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DG 023 · DG 024 · DG 041 · DG 042
for Pressure and High Pressure Filters · Operating pressure up to 450 bar · Response/switching pressure up to 5,0 bar
Clogging Indicators
Application
Monitoring the contamination of pressure and high pressure
filters.
General
Filter elements installed in hydraulic filters remove dirt from a
hydraulic system and therefore become contaminated themsel-
ves. Free pores or spaces in the filter material are obstructed by
dirt parti cles, which causes a continuous increase in the pressure
loss.
The dirt load collected in a filter element gradually increases
during service, which also leads to a higher pressure drop. The
resulting differential pressure ∆p is monitored by a clogging
indicator. Once a preset value is reached, an electrical and/or
optical signal is generated.
The following must be observed in this context:
The pressure drop caused by the filter element increases
depending on the flow rate, the dirt load, and the viscosity of
the pressure fluid.
Therefore, a filter element is not regarded contaminated before
the clogging indicator responds at operating temperature of the
hydraulic system, causing a continuous signal.
Consequences of an overdue filter element change
For filters equipped with a bypass valve:
The more dirt has collected in the filter element, the more
frequently the bypass valve opens and part of the hydraulic fluid
remains unfiltered. The high pressure loss causes unnecessary
power consumption.
For filters without a bypass valve:
The increasing pressure loss across the filter element, which
reduces the efficiency of the hydraulic system, eventually causes
malfunctions to occur or a pressure relief valve to respond.
Description
100
70
60
50
0
50
10095
Response range of clogging indicator
Typical development of dirt accumulation in a
filter element during its service life
Service life [%]
Differential pressure[%]
Clogging Indicators
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Special design features
Piston seal:
The piston actuated by the differential pressure is equipped with
a leak-free O-ring seal. As a result, the total flow passes the filter
element.
Proximity position sensing:
Piston movement is detected by sensing a magnetic field, i.e.
without mechanical contact. For this reason, ARGO-HYTOS
clogging indicators are absolutely leakfree.
Characteristics
Operating pressure
0 ... 315 bar, min. 10
7
pressure cycles
Nominal pressure according to DIN 24550
0 ... 450 bar, min. 10
4
pressure cycles
Quasi-static operating pressure
Connection
For the flange hole layout please refer to the section Dimensions
(other fittings on request).
Hydraulic fluids
Mineral oil and biodegradable fluids
(HEES and HETG, see info-sheet 00.20)
Temperature range of fluids
-30 °C ... +100 °C (short term 125 °C)
Ambient temperature range
-30 °C ... +80 °C
Materials
Housing: Aluminium alloy
Piston: Brass
Socket: Polyamide
Display piece DG 042: Polyamide
Seals: NBR (FPM on request)
Operating voltage
10 ... 30 V DC
(only required for clogging indicators with built-in LEDs)
Electrical service life
Min. 10
7
switching cycles
Electrical protection
IP 65 (with mounted and secured socket)
Mounting position
No limitation
Design and principle of operation
Within the clogging indicator, the differential pressure
∆p = p
1
- p
2
(pressure upstream of the element minus pressure
downstream of the element) caused by the filter element acts on
a magnetic piston against the force of a spring.
In optical (mechanical) clogging indicators, the increasing
differential pressure causes the piston to approach a second
magnet with reversed polarity which in turn causes the indicator
to change from green to red.
In electrical clogging indicators, the magnetic piston triggers a
reed switch.
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Overview of types
DG 042 - Optical differential pressure indicator Function:
When the preset differential pressure is reached, the optical
indicator changes from green to red. If the pressure differential
returns to a value below the preset limit, the indicator changes
back to green, i.e. no manual reset of the indicator is required.
DG 041-Electrical differential pressure switch
(change-over)
Function:
When the preset differential pressure is reached, the built-in
Reed switch changes over.
The change-over (CO) switch makes it possible to indicate a
broken wire by means of a suitable electronic circuit, as com-
pared to a make contact (normally open NO) switch.
Option:
The transparent socket with 2 built-in LEDs makes it possible to
have an additional optical indication of the filter contamination.
When the operating voltage is switched on, a green LED lights
up. When the switching pressure is reached, a yellow LED lights
up in addition.
DG 023 - Electrical differential pressure switch with
temperature suppression (change-over)
Function:
The built-in Reed switch changes over when the preset differen-
tial pressure is exceeded.
If the temperature drops below 32 °C, a temperature switch
opens and suppresses the signal of the differential pressure
switch.
The transparent socket with 2 built-in LEDs makes it possible to
have an additional optical indication of the filter contamination
(function described at DG 041).
DG 024 - Electrical differential pressure switch with
2 switching points (break)
Function:
When 70 % of the preset differential pressure is reached, the
first Reed switch opens, at 100 % the second built-in Reed
switch opens.
Note:
Since the differential pressure of a filter element rises at an
exponential rate towards the end of the element’s service life
(refer to the Description section), approximately 95 % of the
service life has expired when the first Reed contact opens
(at 70 % of ∆p setting).
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Selection Chart
Remarks:
› The response/switching pressure of the clogging indicator must be lower than the cracking pressure of the bypass valve of the
filter.
› The clogging indicators listed in this chart are standard units. Other designs available on request.
› Mounting accessories are not included in the scope of delivery and must be ordered separately (Part-no. see spare parts).
› Reed switches are sensitive of excessively strong currents. Even a short-term overload causes an increased contact resistance or
failure of the switch. By taking the following precautions, premature failure of Reed switches due to overload is avoided.
Wiring suggestions:
Current limiter for DC and AC voltage:
If light bulbs or other loads are connected over long distances (conductor capacity!),
a protective resistor should be connected in series in order to limit the current.
The same applies when capacitance loads are connected.
Spark suppression in DC applications:
The contacts of Reed switches open extremely fast, causing voltage peaks to be induced
when switching off inductive loads, such as relays, lifting magnets, or solenoid valves.
The resulting self-induction currents are short-circuited by connecting a diode in parellel
to the inductive load.
Spark suppression in AC applications:
In AC applications, a diode connected in parallel to the load is not sufficient.
RC elements should be used here, connected in parallel to the Reed switch.
Please contact our design engineers for advice in order to select a suitable RC element.
U
C R
load
U
load
U
C
R
load
Part no.
Optical indicator
Electrical switch
Temperature suppression
< +32 °C S
1
Response/switching
pressure S
2
/ S
3
Type of contact
Switching voltage U
Switching current I
Switching power P
Symbol
Weight
Remarks
bar V AC/DC A AC/DC VA/W AC/DC kg
1 2 3 4 5 6 7 8 9 10 11 12
DG 042-01 • - - 2,0 - - - - 1 0,17 -
DG 042-02 • - - 5,0 - - - - 1 0,17 -
DG 041-61 - • - 1,2 change-over 120/175 0,17/0,25 3,5/5,0 2 0,19 with socket
DG 041-31 - • - 2,0 change-over 120/175 0,17/0,25 3,5/5,0 2 0,19 with socket
DG 041-44 • • - 2,0 change-over - /30 - /0,25 - /3,0 3 0,19 with socket
DG 041-32 - • - 2,5 change-over 120/175 0,17/0,25 3,5/5,0 2 0,19 with socket
DG 041-33 - • - 5,0 change-over 120/175 0,17/0,25 3,5/5,0 2 0,19 with socket
DG 041-43 • • - 5,0 change-over - /30 - /0,25 - /3,0 3 0,19 with socket
DG 023-03 • • • 2,0 change-over - /30 - /0,25 - /3,0 4 0,34 with socket
DG 023-02 • • • 5,0 change-over - /30 - /0,25 - /3,0 4 0,34 with socket
DG 024-02 - • - 3,5/5,0 break 120/175 0,17/0,25 3,5/5,0 5 0,27 with socket
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Dimensions
B
A
ØC
H
F
E
E
ØL
ØK
Q
M
P
2
P
1
E
OP
N
H
E
F
G
A
C
C
B
B
A
E
F
H
S
ØR
P
DG
0
4
2
Mounting holes
DG
0
41
Minimum distance
from ferromagnetic
parts: 7 mm
Flange hole layout
D
G
023
/
D
G
024
Holes p
1
/ p
2
p
1
= Higher static pressure
p
2
= Lower static pressure
Measurements
Type A B C E F G H I K L M N O P Q R S T U
DG 042 30 30 21,5 8 67 - 93 6 4,5 8 20 39 3 34 44 7,2 1,1 M4 6
DG 041 30 30 17,5 11 70 83 115 6 4,5 8 20 39 3 34 47 7,2 1,1 M4 6
DG 023 30 50 - 12 76 88 121 6 4,5 8 20 39 3 34 48 7,2 1,1 M4 6
DG 024 30 35 - 9 77 89 122 11 4,5 8 20 39 3 34 45 7,2 1,1 M4 6
Symbols
1 2 3 4 5
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Spare Parts
2
2
1a
1b
2
3
4
5
6
1
DG 042
DG 041 / DG 024
DG 041 / DG 023
Pos. Designation Part No.
1 Mounting accessories * for versions
without temperature compensation
DG 020.1710
1 Mounting accessories * for versions
with temperature compensation
DG 020.1730
1a Bolt* M4 x 30
DIN 912-8.8
11272600
1a Bolt* M4 x 50
DIN 912-8.8
18077800
1b Spring washer* B4 DIN 127 11272700
2 O-ring 4,5 x 1,5 N007.0041
3 O-ring 12,3 x 2,4 N007.0124
4 Display piece assy (with pos. 3) DG 042.1410
5 Socket
DIN 43650 - AF3
DG 041.1220
6 Socket with 2 LED
DIN 43650 - AF3
DG 041.1200
The functions of the complete filters as well as the outstanding
features of the filter elements assured by ARGO-HYTOS can only
be guaranteed if original ARGO-HYTOS spare parts are used.
*Not included in basic unit
Quality Assurance
Quality management according to DIN EN ISO 9001
Various quality controls during the production process guarantee the leakfree function and solidity of our products.
Illustrations may sometimes differ from the original. ARGO-HYTOS is not responsible for any unintentional mistake in this specification sheet.
