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Brand: RKI
RKI T3A Three-Wire Explosion-Proof Gas Transmitter
Description
A three-wire explosion-proof gas transmitter with graphical display
The RKI T3A is a wire-powered (12 to 35 VDC) gas transmitter that takes an electrochemical, infrared or catalytic-bead sensor and shows readings on a sunlight-readable graphical LCD with LED backlight. It outputs 4-20 mA (3-wire) and RS-485 Modbus as standard, has two individually configurable alarms with amber and red front LEDs, and can carry two optional programmable dry-contact relays. Three push buttons and three magnetic switches allow non-intrusive calibration through the housing, and the unit works with all RKI Beacon controllers and most DCS or PLC systems.
Technical specifications
| Parameter | Specification |
|---|---|
| Sensor types | Electrochemical, infrared, catalytic bead |
| Operating voltage | Wired power (3-wire), 12 to 35 VDC; 2 W maximum |
| Outputs | 4-20 mA analog (3-wire) and RS-485 Modbus; fault terminal wet relay contact; optional 2 dry-contact relays with replaceable 4 A fuses |
| Display and interface | 102 x 64 graphical LCD, transflective, white LED backlight; 3 push buttons (MENU, ADD, SUB) and 3 magnetic switches |
| Protection | Power EMI filter; 4-20 mA and RS-485 surge suppression |
| Temperature range | -40 to +54 C (-40 to +129 F) |
| Dimensions and weight | 5.5 in L x 6 in W x 7 in H (maximum with attachments 8 in W x 17 in H); 6 lb |
| Remote sensor kit (optional) | Electrochemical 250 ft, infrared 40 ft, catalytic bead 15 ft maximum cable; kit part 61-2001 |
| Hazardous location | Certified explosion / flame proof CQPSUS, Class I, Division 1 and 2, Groups B, C and D; enclosure NEMA 3, 4, 4X, 7 (B, C, D), 9 (E, F, G), -20 to +60 C; sensor housing -40 to +60 C |
| Controllers | Beacon 110, 200, 410A, 800 and MC-6400, plus most DCS / PLC systems |
| Warranty | One year, electronics and sensor |
RKI notes that certification applies only to some gases: toxic gases not certified for Division 1 are suitable for Division 2 applications but have no third-party approval.
Gas types, ranges and classification
| Gas | Range | T90 | Hazard classification (datasheet) |
|---|---|---|---|
| LEL catalytic | 0-100% LEL (0-5% vol) | < 90 s | Class I, Div 1 |
| LEL-IR | 0-100% LEL (0-5% vol) | < 30 s | Class I, Div 1 |
| LEL-IR-HC | 0-100% LEL | < 30 s | Class I, Div 1 |
| CO | 0-300 ppm | < 30 s | Class I, Div 1 |
| CO2 | 0-5% vol | < 30 s | Class I, Div 1 |
| H2S | 0-100 ppm | < 30 s | Class I, Div 1 |
| H2S 2K | 0-2000 ppm | < 25 s | Class I, Div 1 |
| O2 | 0-25% vol | < 15 s | Class I, Div 1 |
| SO2 | 0-20 ppm | < 35 s | Class I, Div 1 |
| Cl2 | 0-10 ppm | < 60 s | Class I, Div 2 |
| ClO2 | 0-1 ppm | < 120 s | Class I, Div 2 |
| ETO | 0-10 ppm | < 120 s | Class I, Div 2 |
| HCl | 0-30 ppm | < 300 s | Class I, Div 2 |
| HCN | 0-30 ppm | < 70 s | Class I, Div 2 |
| HF | 0-10 ppm | < 90 s | Class I, Div 2 |
| NH3 / NH3 300 / NH3 A | 0-100 / 0-300 / 0-1000 ppm | < 90 / 120 / 120 s | Class I, Div 2 |
| NO2 | 0-20 ppm | < 25 s | Class I, Div 2 |
| O3 | 0-5.0 / 100 ppm | < 30 s | Class I, Div 2 |
| PH3 | 0-5 ppm | < 30 s | Class I, Div 2 |
Installation and selection notes
The T3A manual (part 71-0533) covers wiring to the three-wire terminal block, where the power terminal takes wire down to 26 AWG and relay terminals up to 14 AWG. For sensors that must sit away from the amplifier, such as hot ducts or hard-to-reach points, the remote sensor kit uses a second junction box on a cable ordered in one-foot increments within the maximum lengths above; the cable and gland supplied are not explosion-proof and must be replaced with an explosion-proof gland if installed in a classified location. Choose infrared where catalytic poisons such as silicones are present, and confirm the approval class for the gas you need, since Division 1 and Division 2 gases are listed separately.
Documents and quotation
The attached file is the two-page RKI T3A datasheet. For the controller side see the
and fire and gas detectors. Send gas, range, area classification, controller and cable run for a quotation.
Datasheets & Documents
- Datasheet RKI T3A 3-wire explosion proof transmitter datasheet (2 pp) Download
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About brand
RKI Instruments, Inc. designs and manufactures gas detection equipment for industrial, commercial and environmental safety. The company was founded in 1994, is headquartered in Union City, California, and works with Riken Keiki of Japan on gas detection and sensor technology. Seven Star LLC is an independent supplier in Muscat and lists its portable gas monitors.
RKI gas detection range
The range covers portable monitors such as the GX-3R Pro, GX-Force and GX-6100, fixed-system detectors and controllers, wireless gas detection and calibration equipment. Typical uses are confined-space entry, refinery and petrochemical work, water and wastewater, and leak detection, with intrinsically safe approvals on the portable models.
Ordering RKI monitors
Tell us the gases and ranges, whether diffusion or sample-draw is needed, battery type and the approval marking required on site. We check the sensor configuration and calibration gas against the manufacturer datasheet before quoting. Pump-sampling units suit pre-entry checks of tanks and manholes, while compact diffusion monitors suit personal protection.
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Frequently Asked Questions
What power supply does the T3A need?
Wired three-wire power from 12 to 35 VDC, with a 2 W maximum draw.
What outputs are standard?
4-20 mA (3-wire) analog and RS-485 Modbus; two dry-contact alarm relays are optional.
How far can the sensor be remote-mounted?
With the optional kit: 250 ft for electrochemical, 40 ft for infrared and 15 ft for catalytic bead sensors.
What hazardous-area marking does it carry?
The datasheet lists certified explosion / flame proof CQPSUS, Class I, Division 1 and 2, Groups B, C and D, for the enclosure and sensor housing; some toxic gases are Division 2 only.
Which controllers work with it?
Beacon 110, 200, 410A, 800 and MC-6400, and most DCS or PLC systems.
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