Oldham OLCT 710 Fixed Gas Detector
Overview
The Oldham OLCT 710 is an intelligent fixed gas detector from Teledyne Oldham Simtronics, part of the OLCT 700/710 series designed for harsh and extreme industrial locations. It consists of an OLCT 700 smart sensor module attached to a flameproof junction box with terminal blocks and an optional surge protection board, and the complete assembly is flameproof (Ex d) certified with ATEX approval. Depending on the plug-in sensor, the detector monitors combustible hydrocarbons, carbon dioxide or hydrogen sulfide, and it is SIL2 certified according to IEC 61508 (except the CO2 version).
Seven Star LLC supplies the Oldham OLCT 710 to oil and gas producers, gas processing plants, refineries, terminals, water and wastewater utilities and power stations in Oman and across the GCC. We provide engineering support in Muscat to help customers choose the sensor technology, range and accessories for their hazardous areas in Sohar, Duqm, Salalah and the interior fields.
Measurement Principle
Three sensor technologies are available for the Oldham OLCT 710. The IR version uses a non-dispersive infrared (NDIR) cell with an infrared lamp, an optical chamber and two pyroelectric detectors: an active detector filtered to the absorption band of the target gas and a reference detector filtered to a non-absorbing band. The ratio of the two signals gives the gas concentration and cancels drift from lamp ageing or changes in reflectivity. IR sensors are immune to poisoning by corrosive gases, work without oxygen and have an expected service life of five years or more, but they respond only to hydrocarbon gases, not to hydrogen, ammonia, CO or H2S.
The FP version of the Oldham OLCT 710 uses a matched pair catalytic bead sensor for non-selective combustible gas detection from 0 to 100% LEL. The TP version detects hydrogen sulfide with a CHEMFET MOS solid-state sensor suitable for wide temperature and humidity ranges, with ranges of 0 to 20, 50, 100 or 200 ppm and a five-year sensor warranty. A CO2 infrared version measures 0 to 5% vol as standard. Sensors are plug-in components with gold-plated connections and can be changed in the field by releasing a locking screw and unthreading the housing bottom.
Engineering Design of the Oldham OLCT 710
All metal parts of the Oldham OLCT 710 sensor module are electropolished 316 stainless steel, and the microprocessor electronics are fully encapsulated, which removes failures from water ingress, corrosion and vibration. Multi-layer transient spike protection protects the circuitry, and the junction box can carry an optional surge protection termination module. A scrolling alphanumeric LED display behind a corrosion-resistant lens shows the reading, status and scripted messages, and an integral calibration port and splashguard are fitted at the sensor end.
The operator interface of the Oldham OLCT 710 is non-intrusive: a small handheld magnet activates two programming switches through the housing, so calibration and configuration are done without opening the enclosure. An auto zero and auto span sequence guides the technician step by step. The detector runs on 11.5 to 28 VDC with typical consumption below 2 W and provides both a linear 4-20 mA analog output and a Modbus RTU RS-485 serial output. Pre-emptive diagnostics monitor input voltage, operating temperature, detector signal amplitude, output loop integrity and remaining sensor life and report them through both outputs.
Installation and Maintenance
According to the Teledyne Oldham Simtronics user manual, the Oldham OLCT 710 must only be installed in areas whose classification matches its ATEX label. Cable glands must be flameproof (Ex d) certified, of M20 × 1.5 thread with at least five threads engaged, and must keep the ingress protection at IP66 or better. Cables should be rated for an operating temperature of 80 °C or more, and only non-hardening, non-corrosive lubricants without volatile solvents may be used on the threaded joints.
Infrared units leave the factory calibrated for methane; for any other hydrocarbon the detector must be span calibrated and configured for that gas. Compared with catalytic sensors, the IR sensor shows better long-term zero and span stability: typical zero checks are quarterly to semi-annual and span checks semi-annual to annual, although field experience should set the final interval. Replacement IR and CO2 sensors have an unlimited shelf life, carry a two-year warranty and have an expected service life of five years or more.
Key Features
The Oldham OLCT 710 provides the following advantages for fixed gas detection:
- Flameproof junction box with terminal blocks and optional surge protection, certified as a complete Ex d assembly.
- Electropolished 316 stainless steel construction and IP66 protection for coastal and offshore atmospheres.
- Choice of infrared hydrocarbon, infrared CO2, catalytic bead or solid-state H2S plug-in sensors.
- SIL2 certification according to IEC 61508 for use in safety instrumented systems (except CO2).
- Non-intrusive magnetic calibration with fully scripted auto zero and auto span instructions.
- Simultaneous 4-20 mA and Modbus RS-485 outputs for controllers, PLCs and DCS systems.
- Pre-emptive fault diagnostics covering supply voltage, temperature, signal amplitude, loop integrity and sensor life.
- Wide operating temperature range of -40 to +75 °C.
Industrial Applications
The Oldham OLCT 710 is suited to wellheads, gathering stations, compressor and pumping stations, gas processing and treatment units, tank farms, loading facilities, refineries and petrochemical plants. Infrared hydrocarbon sensors suit areas where catalytic sensors could be poisoned by corrosive gases or where oxygen may be absent, while the solid-state H2S sensor is designed for sour gas facilities with high temperatures and changing humidity. The CO2 version monitors carbon dioxide in enclosed process and utility areas.
For Oman, this makes the Oldham OLCT 710 a strong fit for sour gas fields in the interior, export terminals and refineries on the coast, desalination and wastewater plants, and industrial projects in the Sohar, Duqm and Salalah zones. Seven Star LLC supplies the detector together with complementary fire and gas equipment such as the Oldham OLCT 100 fixed gas detector, the Oldham MX 62 gas detection controller and the Honeywell Sensepoint XRL gas detector.
Technical Specifications
The Oldham OLCT 710 values below are taken from the Teledyne Oldham Simtronics OLCT 700/710 brochure.
| Parameter | Specification |
|---|---|
| Model | Oldham OLCT 710 (OLCT 700 sensor module with flameproof junction box); IR, FP and TP versions |
| IR version | Combustible hydrocarbons 0-100% LEL or CO2 0-5% vol (standard ranges) |
| FP version | Matched pair catalytic bead, combustible gas 0-100% LEL |
| TP version | H2S solid-state metal oxide semiconductor, 0-20, 0-50, 0-100 or 0-200 ppm |
| Accuracy | FP and IR: ±3% LEL (0-50% LEL), ±5% LEL (50-100% LEL); TP: ±10% of reading or ±2 ppm; IR-CO2: ±5% FS |
| Response time | FP and IR-CH: T50 <10 s, T90 <30 s; TP: T50 <30 s, T80 <60 s; IR-CO2: T50 <15 s, T90 <40 s |
| Operating temperature | -40 to +75 °C |
| Input voltage / power | 11.5 to 28 VDC; <2 W typical |
| Outputs | Linear 4-20 mA DC; RS-485 Modbus RTU |
| Dimensions (OLCT 710) | 349 mm H × 127 mm W × 130 mm D |
| Weight (OLCT 710) | 3.36 kg aluminium version; 7.44 kg stainless steel version |
| Approvals | ATEX II 2G Ex d IIB+H2 T4 Gb; SIL2 to IEC 61508 (except CO2) |
| Warranty | 2 years electronics; 2 years IR and catalytic sensors; 5 years H2S sensor |
How to Order
To order the Oldham OLCT 710, send Seven Star LLC an RFQ with the target gas, range, sensor technology, junction box material and whether you need the surge protection module, together with the controller or DCS it will connect to. Our team in Muscat will confirm the part number, availability and lead time, and the OLCT 700/710 brochure can be downloaded from this page. Seven Star LLC supplies Teledyne Oldham Simtronics gas detection across Oman and the GCC with engineering support in Muscat.
- Brochure Oldham OLCT 700 / OLCT 710 Fixed Gas Detection Brochure Download
Oldham gas detector models listed here
The page lists the Oldham OLCT 100 fixed gas detector, including its infrared version, the OLCT 710 fixed gas detector and the MX 62 gas detection controller. The OLCT 100 is a 4-20 mA transmitter family offered for combustible gases, toxic gases and oxygen, depending on the sensor fitted, while the OLC 100 variant has a Wheatstone bridge output. The MX 62 takes the signals from the detectors, and applies the configured alarm logic.Ordering an Oldham sensor or detector: what we need
Send the reference number from the detector label, the gas and measuring range, and the hazardous-area marking. For a replacement Oldham sensor, add the detector version and the number printed on the cell, since sensor blocks differ between versions. For an MX 62, list the number and type of detector inputs, the modules fitted, and the supply voltage. Projects in the GCC that need a specific approval should state it.Browse Oldham products by category: Fire & Gas Detector, Logic Controller.
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