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Overview
A fixed gas detector installed in a plant room, process area, or confined space entry point is only one half of a complete gas detection system. The detector measures gas concentration and outputs a signal — but without a controller to receive that signal, process it against alarm thresholds, activate audible and visual alarms, and trigger relay outputs to safety systems, that signal goes nowhere useful. The controller is what converts a raw sensor reading into a safety response: sounding the alarm, switching on ventilation, tripping a process, or sending data upstream to a SCADA system or building management platform.
The BH-KZ101 gas alarm control panel is a wall-mounted gas detection controller designed to receive signals from one or more fixed gas detectors, display real-time gas concentration on a high-definition LCD screen, and activate a two-level sound and light alarm system and three independent relay output channels when preset alarm thresholds are breached. It accepts both the industry-standard 4–20mA analogue signal and RS485 digital signal inputs from any compatible fixed gas transmitter — making it a universal controller that integrates with the vast majority of fixed gas detectors currently in use across industrial facilities, without requiring a proprietary detector from the same manufacturer.
Manufactured by Bosean Electronic Technology Co., Ltd. and supplied by Alright Engineering Solutions Pte Ltd — Singapore-based authorised distributors of fixed gas detection equipment serving the maritime and industrial sectors across the Asia-Pacific region — the BH-KZ101 stands out from basic alarm relay panels through its MODBUS protocol support on the RS485 digital interface. MODBUS is the de facto standard communication protocol for industrial instrumentation integration with SCADA systems, DCS platforms, and building management systems — meaning the BH-KZ101 does not just alarm locally, it communicates digitally upstream into the facility’s data management infrastructure, providing timestamped alarm event data and real-time concentration values to any connected supervisory platform.
Key Features
1. Dual Signal Input — 4–20mA Analogue and RS485 Digital (MODBUS)
The BH-KZ101 accepts both 4–20mA analogue and RS485 digital signal inputs simultaneously, giving it compatibility with the full range of fixed gas transmitters currently in use across industrial facilities. The 4–20mA input is the universal standard for analogue gas transmitter signals — a 4mA output from the transmitter indicates zero concentration, 20mA indicates full-scale, and any value in between maps linearly to the corresponding gas concentration. The RS485 digital input with MODBUS protocol support allows the BH-KZ101 to receive higher-resolution digital data from compatible digital gas transmitters — including concentration value, alarm status, sensor diagnostic information, and device identifier — providing more information than the analogue signal alone. For new installations specifying digital transmitters, the RS485 MODBUS input future-proofs the controller for integration with more advanced detector technology without requiring panel replacement.
2. Two-Level Sound and Light Alarm — 65dB to 100dB Audible Output
The BH-KZ101 provides a two-stage alarm system with independently configurable Low and High alarm concentration thresholds. When gas concentration exceeds the Low alarm setpoint, the first-level sound and light alarm activates — alerting workers in the area to an elevated gas condition and prompting investigation before concentrations reach a more dangerous level. When the High alarm threshold is breached, the second-level alarm activates with increased urgency, simultaneously triggering the configured relay outputs for automatic safety system responses. The audible alarm output ranges from 65dB to 100dB at 1 metre — adjustable to suit the ambient noise level of the installation environment, from quiet office-adjacent plant rooms to loud industrial processing areas. The visual alarm indicator provides a simultaneous optical alert visible across a large area for workers who may not hear the audible signal due to noise or hearing protection.
3. Three Sets of Relay Contact Outputs — 30V DC / 3A, 250V AC / 3A
The BH-KZ101 provides three independent sets of relay contact outputs, each rated at 30V DC / 3A and 250V AC / 3A. Three relay channels allow a fully staged automated safety response to be configured: one relay for local audible/visual alarm activation, one for automatic ventilation fan control, and one for process shutdown, solenoid valve closure, or emergency system activation — all triggering in the appropriate sequence as gas concentration rises through the alarm levels. The relay contacts are free-contact (volt-free) outputs, meaning they can be wired into circuits at any voltage within the relay’s rating — DC or AC — without the BH-KZ101’s internal circuitry being affected by the external circuit voltage. This makes the relay outputs directly compatible with the wide range of voltages and circuit types found in industrial safety and building management systems.
4. High-Definition LCD Display with Status Indicators
The BH-KZ101’s front panel features a high-definition LCD display that shows real-time gas concentration values from connected detectors alongside system status indicators for alarm state, power, fault, and communication status. The display allows any operator or maintenance technician to read current gas levels directly at the controller panel without accessing a separate SCADA terminal or monitoring computer — useful during commissioning, maintenance rounds, and incident response when immediate on-site concentration data is needed. Status indicator LEDs provide at-a-glance system health information: power-on status, alarm activation state, communication link status, and fault conditions are all visible simultaneously from the front panel without opening the enclosure or navigating menus.
5. RS485 MODBUS Digital Upload — Integration with SCADA and Building Management Systems
The BH-KZ101 supports two-way RS485 communication using the MODBUS protocol for upstream digital data transmission to supervisory systems. MODBUS is the most widely supported communication protocol in industrial instrumentation — compatible with SCADA systems, DCS platforms, building management systems, and industrial computers from virtually all major automation vendors, without proprietary gateway hardware or protocol converters. Through the MODBUS interface, the BH-KZ101 transmits real-time gas concentration values, alarm status, and event data to the connected supervisory system, enabling centralised monitoring, automated alarm logging, and integration with facility-wide safety management platforms. Two-way communication also allows alarm setpoints and configuration parameters to be adjusted remotely from the supervisory system — without requiring physical access to the controller panel.
6. DC 24V Output Supply — Powers Connected Gas Detectors
The BH-KZ101 provides a DC 24V output to power connected fixed gas transmitters directly from the controller, eliminating the need for separate power supplies at each detector location. This simplifies the installation wiring significantly: a single cable run from the controller to each detector carries both the 24V power supply and the 4–20mA or RS485 signal, reducing the total wiring infrastructure required for a complete detection system. The controller’s system power consumption is rated at 25W or less — appropriate for wall-mounted enclosure installation on a standard single-phase supply circuit.
7. Wall-Mounted Compact Enclosure — Simple Field Installation
The BH-KZ101 is housed in a compact wall-mounted enclosure measuring 31×21×8cm and weighing approximately 2900g — sized and weighted for straightforward single-person installation on a wall or equipment panel. The front-panel interface provides access to all configuration and operational functions without requiring the enclosure to be opened during normal use, keeping internal wiring and terminals protected. Working temperature range is 0°C to +40°C, suitable for installation in control rooms, equipment rooms, electrical panels, and protected industrial enclosures where ambient temperature is managed within this range.
Technical Specifications
Model: BH-KZ101 Gas Controller (Bosean — Supplied by Alright Engineering Solutions Pte Ltd)
Display: High-definition LCD display + status indicator LEDs
Signal Input: 4–20mA analogue; RS485 digital signal
Signal Output: Three sets of relay contact outputs — 30V DC / 3A and 250V AC / 3A (free contact)
Digital Upload Protocol: Two-way RS485; MODBUS protocol support
Output Voltage: DC 24V (for powering connected gas detectors)
System Power: ≤25W
Alarm: Two-level sound and light alarm; audible output 65dB–100dB at 1 metre
Working Temperature: 0°C to +40°C
Dimensions: 31×21×8cm
Weight: Approximately 2900g
Installation: Wall-mounted
Battery Life: Not applicable — mains powered continuous operation
IP Rating: Indoor enclosure — confirm specific IP classification with Alright Engineering Solutions for application requirements
Wireless Connectivity: None (RS485 hardwired MODBUS digital communication)
Data Logging: Via connected SCADA or supervisory computer through RS485 MODBUS interface
Compatible Detector Inputs: Any fixed gas transmitter with standard 4–20mA or RS485 MODBUS output — gas types including CO, H2S, O2, LEL, SO2, NH3, NO2, Cl2, H2, CO2, and others
Benefits
The most practical benefit of the BH-KZ101 for a facility deploying or upgrading a fixed gas detection system is its input signal universality. Because it accepts both 4–20mA and RS485 MODBUS signals, the BH-KZ101 is compatible with fixed gas detectors from Bosean and from virtually every other fixed gas transmitter manufacturer that outputs either of these standard signal types — which is to say, almost all of them. For facilities that have existing detectors from multiple suppliers, or that are adding new detectors to an existing installation, this universality means the BH-KZ101 can serve as a common controller for a mixed-manufacturer detector network without requiring signal conversion hardware or detector replacement.
The three relay output channels with high current ratings (3A AC/DC) allow the BH-KZ101 to drive external safety devices directly — without intermediate relay amplifier panels that add cost, installation complexity, and potential failure points to the system. For a simple installation driving a local alarm beacon, a ventilation fan contactor, and a process shutdown relay, the BH-KZ101’s three outputs cover all three functions within a single controller — keeping the panel count and wiring complexity to a minimum.
The MODBUS RS485 digital upload interface connects the BH-KZ101 into the facility’s broader safety data management infrastructure. For HSE managers who need to demonstrate that gas monitoring data is being continuously collected, timestamped, and archived — as required under COSHH, Singapore’s WSH Act, and equivalent Asia-Pacific occupational health regulations — the MODBUS connection to a central SCADA or data logging system provides the automatic data collection pathway needed without manual transcription of alarm records. Two-way MODBUS also allows remote alarm setpoint management, which is operationally valuable in facilities where the controller may be installed in a location that is inconvenient to access physically for routine configuration changes.
The built-in DC 24V output supply for detector powering reduces the BOM (bill of materials) and installation cost of a complete gas detection system. In a typical installation, each detector location requires a 24V power supply in addition to the signal cable run. By powering detectors directly from the BH-KZ101, the separate power supply hardware and its associated installation wiring, conduit, and panel space are eliminated — a material cost saving that becomes more significant as the number of detector points in the system increases.
Who It’s For
Electrical and Instrumentation Engineers Designing Fixed Gas Detection Systems: If you are specifying a fixed gas detection system for a new facility or upgrading an existing installation, the BH-KZ101 provides a controller that accepts standard industry signal types, outputs standard relay contacts, and communicates via standard MODBUS — allowing it to be integrated into a system design without requiring proprietary components or custom interfaces. The DC 24V detector power output simplifies the wiring design by reducing the number of separate power supply panels required, and the three relay channels cover the typical three-output alarm logic (local alarm, ventilation, shutdown) from a single controller.
HSE Managers and Safety Officers in Facilities with Existing Fixed Detectors: If your facility already has fixed gas detectors installed — possibly from multiple manufacturers — but lacks a centralised controller with MODBUS connectivity for data management, the BH-KZ101’s universal 4–20mA and RS485 input compatibility means it can integrate with existing detectors without requiring replacement. The addition of a MODBUS-connected controller upgrades an existing local-alarm-only installation to a system capable of feeding gas concentration and alarm data into a SCADA or building management system — improving both the facility’s real-time awareness and its compliance documentation capability without the cost of replacing the entire detector infrastructure.
Facility Managers in Marine, Commercial, and Industrial Buildings: For building services managers responsible for gas monitoring in enclosed spaces — engine rooms, generator rooms, LPG storage areas, car park ventilation systems, boiler rooms — the BH-KZ101 provides a wall-mountable controller that can be installed in a plant room or electrical panel room, connected to fixed detectors in the hazardous areas via standard signal cable, and integrated with the building management system via MODBUS RS485. The two-level alarm with audible output up to 100dB and three relay outputs for alarm devices, ventilation, and safety systems covers the full local response requirement from a single compact panel.
Possible Applications
Centralised Gas Alarm Control in Oil and Gas Processing Facilities: Controller hub for multiple fixed gas transmitters monitoring H2S, LEL, CO, and O2 across process areas — receiving transmitter signals, displaying zone concentrations, and triggering relay outputs to the facility’s PA system, ventilation controls, and emergency shutdown system on alarm.
Marine Vessel Gas Monitoring Panels: Wall-mounted gas detection controller for shipboard applications — receiving signals from fixed detectors in engine rooms, cargo pump rooms, battery spaces, and accommodation spaces, and activating local alarms and ventilation controls through relay outputs when gas concentrations exceed safe levels.
Building Management Integration — Commercial and Industrial Facilities: MODBUS RS485 interface to building management systems (BMS) for facilities requiring centralised, real-time gas concentration monitoring across multiple zones — car parks (CO), plant rooms (combustibles), battery rooms (H2), and any other occupied or monitored space with gas hazard monitoring requirements.
Wastewater Treatment Plants — Multi-Point H2S and Methane Monitoring: Central alarm controller for a network of fixed H2S and methane detectors across treatment plant buildings, pump stations, and access points — providing a single control point for all gas monitoring alarm management and SCADA integration in a multi-building treatment facility.
Chemical Storage and Handling Facilities: Gas detection controller for fixed transmitters monitoring toxic and combustible gas concentrations in chemical warehouses, drum stores, and handling areas — with relay outputs configured to activate emergency ventilation and automatic door closure systems on alarm.
Mining Surface Infrastructure and Headframe Buildings: Gas detection control panel for above-ground infrastructure at mining operations — winding engine houses, compressor buildings, workshop areas — where gas monitoring is required with relay outputs to building ventilation and personnel alarm systems.
Power Generation Plant Rooms and Substations: Controller for fixed H2, SF6, or combustible gas detectors in transformer halls, battery rooms, and generator enclosures — with MODBUS connectivity to the plant’s DCS or energy management system for integrated gas monitoring and alarm management.
Refrigeration and Cold Storage Plant Rooms: Gas alarm controller for ammonia (NH3) or hydrocarbon refrigerant fixed detectors in refrigeration machinery rooms — activating emergency ventilation, closing refrigerant isolation valves, and triggering personnel evacuation alarms through relay outputs when refrigerant leak concentrations reach alarm thresholds.
Trust and Certifications
MODBUS Protocol Compliance: MODBUS is the most widely adopted open communication protocol in industrial automation and instrumentation, used by hundreds of thousands of devices from thousands of manufacturers globally. MODBUS RTU over RS485 is the standard digital interface for gas detection controllers in industrial installations, ensuring the BH-KZ101 is compatible with SCADA systems, DCS platforms, and industrial computers from all major automation vendors without requiring protocol converters, gateways, or proprietary software. Two-way MODBUS communication means the BH-KZ101 both transmits data upstream and receives configuration commands from the supervisory system — supporting remote setpoint management without physical panel access.
Standard 4–20mA Signal Compatibility: The 4–20mA analogue input is the universal industry standard for process instrumentation signal transmission, compatible with fixed gas transmitters from all major manufacturers. This compatibility ensures the BH-KZ101 can serve as a controller for virtually any 4–20mA gas transmitter currently in production or installed in existing facilities — avoiding the vendor lock-in of proprietary-signal detection systems.
Relay Output Ratings — 30V DC / 3A and 250V AC / 3A: The relay output ratings confirm the BH-KZ101’s relay contacts are suitable for direct connection to both low-voltage DC control circuits and standard 230V AC supply circuits for directly driving alarm beacons, ventilation fan contactors, and process control devices without intermediate relay amplification in most installations.
Bosean Electronic Technology Co., Ltd.: Bosean is a specialist gas detection manufacturer founded in 2013, producing a comprehensive range of fixed gas detectors, portable gas monitors, gas alarm controllers, and environmental monitoring instruments for industrial, commercial, and safety-critical applications globally. Bosean operates under the ISO9001 quality management system and maintains a production and R&D base of over 10,000 m² with a team of nearly 100 R&D engineers. The BH-KZ101 is part of Bosean’s fixed gas alarm controller product line, supported by full technical documentation and global distribution through authorised distributor partners.
Alright Engineering Solutions Pte Ltd — Authorised Distributor: Alright Engineering Solutions is a Singapore-based engineering solutions company serving the maritime and industrial sectors across the Asia-Pacific region. As an authorised distributor of fixed gas detection and gas alarm control equipment, Alright Engineering Solutions provides full product support including supply, installation guidance, system integration advice, and after-sales service. Full product portfolio available through alrightes.com.
Warranty: Available on request through Alright Engineering Solutions. Controller hardware warranty terms and conditions documented in the product manual supplied with each unit.
Accessories and Variants
Compatible Fixed Gas Transmitters (4–20mA or RS485 Output): The BH-KZ101 integrates with any fixed gas transmitter outputting a standard 4–20mA or RS485 MODBUS signal — including Bosean’s own fixed detector range (BH-60, K-G60, GTQ-DX401, GT-K90, BH-DX 103-TSP) and third-party detectors monitoring CO, H2S, O2, LEL, SO2, NH3, NO2, CO2, Cl2, H2, and other gases. Alright Engineering Solutions can supply matched detector-controller packages configured for your specific gas monitoring requirements.
Audible/Visual Alarm Beacon (External): External alarm beacon devices — horn sounders, strobe lights, or combined horn/strobe units — wired to the BH-KZ101’s relay outputs provide additional alarm coverage beyond the controller’s built-in alarm in large areas, noisy environments, or locations distant from the controller panel. Available in weatherproof and explosion-proof variants for outdoor and hazardous area installation.
RS485 to USB / RS485 to Ethernet Converter: For facilities connecting the BH-KZ101’s RS485 MODBUS output to a PC-based data logging system or Ethernet-networked SCADA platform, RS485 interface converters provide the signal conversion needed without replacing the controller or its wiring.
Signal Cable — 3-Core and 4-Core Shielded Instrumentation Cable: Standard 3-core shielded cable for 4–20mA wiring runs from BH-KZ101 to connected detectors; 4-core shielded cable for RS485 wiring. Available locally or through Alright Engineering Solutions for turnkey supply.
Available Variants:
BH-KZ101 (this model): Single-zone wall-mounted gas alarm controller — 4-20mA and RS485 MODBUS input, 3 relay outputs, DC 24V detector power supply, LCD display
Multi-channel gas alarm control panels for larger installations (multiple detector zones) are available in the Bosean controller range — contact Alright Engineering Solutions to discuss channel count requirements and specify the appropriate controller for your system scale
Ready to Specify the BH-KZ101 for Your Gas Detection System?
Whether you are commissioning a new fixed gas detection installation, adding centralised alarm control to an existing detector network, or integrating gas monitoring data into a SCADA or building management platform via MODBUS, the BH-KZ101 provides the signal compatibility, relay output capacity, and digital communication capability that a complete gas detection system requires at its control centre.
To request a formal quotation, discuss system integration requirements, or get technical advice on detector selection, wiring design, and MODBUS configuration for your specific application, contact the Alright Engineering Solutions team directly. We support the full system specification and procurement process — from detector selection and controller configuration through to installation guidance, commissioning support, and SCADA integration assistance.
