Datasheet Content
DWR
Pressure monitors
Especially suitable as a pressure monitor This pressure switch is "of special construction"
or pressure limiter for fuel gases (DVGW and has been tested with 2 million operating
Worksheet G 260) and liquid fuels (e.g. fuel oil), cycles. TÜV and DVGW tests exists.
as well as for steam systems according to TRD
604 and hot-water systems to DIN EN12828,
systems in accordance to DIN EN12952-11
and DIN EN12953-9. The DWR is used to
monitor maximum and minimum pressures.
SIL 2 according IEC 61508-2
DWR625
Technical data Component tested for Steam Systems according to TRD 604
Hot water Systems according to DIN EN12828
Pressure connection
External thread G 1/2 (pressure gauge Fuel gases DVGW Worksheet G 260
connection) to DIN 16 288 and internal thread Pressure tank DIN EN764-7
G 1/4 to ISO 228 Part 1 (for gas applications
internal thread permissible only up to 4 bar).
Function Pressure monitor or pressure limiter
(with external interlock)
Switching device
Rugged housing (200) made of seawater-
Direction of action For maximum and minimum pressure monitoring
resistant diecast aluminium. (DWFS, SDBFS)
Materials
Sensor "of special construction" by testing with 2 million cycles.
Pressure bellows: Material no. 1.4571
Sensor housing: Material no. 1.4104 Switch
housing: GD AI Si 12 (DIN 1725)
Mounting position Product Summary
Vertically upright and horizontal.
Ambient temperature at switching device Type Setting range Switching Maximum Dimen-
–25 to +70°C,
Medium temperature –25 to +70°C. The differential working sioned
maximum medium temperature at the pressure (mean values) pressure drawing
sensor must not exceed the permitted ambient
temperature at the switching device.
Temperatures may reach 85°C for short periods. Pressure monitors without differential adjustment p. 21 + 22
Higher medium temperatures are possible DWR06 0.1…0.6 bar 0.04 bar 6 bar 1 + 15
provided the above limit values for the switching
device are ensured by suitable measures
DWR1 0.2…1.6 bar 0.06 bar
(e.g. siphon). DWR3 0.2…2.5 bar 0.1 bar 16 bar 1 + 18
Mounting
DWR6 0.5…6 bar 0.2 bar
Directly on the pressure line (pressure gauge DWR625 0.5…6 bar 0.25 bar 25 bar 1 + 17
connection) or on a flat surface with two 4 mm DWR16 3…16 bar 0.5 bar
Ø screws.
DWR25 4…25 bar 1.0 bar 63 bar 1 + 16
Calibration DWR40 8…40 bar 1.3 bar
The DWR series is calibrated for rising pressure.
This means that the adjustable switching pressure
on the scale corresponds to the switching point at Switching differential adjustable
rising pressure. The reset point is lower by the DWR06–203 0.1…0.6 bar 0.08…0.5 bar 6 bar 1 + 15
amount of the switching differential. (See also
page 17, 2. Calibration at upper switching point). DWR1–203 0.2…1.6 bar 0.15…0.6 bar
In version ...-203 the switching differential is DWR3–203 0.2…2.5 bar 0.17…1.2 bar 16 bar 1 + 18
adjustable. The basic calibration is maintained.
DWR6–203 0.5…6 bar 0.3…1.4 bar
Bursting pressure DWR625–203 0.5…6 bar 0.4…2.5 bar 25 bar 1 + 17
For all types ≥ 100 bar, verified by TÜV test.
DWR16–203 3…16 bar 0.75…3.15 bar
Switching differential For values see Product DWR25–203 4…25 bar 1.3…6.0 bar 63 bar 1 + 16
Summary.
DWR40–203 8…40 bar 2.3…6.6 bar
Contact arrangement Single pole changeover
switch.
Switching 250 VAC 250 VDC 24 VDC
capacity (ohm) (ind) (ohm) (ohm)
Normal 8A 5A 0.3 A 8A
Degree of protection IP 54 according to
DIN 40 050
50 Mechanical pressure switches
Tested to PE Directive 97/23/EC
DBS
Pressure monitors / pressure limiters
In many aspects, safety-engineered pressure monitoring lines for short-circuit and line
limiters offer a higher degree of safety compared break and therefore offers an additional safety
with normal pressure switches and are therefore advantage – even in non-Ex-zones. For
especially suitable for chemical process Ex-applications, the isolating amplifier must be
engineering and thermal installations in which installed outside the Ex-zone. The lines between
safety is an especially critical factor in pressure the isolating amplifier and the pressure switch
monitoring. Pressure switches can also be used are monitored for short-circuit and line break.
in Ex- zones (zone 0, 1, 2 and 20, 21, 22) and,
in all cases, require an isolating amplifier. SIL 2 according IEC 61508-2
DWAM6-576
The isolating amplifier is also responsible for
Technical data Safety requirements for pressure limiters
Pressure limiters "of special construction" (DBS) must fulfil additional safety requirements, i.e. breakage
Greater safety
· in process engineering and chemical or leakage in the mechanical part of the sensor must lead to shutdown to the safe side. The pressure
installations, limitermust respond as if the system pressure had already exceeded the maximum limit. The control
· in gas and liquid gas installations
circuit for the pressure limiter must also be considered from the point of view of safety, as short-circuits
Basic features: in the supply lines or other faults in the control current circuit can lead to dangerous conditions.
– "Of special construction" according to VdTÜV
Memorandum "Pressure 100"
– Line break and short-circuit monitoring- Switching element with positive opening operation and gold-plated contacts
between pressure switch and isolating The microswitch is equipped with positive opening operation. Rather than transmitting the plunger force
amplifier via a spring, which is the usual method with most microswitches, this newly developed microswitch has
– Suitable for Ex areas (zone 0, 1 & 2 or 20, 21
& 22) (explosion protection Ex-ia) an additional lever which transmits the movements of the pressure bellows positively to the contact lever.
– Degree of protection IP 65 If the spring breaks, the contact lever is moved directly.
– Plastic-coated housing (chemical version)
Options: Line break and short-circuit monitoring in the control circuit
– Limiter with internal interlock The resistor connected in series with the switching contact limits the current to a defined value with the
Type-specific features: switch closed. In the event of short-circuit in the area between the isolating amplifier and the series
– Self-monitoring sensors resistor, the current rises above the predetermined limit value, the relay of the isolating amplifier drops
– Positive opening microswitches out, the output current circuit is interrupted and thus the safe condition is achieved. In the event of a line
– Gold-plated contacts
– TÜV, DVGW component tests break, the current flow is interrupted, the relay drops to the safe side and interrupts the output current
circuit (safety sequence). Furthermore, the isolating amplifier is designed so that, if faults occur in the
electronics (conductor interruption, component defect etc.) and in the resulting situations, the safe
shutdown condition is assured. These characteristics of the safety-engineered isolating amplifier,
including line break and short-circuit monitoring, satisfy the requirements of DIN/VDE 0660, Part 209.
Connection diagram
For pressure monitoring in Ex areas, the isolating amplifier must be installed outside the Ex-zone.
The pressure limiter has an intrinsically safe control current circuit (Ex-ia). This arrangement is suitable
for zones 0, 1 and 2, 20, 21 and 22.
M e c h a n i c a l p r e s s u r e s w i t c h e s 51
Tested to PE Directive 97/23/EC
Pressure switches…
