Product Mockup 1
Product Mockup 1
Product Mockup 1
Red1 Breakdown
Red1 Breakdown
Red1 Internals
Red1 Internals
Red1 In White
Red1 In White

(RED1-420)

The 4-20 mA RED1

Explosion-proof flame detection with analog 4–20 mA output for simple compatibility.

Let’s Talk Specs

Designed for Seamless 4–20 mA System Integration

The RED1-420 replaces relay outputs with an industry-standard 4–20 mA current loop interface. Detection performance, optical self-test, and hazardous area approvals remain identical to the RED1 platform.

Output states: 0 mA (Fault), 4 mA (Normal), 12 mA (Fire), 20 mA (Verified Fire).

This configuration is selected when the control architecture is built around DCS or PLC analog inputs, when relay-to-analog signal converters need to be eliminated, or when retrofit and brownfield projects require direct loop compatibility.

Specification Sheet Installation Manual

Key Features

  • 4–20 mA Analog Output: 0 mA Fault / 4 mA Normal / 12 mA Fire / 20 mA Verified Fire. No relay outputs on this model.

  • Verify Fire Function: Field-adjustable certainty levels (0–7) with approximately 5 seconds of delay per level. Can be disabled or set to trigger in parallel with Fire Mode.

  • Multi-Spectrum Sensing: UV (185–260 nm), IR (0.715–3.5 µm), and Visible (480–560 nm) sensors with optical self-test.

  • NEMA 4X Explosion-Proof Housing: Class I Div 1 & 2 Groups B, C, D · Class II Div 1 & 2 Groups E, F, G · Class III.

Confirm 4–20 mA Compatibility for Your Project

If your project requires analog output or integration into a DCS or PLC-based system, Sierra can help confirm loop configuration and signaling compatibility.

Let’s Talk Specs

The Engineering Behind the RED1-420

The RED1-420 uses the same proprietary multi-spectrum detection algorithm as the rest of the RED1 family. The difference is output: not detection.

Instead of relay contacts, the RED1-420 communicates detector status through a continuous current draw interface. The four output states (0, 4, 12, and 20 mA) map directly to Fault, Normal, Fire, and Verified Fire modes, giving control systems a clean analog signal without intermediate conversion hardware.

The Verify Fire function operates identically to the Enhanced models: after Fire Mode is triggered, the algorithm evaluates flame signature certainty over time. Seven configurable levels are available via DIP switch, or the function can be disabled entirely.

What Sets Sierra Apart

Sierra Safety Technology has manufactured flame detection equipment for nearly 40 years with zero product recalls and zero failures resulting in loss of life. RED1 units installed over 30 years ago remain in active service today.

The RED1-420 brings that same track record to analog-integrated systems: no signal converters, no additional hardware, no unnecessary complexity.

Specialized Applications Across Sectors

Oil & Gas

Refineries, offshore platforms, and fuel handling operations requiring FM-approved explosion-proof detection in Class I hazardous locations.

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Chemical

Petrochemical processing plants with volatile organic compounds, high-temperature reactions, and strict compliance requirements.

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Semiconductor

Fabrication and process areas where rapid detection of specialty chemical fires supports facility-wide safety systems.

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Technical Specifications Sheet

View available configurations, full product specifications, dimensions, and sensitivity ranges.

Download the Spec Sheet

Frequently Asked Questions

The RED1-420 uses a continuous current draw interface: 0 mA indicates Fault, 4 mA indicates Normal, 12 mA indicates Fire, and 20 mA indicates Verified Fire. There are no relay outputs on this model.

Yes. The Verify Fire function is configurable via DIP switch with seven levels of certainty, each adding approximately 5 seconds of delay. It can also be disabled or set to trigger in parallel with Fire Mode.

Any system that accepts 4–20 mA analog input: including distributed control systems (DCS), programmable logic controllers (PLC), legacy fire alarm panels, and plant-wide monitoring networks.

Yes, provided the existing loop is configured for 4–20 mA input. The detector connects without additional signal converters or interface modules.

Operating: −40°C to +85°C. Storage: −55°C to +110°C.

Two ¾-inch NPT feed-through hubs. Screw terminals accept 14–22 AWG wire. Dimensions are 5.4 × 4.8 × 3.7 inches (13.7 × 12.2 × 9.4 cm) at approximately 3 lbs.

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Standard

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Handheld Test Source

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