Table of Contents

Introduction

Every industrial gas-detection project eventually asks the same question: do we buy fixed detectors, portable detectors, or both? The honest answer is almost always both — but the mix, the channels and the architecture depend on the process, the workforce and the regulatory framework. For EHS managers, plant engineers and procurement teams in Russia and the Middle East, getting this balance right determines whether a site is genuinely protected or simply carries insurance paperwork.

This guide compares fixed and portable gas detectors head to head, explains where each one belongs, shows how a controller ties them together, and outlines a practical selection path for EAC (TR CU 012/2011), ATEX and IECEx-oriented projects.

What Each Category Does

A fixed gas detector is a permanently installed instrument mounted at a defined point — a flange, a pump seal, a sump, a compressor — that monitors that location 24 hours a day and sends its signal to a controller, DCS or PLC. It watches a place.

A portable gas detector is carried or worn by a worker. It monitors the atmosphere immediately around that person and alarms them personally if they walk into a hazard. It watches a person.

The two are not competitors; they answer different questions. Fixed detection protects the facility and triggers area-wide action; portable detection protects the individual and follows them into unknown atmospheres.

Side-by-Side Comparison

Criterion	Fixed gas detector	Portable gas detector
Coverage	Defined point, 24/7	Worn by worker; follows them
Typical signal	4–20 mA / RS485 / MBUS to DCS/PLC	On-board audible/visual/vibration alarm
Alarm action	Area alarm, ventilation, interlocks	Personal warning; must escape
Power	Wired / loop-powered	Rechargeable battery (hours)
Installation	Mounted, wired, commissioned	Distributed to each worker
Best for	Process areas, leak sources, unmanned zones	Confined-space entry, maintenance, patrols
Calibration	Periodic, often IR remote	Daily bump test; periodic span
Hangwei examples	HD9300 fixed	HD620 four-in-one / HD600 single-gas

Where Fixed Detection Belongs

Permanent, continuously operated process areas: compressor stations, pump houses, battery rooms, chlorinator rooms.
Known leak sources: flanges, valve manifolds, relief-valve discharges, loading arms.
Unmanned or low-manning areas where a worker may not be present to hear a personal alarm.
Zones requiring automatic ventilation, isolation or shutdown interlocks through dual relay outputs.

The HD9300 fixed detector is designed for exactly these roles. It is rated Ex d IIC T6 Gb, operates from –40 °C to +70 °C, transmits 4–20 mA / RS485 / MBUS to DCS/PLC, carries dual alarm relays, and supports IR remote calibration so the user does not need to open the flameproof enclosure in the field.

Where Portable Detection Belongs

Confined-space entry: tanks, vessels, sewers, sumps and pits.
Maintenance, turnaround and inspection work in areas that are not continuously manned.
Mobile crews: welders, technicians, patrol operators, cleaners.
Leak search and atmospheric verification before opening a process connection.

The HD620 four-in-one portable is the standard oil-and-gas and confined-space instrument: it measures H2S, CO, O2 and LEL on a 2.4-inch colour screen, is rated Ex ia IIC T4 Ga and IP65, runs about 20 hours on a 5,000 mAh battery, and combines audible, visual and vibration alarms with English and Chinese voice prompts. For a single known gas, the HD600 single-gas portable is the lighter, lower-cost choice.

The Controller Ties It Together

A fixed detection system is only as good as its controller. The HD600 gas alarm controller handles from 2 to 128 detector channels over 2-, 3- or 4-wire loops, with LCD or colour display, and turns detector signals into area alarms, ventilation starts and operator actions. For a single room or equipment corner, the HD6100 single-point wall-mounted all-in-one controller combines a detector, display and local alarm in one enclosure.

See the fixed detector: HD9300 Fixed Gas Detector with LCD Display

See the controller: HD600 Fixed Gas Alarm Controller (2–128 channels)

See the single-point controller: HD6100 All-in-One Controller

See the portable detector: HD620 Four-In-One Pump Portable Gas Detector

How to Choose: A Practical Selection Path

Map every hazard source and decide which locations must be watched continuously — those get fixed detectors.
Map every worker who enters an uncontrolled or confined atmosphere — each needs a portable.
Choose channels to match the hazard: H2S/CO/O2/LEL for oil and gas; dedicated Cl2, SO2, NH3 or CO2 where the process demands it.
Size the controller to current and future channels (the HD600 scales from 2 to 128) and plan DCS/PLC integration via 4–20 mA / RS485 / MBUS.
Confirm explosion protection: Ex d IIC T6 Gb for fixed, Ex ia IIC T4 Ga for portable, with EAC/ATEX/IECEx documentation.

Why Source the Whole System from One Manufacturer

Mixing detectors from one brand and controllers from another creates commissioning pain, ambiguous warranty and slow support. A single supplier — with 20+ years of manufacturing, 20 patents, 10 production lines and proven OEM/ODM capability — delivers matched detectors, controllers, cabling philosophy and documentation. Hangwei Sensors supplies complete detector-plus-controller packages, custom sensor configurations, and actively recruits global distributors in Russia, the Middle East and beyond.

Start a custom project: Custom Gas Sensor & Detector Solutions

FAQ

Is fixed detection enough without portable devices?

No. Fixed detectors watch a location, but a confined space or a maintenance route is not permanently covered. Every entrant carries a personal portable, even where fixed points exist.

Are portable detectors enough on their own?

No. A personal alarm only helps when a worker is present. Unmanned areas, continuous process zones and interlocked ventilation need fixed detection that acts automatically.

How many channels does a controller need?

Start with the number of fixed points and add 20–30% headroom for expansion. The HD600 scales from 2 to 128 channels, so growth is a matter of adding detectors, not replacing the controller.

Do fixed and portable detectors use the same sensors?

Often the same sensor chemistry, but packaged differently. Fixed detectors prioritise long life, wiring and relay output; portables prioritise battery, size and personal alarm.

What explosion protection should I specify?

For fixed instruments in gas-hazard areas, Ex d IIC T6 Gb (as on the HD9300); for personal instruments, Ex ia IIC T4 Ga (as on the HD620). EAC (TR CU 012/2011), ATEX and IECEx documentation should be planned at specification stage.

Can Hangwei supply a complete, custom system?

Yes. Hangwei supplies detectors, controllers, custom sensor ranges and packaged systems, with OEM/ODM and global distributor programmes — contact our engineering team to scope your site.

Get Expert Guidance

Specifying a fixed-and-portable gas detection system is a safety-critical, commercial decision. Hangwei Sensors designs and manufactures fixed detectors, portable gas detectors and controllers for oil and gas, petrochemical, water treatment, refrigeration and general industry across Russia, the Middle East and worldwide. Whether you need a single detector, a 128-channel controller, a custom sensor package or an OEM/distributor partnership, our engineers will scope the right architecture.

Email: hw@hangweisensors.com | Phone: +86 371 6667 0886

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