSolenoid valves
Mechanical pressure switches
Additonal functions/Connecting schemes
The prices shown are additional prices compared to the
basic device of the 200 series (plug connection).
* Connection schemes for switching schemes, see page 36.
Please state interval when ordering!
Example for ordering: DCM10-217A-S.
Additional text: switching scheme A4
Example for ordering: How to order:
DCM 6 – 205 Pressure switch
Code of additional function DCM6-205
(e.g. maximum limiter) or DCM6 with ZF205
Code for pressure range
Sensor system
Two micro switches, switching ZF307
in parallel or in succession. Fixed
switching differential, only
possible with terminal
connection housing.
State the switching differential
(not possible with all pressure
switches). (See page 34 + 35).
Two micro switches, 1 plug ZF217 *
switching in succession,
no adjustable switching
differential.
State the switching
scheme * (not possible
with all pressure switches).
(See page 34 – 37). Connection scheme
selection, see page 36
Gold-plated silver contact, ZF213
single pole switching (not
available with adjustable
switching differential).
Switching capacity:
max. 24 VDC, 100 mA,
min. 5 VDC, 2 mA
Switch Housing with ZF351
surface protection
(chemical version)
Plug connection Terminal connection Connection scheme
200 series (IP 54) 300 series (IP 65)
32 Mechanical pressure switches
Additonal functions/Connecting schemes
Pressure switches and pressure monitors
Additional functions for Ex-i-equipment
· Housing (500) with terminal connection (IP 65), "blue" cable entry and terminals.
· Also available with resistor combination for line break and short-circuit monitoring (with isolating amplifier).
Important:
All pressure switches with the ZF5… additional functions listed here can only be operated in combination with
a suitable isolating amplifier.
Additional information:
Our pressure switches and thermostats are considered to be "simple electrical equipment" within the meaning
of standard EN60079-11: 2007. Testing is not mandatory for this type of equipment.
ATEX-Certificate: please see page 10 – 13
!
i
Additional functions for Ex-ia-equipment Connection scheme
Gold-plated contact ZF513
single pole switching, fixed hysteresis,
not adjustable
Switching capacity:
max. 24 VDC, 100 mA, min. 5 VDC, 2 mA
For the power supply circuit:
Ui 24 V DC
Ii 100 mA
Ci 1 nF
Li 100 µH
Versions with resistor combination for line break and short-circuit monitoring in control current circuit, see DBS series,
pages 54 – 56:
For the power supply circuit:
Ui 14 V DC
Ri 1500 Ohm
Ci 1 nF
Li 100 µH
Normally closed contact with resistor ZF574
combination, for minimum pressure
monitoring, gold-plated contact,
plastic-coated housing (chemical version).
Normally closed contact with reclosing ZF575
lockout and resistor combination,
for minimum pressure monitoring,
plastic-coated housing (chemical version).
Normally closed contact with resistor ZF576
combination, for maximum pressure
monitoring, gold-plated contact,
plastic-coated housing (chemical version).
Normally closed contact with reclosing ZF577
lockout and resistor combination,
for maximum pressure monitoring,
plastic-coated housing (chemical version).
see
DBS series
pages 54 – 56
II 1/2G Ex ia IIC T6 Ga/Gb
II 1/2D Ex ia IIIC T80 °C
DWAM6-576
i
33
Accessories Pressure switchesPressure transmittersThermostatsTemperature sensorsFlow monitorsSolenoid valves
Mechanical pressure switches
Service functions
Service functions
Devices with service functions will be produced according to the customer’s specifications.
The system requires that these product combinations are identified in such a way as to prevent any possibility
of confusion. These combinations are characterised by a product code with the suffix "-S" on the packaging
label as well as separate labels with barcodes for each service function.
Service functions are available for the following type series (including Ex versions):
Pressure switches: DCM, DNM, DNS, VNS, VCM, VNM, DDCM, DWR, DWAM, DWAMV, SDBAM, DGM, FD
Ordering devices with service functions
Example:
Ordering 1 DCM6, set at 4 bar rising, identified with code PSH008 as requested by the customer and acceptance test certificate 3.1.
The order confirmation contains:
1 DCM6-S ("S" is need for factory = following lines belong to this item)
1 ZF1970: set to 4 bar rising
1 ZF1978: PSH008
1 AZ3.1B1
Included items: Labels with barcodes on the packaging: Pack contents: 1 DCM6 (without "S" suffix) marked
DCM6-S 1 ZF1970: set to 4 bar rising
ZF1970: set to 4 bar rising 1 ZF1978: PSH008
ZF1978: PSH008 1 AZ3.1 will be sent by extra post
AZ3.1B1 1 Installation and operating instructions
Service functions Plug connection Terminal connection Ex-i/
200 series 300 series Ex-d
Adjustment according to customer’s instruction:
one switching point ZF1970* ZF1970* ZF1970*
two switching points or defined switching differential ZF1972* ZF1972* –
Adjustment and lead sealing according to customer’s instruction:
one switching point ZF1971* – –
two switching points or defined switching differential ZF1973* – –
Labelling of units according to customer‘s ZF1978 ZF1978 ZF1978
instruction with sticker
Special packing for oil and grease-free storage ZF1979 ZF1979 ZF1979
Test reports according to EN 10 204
Certificate 2.2 based on non-specific specimen test WZ2.2 WZ2.2 WZ2.2
Inspection test certificate 3.1 based on specific test AZ3.1B1 AZ3.1B1 AZ3.1B1
Inspection test certificate for FV separating diaphragms AZ3.1-V AZ3.1-V AZ3.1-V
* Switching point adjustment: Please specify switching point and direction of action (rising or falling pressure).
34 Mechanical pressure switches
S2 type series
Switching scheme Switching device Ordering position Additional text
A1 A DCM6-217A-S Switching scheme A1
A2 C DCM6-217C-S Switching scheme A2
A3 C DCM6-217C-S Switching scheme A3
A4 A DCM6-217A-S Switching scheme A4
B1 B DCM6-217B-S Switching scheme B1
B2 D DCM6-217D-S Switching scheme B2
B3 D DCM6-217D-S Switching scheme B3
B4 B DCM6-217B-S Switching scheme B4
C1 B DCM6-217B-S Switching scheme C1
C2 D DCM6-217D-S Switching scheme C2
C3 D DCM6-217D-S Switching scheme C3
C4 B DCM6-217B-S Switching scheme C4
D1 A DCM6-217A-S Switching scheme D1
D2 C DCM6-217C-S Switching scheme D2
D3 C DCM6-217C-S Switching scheme D3
D4 A DCM6-217A-S Switching scheme D4
Note on ordering additional function ZF217
FEMA pressure switches of the DCM (except
DCM1000, DCM4016 and DCM4025), VCM
(except VCM4156), VNM, DNS, VNS series can
be equipped with 2 microswitches.
This is not possible with any other type
series or with Ex versions.
Technical data
Standard equipment
The standard equipment of every two-stage
pressure switch includes a switching device
with 2 microswitches, both single-pole
switching. Switch I monitors the low pressure,
switch II the higher pressure. The setting
ranges indicated in the data sheets for the
basic types apply to the two-stage pressure
switches as well. It should be noted that the
switching differentials of the individual
microswitches may not be exactly the same
due to component tolerances.
Switching difference
The switching interval of the two microswitches
is the difference (in bar or mbar) between the
switching points of the two micro switches.
Example for ZF307:
When the pressure rises (e.g. 2.8 bar), a
two-stage pressure switch turns on a warning
light, and if the pressure continues to rise (e.g.
3.2 bar) the system shuts down. The switching
interval is 3.2-2.8 = 0.4 bar. The following
applies to all versions:
The switching interval remains constant over
the whole setting range of the pressure switch.
If the switching pressure setting is changed
with the setting spindle, the switching interval
does not change - the switching points are
moved in parallel.
Switching differential
The switching differential, i.e. the hysteresis of
the individual micro switches, corresponds to
the values of the relevant basic version referred
to in the Product summary. In the case of
two-stage pressure switches, the switching
differential of the individual micro switches
is not adjustable.
Versions
Two-stage pressure switches are available in
three different versions, each identified by a ZF
number. The versions differ in terms of their
connection schemes and electrical connection
types (terminal or plug connection).
S2 type series
Pressure switches with 2 microswitches - technical data
The applicable data sheet for the basic types contains the technical data for the two-stage pressure
switches. This includes all limits of use, such as temperature, maximum pressure, mounting position,
protection class, electrical data etc. The principal dimensions are the same as for single-stage
pressure switches with comparable pressure ranges and design features.
ZF307 Factory setting
according to
customer’s
instruction
Switching difference
fixed
Terminal
connection
(All terminals
of both
microswitches
are accessible
(6 terminals)
2 x single-pole
switching
1. Basic type with ZF 307
2. Switching points I
and II, with direction
of action in each
case (rising or falling
pressure)
Example: DCM16-307
Switching point I:
10 bar falling
Switching point II:
12 bar falling or
switching interval only.
ZF217 Adjustable
via adjustment
knobs I and II in
accordance with
"Switching
difference" table
Plug connection
in accordance with
DIN EN175301
(3-prong + earth
conductor)
Function-
appropriate
internal wiring in
accordance with
"Switching
functions" table
Example selection
in accordance
with "Switching
schemes" table,
page 36.
1. Basic type with
ZF217
2. Switching scheme
For example:
DCM16-217/B 4
Since all values are
adjustable within the
specified limits, no
further data is required.
Additional Switching difference Electrical Connection Ordering
function between the two connection diagram information required
micro switches
35
Accessories Pressure switchesPressure transmittersThermostatsTemperature sensorsFlow monitorsSolenoid valves
Mechanical pressure switches
S2 type series
S2 type series (selection)
ZF217 pressure switches with two microswitches
and switching difference
Switching difference of two-stage pressure switches (ZF217, ZF307)
Type series
S2
ZF217
ZF307 Higher pressure Lower pressure
min. switching max. switching difference (mean values)
difference
Type Factory Switching scheme Switching scheme Switching scheme
default A1/A3/B2/B4 A2/A4/C2/C4 B1/B3/D1/D3
C1/C3/D2/D4
+ ZF307
DCM06 40 mbar 165 mbar 190 mbar 140 mbar
DCM025 20 mbar 140 mbar 160 mbar 120 mbar
DCM1 40 mbar 240 mbar 280 mbar 200 mbar
DCM3 0.1 bar 0.65 bar 0.75 bar 0.55 bar
DCM6 0.15 bar 0.95 bar 1.2 bar 0.8 bar
DCM10 0.25 bar 1.6 bar 1.85 bar 1.35 bar
DCM16 0.3 bar 2.0 bar 2.3 bar 1.7 bar
DCM25 0.6 bar 4.0 bar 4.6 bar 3.4 bar
DCM40 0.9 bar 6.0 bar 6.9 bar 5.1 bar
DCM63 1.3 bar 8.5 bar 9.8 bar 7.2 bar
DNM025 35 mbar 215 mbar 240 mbar 180 mbar
VCM095 40 mbar 300 mbar 340 mbar 260 mbar
VCM101 40 mbar 260 mbar 300 mbar 220 mbar
VCM301 20 mbar 100 mbar 120 mbar 80 mbar
VNM111 50 mbar 310 mbar 360 mbar 260 mbar
Switching devices with adjustable switching difference
Additional function ZF217
On switching devices with additional function ZF217, the switching differene is continuously
adjustable via two adjustment knobs I and II accessible from outside. The maximum possible
switching difference is stated in the "Switching difference" table.
Turning adjustment knob I clockwise produces a lower switching point for microswitch I
Turning adjustment knob II anticlockwise produces a higher switching point for microswitch II
Adjustment knobs I and II have an internal stop to prevent the micro switches from being adjusted
beyond the effective range.
Adding together the adjustments on knobs I and II results in the switching difference between the two
micro switches. Changes made with the setting spindle do not affect the switching difference. The
switching difference remains constant over the whole setting range of the spindle. The two switching
points are moved up or down in parallel.
Recommended adjustment method for switching devices with ZF217
1. Set adjustment knobs I and II to their basic positions.
Turn adjustment knob I anticlockwise as far as possible.
Turn adjustment knob II clockwise as far as possible.
2. Adjust the setting spindle S by the scale to a value midway between the desired upper and lower
switching points.
3. With pressure applied, set the lower switching point with adjustment knob I.
4. In the same way as in step 3, set the upper switching point with adjustment knob II.
5. If the desired upper and lower switching points cannot be reached, turn the setting spindle S in
the appropriate direction and repeat steps 3 and 4.
36 Mechanical pressure switches
S2 type series
S2 type series
Two-stage pressure switches, switching schemes for ZF217
Function-appropriate internal configuration of microswitches I and II, switching scheme selection table. The switch position shown
corresponds to the pressureless state. On the horizontal axis is the switching function of microswitch I (A–D); on the vertical axis is the
switching function of microswitch II (1–4). At the intersection is the switching scheme which satisfies both conditions (e.g. A 2).
Information required when ordering:
As well as the basic type (e.g. DCM10) and the switching scheme (e.g. A 2), for factory setting it is
also necessary to indicate the switching points and direction of action:
Example: DCM 10-217C-S, switching scheme: A2, Switch I: 6.5 bar falling, Switch II: 7.5 bar rising.
Microswitch I (lower switching point)
falling, close rising, close falling, open rising, open
falling, close
rising, closefalling, open
rising, open
Microswitch II (upper switching point)
37
Accessories Pressure switchesPressure transmittersThermostatsTemperature sensorsFlow monitorsSolenoid valves
Mechanical pressure switches
S2 type series
S2 type series
Examples of use for two-stage pressure switches
Pressure monitoring and controlling can be greatly simplified by using pressure monitors with two
built-in microswitches which can be made to operate one after the other under rising or falling
pressure. For example, minimum and maximum pressure monitoring can be achieved with only
one pressure switch, doing away with the need for a second pressure switch (including the cost of
installation). Step switching, e.g. pressure-dependent control of a two-stage pump, is of course also
possible using this special series.
Example 1:
Requirement
Pressure holding devices and automatic expansion valves usually have a gas cushion whose pressure
must be kept constant within a certain range. If the pressure is too low, a compressor is switched on.
If the pressure is too high, a solenoid valve must be opened to vent the gas. Between these two
levels is a neutral zone, in which the compressor and the solenoid valve are at rest.
Solution
All pressure switches of types DCM, DNS, each with additional function ZF217 and switching scheme
A 2, are suitable. All pressure ranges listed in the technical documents are possible. Example for
ordering: see page 24
Switching function / connection scheme
Switch I: With falling pressure, contact 1–2 closes (compressor on)
With rising pressure, contact 1–2 opens (compressor off)
Switch II: With rising pressure, contact 2–3 closes (valve open)
With falling pressure, contact 2–3 opens (valve closed).
In between there is a neutral zone in which the compressor is not switched on
and the solenoid coil is not energized (off position).
Example 2:
Requirement
In a process engineering system, the pressure in a nitrogen line has to be monitored. A green signal
lamp indicates that the pressure in the line is between 2.2 and 2.6 bar. If the pressure goes below 2.2
bar or above 2.6 bar, the indicator lamp goes out and the system shuts down.
Solution
The first contact of a DCM3–307 pressure switch with 2 microswitches opens under falling pressure
at 2.2 bar; the second microswitch opens under rising pressure at 2.6 bar. If the pressure is >2.2 bar
or <2.6 bar, the circuit is closed via both microswitches and the signal lamp is lit.
Minimum and maximum pressu-
re monitoring in a nitrogen line
For pressure-dependent control
of automatic expansion valves
and pressure holding devices
Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
Honeywell:
DCM1-303 DCM1-301 DCM06-213 DCM1000-351 DCM4025-313 DCM6-351 DCM6-355 DCM3-205 DCM16-351
DCM16-353 DCM506-301 DCM1000-301 DCM6-353 DNM025-213 DCM3-206 DCM1-353 DCM6-305 DCM63-
213 DCM40-205 DCM6-301 DCM6-303 DCM16-363 DCM6-306 DCM1-351 DNM025 DNM025-301 DCM1-205
DCM6-513 DCMV6-213 DCM625-353 DCM025 DCM025-353 DCM63-313 DCM16-213 DNM025-513 DCM40-513
DCM625-351 DCM025-351 DCM10-313 DCM1-206 DCM4025 DCM16-513 DCMV625 DCM4025-213 DCM06
DCM40-301 DCM025-363 DCM4016-513 DCM6-205 DNM025-351 DCM10-206 DCM40-305 DCM10-205
DNM025-205 DCM6-206 DCM40-306 DCMV63 DCM16-303 DCM4016-351 DCM1000-363 DCM16-301 DCM16-
305 DCM4016-206 DCM10-363 DCM40-351 DCM10-213 DCM25-303 DCM625-205 DCM25-301 DCM506
DCM3-306 DNM025-313 DCM1-363 DCMV16-213 DCM625 DCM1000-563 DCM63-301 DCM625-206 DCM025-
563 DCM025-206 DCM025-205 DCM4016 DCM3-303 DCMV10 DCMV16 DCM3-301 DCM63-353 DCM10-563
DCM3-305 DCM1-213 DCM06-301 DCM025-313 DCM10 DCM6-213 DCM16 DCM25-213 DCMV025 DCM3-351
DCM06-513 DCM3-353
