Flame-proof / dust-ignition-proof

Seismic monitoring system (SW-52EX / SW-52ST)

Uses high resolution servo accelerometer which can detect microearthquakes
SW-52EX / SW-52ST can provide alarm outputs for control in the event of an earthquake on gas and dust explosion areas such as petrochemical or hydrogen plants, manufacturing plants, etc. High resolution servo accelerometer enables to prevent secondary disasters caused by earthquakes.
Flame-proof / dust-ignition-proof Seismic monitoring system (SW-52EX / SW-52ST)


  • ■ Reliable accuracy
    Reliable accuracyBuilt - in servo type accelerometer is also used for detection of micro-tremor. Both indication setting and alarm setting is 1 gal step.
  • ■ Waterproof structure
    Waterproof structureIt is ideal to install the seismometer on the common foundation to catch the motion of earthquake correctly. SW-52EX / 52ST adopts IP67 waterproof structure which is able to be installed outside or dusty environments.
  • ■ Available to large-scale earthquake monitoring
    The peak of motion in any direction can be surely captured by vector composition of the accelerations detected by the accelerometers arranged in three directions. The measurable acceleration range up to 5000 gal prepare against the large-scale earthquake.
    Available to large-scale earthquake monitoring
  • ■ Flame-proof structure
    * Only SW-52EX
    The container is constructed to withstand the pressure when explosive gas explosion occurs and not to catch fire.
  • ■ Standard communication method
    RS-485(ModBus)is adopted.

System composition

System composition

Flame-proof / dust-ignition-proof specification

Certification Ex db IIB+H2 T6 Gb (IECEx, ATEX),
Ex d IIB+H2 T6 Gb (TIIS)
Ex tb IIIC T120℃ Db (IECEx, ATEX,TIIS)
IECEx DEK 16.0004X
IECEx IEC 60079-0:2011
IEC 60079-1:2014-06
IEC 60079-31:2013
ATEX EN 60079-0:2012+A11
EN 60079-1:2014
EN 60079-31:2014
TIIS Explosion-protected electrical installations in general industries

Classification of explosive gas

450°C≧ T1 >300°C 300°C≧ T2 >200°C 200°C≧ T3 >135°C 135°C≧ T4 >100°C 100°C≧ T5 >85°C85°C ≧ T6
ⅡA NH3, CO, C2H6,
C7H8, C3H8, CH4
C2H6O, C4H10O,
C4H10, C5H8O2,
C6H14, gasoline,
Kerosene, C5H12
C2H4O, C3H9N Ethyl nitrite
Coal gas
Ethyl acrylate,
C2H6O, C6H12,
ⅡC H2 C2H2 CS2 C2H5NO3

Main explosive gas targeted by this product

Classification of explosive dust (GroupⅢ)

Type of dust Electric resistance Representative materials
ⅢA Combustible flyers
Size > 500 μm
Textiles such as rayon, cotton, sisal hemp, jute
ⅢB Non-conductive dust
Size ≦ 500 μm
Electric resistance > 103Ωm Powder such as cereal flour, sugar, toner, synthetic resin powder
ⅢC Conductive dust
Size ≦ 500 μm
Electric resistance ≦ 103Ωm Metal powders such as carbon black, aluminum, magnesium

Outward dimensions



Item Specification
Detection method All-directional detection based on vector composition acceleration
Built-in pickup Force-balancing servo acceleration pickup
Frequency range 0.3 to 10 Hz ±10 %
Maximum range 0 to 5000 Gal (composite value of 3-component vector)
NS and EW axes : ±3000 Gal / UD axes : +2000 to -3000 Gal
Frequency range 0.3 to 10 Hz ±10 %
SI value
Maximum range 0 to 5000 Gal (composite value of 3-component vector) Cycle : 2 seconds, 5000 Gal, Damping : 2%)
Cycle range 0.1 to 2.5 seconds
Real-time calculation of speed response spectrum at measuring acceleration through twenty-five simulation filters with 1-degree of freedom, Inherent cycle : 0.1 sec. step
Damping 2 to 30 % (Arbitrary setting in 1 % step)
Low pass filter 30 Hz (-3 dB), 4th butterworth
A / D converter 24 bit, 100 Hz sampling
Seismic intensity scale calculation method Modified Mercalli intensity scale (PGA estimated value)
Analog output 4 to 20 mA DC x 2 pcs (Load resistance : 300 Ω or less) Selection of “Acceleration”, “SI” or “MMI scale” for each output
MMI scale : Full-scale is fixed, 10-level output in 1.6 mA step
Relay output 1a contact (Photo-MOS relay)
Contact rating : 40 V, 0.8 A (For AC and DC, peak value)
Output content : “Seismic alarm” or “FAULT alarm” can be selected
Digital output Open-collector output × 3 pcs. (D-GND is common)
Output rating : 30 V, 50 mA
Output content : “Seismic alarm” or “FAULT alarm” can be selected.
Alarm Seismic alarm Alarm is output when the system detects earthquake and the measured value exceeds a preset level. Upper limits of 4 levels (Digital output 1 to 3, Relay output) can be individually specified.
Output factor : “Acceleration” or “SI value” can be selected Output level : 0.1 to 999.9 (Gal / Kine)
0.1 step, 0.0: Alarm is OFF Reset time: 1 to 9999 seconds, 1-sec. step 0 sec. : Auto-reset is disabled
FAULT alarm The alarm is output at detection of any of the following errors “Hardware self-diagnosis”, “Pickup self-diagnosis”, “Pickup test” or “System power failure”
Seismic alarm reset Internal timer or digital input (Digital input setting is required)
Digital input Open-collector or non-voltage contact input x 1 pcs. (D-GND is common.)
Open voltage : Approx. 13 V (ViH: 2.4 V or more, ViL: 0.8 V or less)
Input pulse width : 0.1 sec. or more
Function can be changed depending on communication setting:
[Seismic alarm reset / Time correction / Pickup test execution]
Serial I/F Communication with host : Measurement data collection, system setting change, status monitoring, pickup test execution, digital input function changeover
Interface : RS-485 (2-wire type half-duplex communication)
Communication speed : 115,200 bps
Protocol : Modbus (RTU mode)
Clock Accuracy 20 ppm (monthly error: 50 seconds) or less
Calibration ±30 sec. correction using digital input (Digital input setting is required)
Operational temperature range 0 to + 50 ℃
Operating humidity range 10 to 100 %RH (non-condensing)
Power supply DC 24V ±10 % 10 W or less
Structure Aluminum
Installation method Installation on the ground (fixed by anchor)
Construction SW-52EX Ex db IIB+H2 T6 Gb (IECEx, ATEX),
Ex d IIB+H2 T6 Gb (TIIS)
Ex tb IIIC T120℃ Db (IECEx, ATEX,TIIS)
SW-52ST IP67 (Dustproof, watertight structure)
Mass Approx. 5 kg Approx. 2 kg
I/O cable Cable ground (Internal terminal block connection) Connection with waterproof connector