Landis & Gyr QRB1B-A070B70A Flame Detector

Landis & Gyr QRB1B-A070B70A Photoresistive Flame Detector

The Landis & Gyr (Siemens) QRB1B-A070B70A is a compact photoresistive flame detector engineered specifically for the supervision of yellow-burning oil flames in commercial, industrial, and marine boiler burners. Operating via a photo-conductive Cadmium Sulfide (CdS) sensor element, the detector measures visible light radiation emitted by the combustion process and transmits a direct resistance signal to an interlocking burner control unit.

The QRB1B-A070B70A variant features a specialized cylindrical mounting plug with a lateral clamping flange, an integrated protective sleeve, and a factory-fitted 700 mm 2-core connecting cable with 70 mm stripped and ferruled lead ends. It provides fail-safe flame monitoring under severe vibration and ambient thermal cycling common to auxiliary marine boilers, thermal fluid heaters, and heavy-fuel-oil (HFO/MDO) combustion plants.

Model Details:

• Manufacturer: Landis & Gyr / Siemens
• Model Code: QRB1B-A070B70A
• Base Series: QRB1 Series (Photoresistive Detectors)
• MPN / Ordering Code: BPZ:QRB1B-A070B70A

Technical Specifications

Key Features

1. Optimized Visible Light Spectrum: Tuned specifically for yellow-flame oil combustion (400–700 nm) to avoid false trips caused by refractory wall infrared afterglow.
2. Vibration-Resistant Flange Housing: Type “B” plug housing with retaining flange maintains axial focal alignment inside blast tubes subjected to marine engine-room vibrations.
3. Pre-Terminated 700 mm Lead: Factory-assembled 2-conductor cable with 70 mm stripped/ferruled ends prevents field wire degradation and reduces installation downtime.
4. High Signal-to-Noise Ratio: Rapid dark-to-light resistance transition enables immediate drop-out (< 1 second) during flame failure or atomization drop.
5. Interoperable Controller Support: Direct drop-in interface with multiple generations of Siemens, Landis & Gyr, and Landis & Staefa automatic burner control units.

Primary Applications

• Marine auxiliary steam boilers (Aalborg, KangRim, Miura, SAACKE).
• Marine inert gas generators (IGG) and thermal oil heaters.
• Industrial monoblock and dual-fuel package burners (Weishaupt, Riello, Oilon, Elco, Baltur).
• Commercial hot water and steam generation systems utilizing distillate (MGO/MDO) or residual fuel oils (HFO).

Compatible Control Boxes

• Siemens / Landis & Gyr LOA Series: LOA24.171B27, LOA24.173A27, LOA26.171B27, LOA36.171A27
• Siemens LMO Series: LMO14.113C2, LMO24.111C2, LMO24.255C2, LMO44.255C2
• Siemens LAL Series: LAL1.25, LAL2.25, LAL2.65, LAL3.25
• Siemens LOK / LGK Series: LOK16.250A27, LOK16.140A27 (when configured for intermittent yellow-flame monitoring)

Part Number Cross-References

• Siemens Ordering Number: BPZ:QRB1B-A070B70A
• Legacy Landis & Gyr Code: QRB1B-A070B70A / QRB1B-A070B70
• Burner OEM Equivalents:
  • Weishaupt Part No: 600 327 / 600 334
  • Riello Part No: 3007489 / 3007567
  • Elco Part No: 13008985

Frequently Asked Questions

What is the difference between QRB1A and QRB1B series detectors?

The difference lies in the mechanical housing and mounting style. The QRB1A comes with a smooth housing (without a securing flange) designed for insertion into push-fit clip brackets, whereas the QRB1B features a clamping flange with a locating groove intended for positive locking into blast tube guide tubes.

Can the QRB1B-A070B70A detector be used for blue-flame or natural gas burners?

No. The QRB1 series utilizes a CdS photoresistive cell sensitive only to visible light (400–700 nm, yellow flame). Blue-burning gas flames and low-NOx blue oil flames emit primarily in the ultraviolet (UV) spectrum (~200–280 nm) and require UV flame detectors such as the Siemens QRA2, QRA10, or ionization flame rods.

What does the designation “A070B70A” indicate?

In the Siemens/Landis & Gyr coding system, A070 denotes a 700 mm cable length, B specifies standard PVC cable insulation, and 70A indicates 70 mm stripped outer sheath with pre-crimped terminal ferrules.

Is the electrical connection polarity-dependent?

No. The QRB1 photoresistive cell acts as a pure variable resistor. The two signal wires can be wired to the corresponding controller terminals (e.g., terminals 11 and 12 on an LOA base) in either polarity without affecting operation.