Honeywell Minipeeper C7035A

The Honeywell Minipeeper® Ultraviolet Flame Detectors, including models C7027A, C7035A, C7044A, and C7927A, are designed to detect ultraviolet (UV) radiation emitted by combustion flames. These detectors are integral components of Honeywell flame safeguard controls, providing flame supervision for gas, oil, or combination gas-oil burners.

Function Description

The primary function of these detectors is to sense the presence of a flame by detecting its UV radiation. This signal is then fed to a flame safeguard control, which uses it to ensure safe burner operation. If the flame is not detected when expected, or if it extinguishes unexpectedly, the control system will initiate a safe shutdown. The C7027A, C7035A, and C7044A models are compatible with RA890G devices or R7249A, R7290A, R7749B, and R7849A,B Amplifiers, as well as appropriate Honeywell controls. The C7927A is specifically designed for use with the R7851B Flame Amplifier and the 7800 SERIES controls.

Important Technical Specifications

Flame Detection: All models detect UV radiation. The C7035A offers end viewing, while the C7044A housing has two openings for either side or end viewing, with side viewing being 1/8 as sensitive as end viewing.
Ambient Operating Temperature Ratings:
- C7027A: 0°F to 215°F (-18°C to 102°C), or -40°F to 215°F (-40°C to +102°C), depending on model.
- C7035A: 0°F to 250°F (-18°C to +121°C), or -40°F to 250°F (-40°C to +121°C), depending on model.
- C7927A1016: -40°F to +200°F (-40°C to +93°C).
Storage Temperature Rating (C7927A): -20°F to +120°F (-28°C to +49°C).
Maximum Pressure Rating: All models are pressure rated for 5 psi (34.5 kPa).
Mounting:
- C7027A/C7927A: Integral collar threaded (internal 1/2-14 NPSM) for mounting on a 1/2-inch sight pipe.
- C7035A: Integral collar threaded (internal 1-11-1/2 NPSM) for mounting on a one-inch sight pipe. The DIN approved C7035A1064 has 1-11 BSP.P1 threads.
- C7044A: Mounts with a two-screw bracket (included in the Bag Assembly).
Wiring Connections:
- C7027A: Two 8 ft (2.44 m), color-coded, plastic-insulated, 18 AWG, NEC Class 1 lead wires, rated for 221°F (105°C). Rear has a clamp type connector for 1/2 in. flexible metallic conduit. Models are available with 1/2 in. internally threaded spud connector. C7027A1064 has 24 ft (7.32 m) lead wires. C7027A1114 has 44 in. (1.118 m) lead wires and 22 in. (558 mm) flexible conduit.
- C7035A: Two 6 ft (1.83 m), color-coded Silicon Rubber Insulated 18 AWG, NEC Class 1 lead wires rated for 302°F (150°C). Rear has 1/2-14 NPSM internal threads for conduit connection. The DIN-approved C7035A1064 has 1/2-14 BSP-F threads. C7035A1056 has 12 ft (3.66 m) leadwires. C7035A1080 has 10 foot (3 Meter) leadwire rated for 600°F (316°C).
- C7044A: Two 8 ft (2.44 m) color-coded, plastic coated 18 AWG, NEC Class 1 lead wires. Rear has a clamp type connector for 1/2 in. flexible metallic conduit.
- C7927A: Two 8 ft (2.4 m) color-coded, plastic coated 18 AWG, NEC Class 1 lead wires. Rear has a 1/2-in. spud-type connector.
Approvals: Underwriters Laboratories Inc. (listed: File No. MP268), Canadian Standards Association certified (Master Report LR 95329-1), Factory Mutual approved, Swiss Re (formerly Industrial Risk Insurers) acceptable. C7927A is cUL listed (MP268, Volume 30 and 31) and FM Approved (report number 3011020, June 26, 2002).
C7035A Housing: Meets Underwriters Laboratories Inc. requirements for rain tightness and complies with NEMA enclosure standards, types 4 and 4X.
C7927: Immune to x-ray testing.

Usage Features

Compact Size (C7044A): Particularly suitable for blast tube mounting.
Side or End Viewing (C7044A): Offers flexibility in flame monitoring applications.
Field Replaceable Sensor Tube (C7035A): The ultraviolet radiation sensor tube can be replaced in the field. For C7027A, C7044A, and C7927A, the sensing tube is not field replaceable, requiring replacement of the entire detector.
Parallel Wiring: Two C7027A, C7035A, or C7044A Flame Detectors can be wired in parallel for difficult flame sighting installations, reducing nuisance shutdowns. Note that C7927 cannot be used in parallel. When paralleling, the minimum ambient operating temperature must be increased to 32°F (0°C) for detectors rated for 0°F (-18°C), or to -10°F (-23°C) for detectors rated for -40°F (-40°C).
Ignition Spark Response Mitigation: For C7027A, C7035A, and C7044A applications where ignition spark response cannot be avoided, the Q624A or Q652B Solid-State Ignition Transformer can be used to alternately activate the spark generator and the UV sensing tube, preventing false flame signals.
Sight Pipe Installation: A black iron pipe is recommended for the sight pipe. It should be located to provide a clear line-of-sight to the flame, preferably tilting downward to prevent soot or dirt buildup. The pipe length and sighting angle are critical and should be determined during installation.
Sight Pipe Ventilation: Ventilation may be necessary to cool the detector or clear the sight pipe of UV-absorbing substances. For negative pressure chambers, drilling holes in the sight pipe or using a perforated nipple allows air flow. For positive pressure chambers, pressurized air from the burner blower can be connected to the sight pipe.
Heat Block (Accessory): The 136733 Heat Block is available for C7027A or C7927A when sight pipe temperatures exceed 215°F (102°C) but are below 266°F (130°C).
Swivel Mount (Accessory): The 118367A Swivel Mount facilitates proper sighting adjustments.
UV Sensor Tube Life Expectancy: The C7027, C7035, and C7044 ultraviolet radiation sensing tubes have a life expectancy of 40,000 hours of continuous use within specified ambient temperature and voltage ratings. When a tube wears out, it will fail to properly discriminate between flame conditions.
Burner Cycling: These detectors should only be used on burners that cycle on/off or are periodically checked for proper operation. Industry guidelines suggest one burner cycle in a 24-hour period.
Earth Ground: The detector and flame safeguard control must be connected to earth ground, typically via a flexible conduit or a good ground connection at the mounting bracket.
Wiring Considerations: Lead wires should be kept as short as possible to minimize capacitance. Splices, if needed, should be made in a junction box using moisture-resistant no. 14 wire. F and G wires must be run in their own conduit, separate from other power-carrying lead wires. Shielded twisted pair wire can be used for the F leadwire, with the shield grounded to the G terminal at the flame safeguard wiring subbase. Scanner wires should be separated a minimum of two inches (51 mm) from other line voltage wires in the main control panel.

Maintenance Features

Periodic Cleaning: The viewing window and sight pipe (if used) should be cleaned periodically with a soft, clean cloth to remove contaminants from the UV radiation sensor tube glass envelope.
Sensor Tube Replacement: For C7035A, the ultraviolet sensing tube can be replaced. For C7027, C7927, or C7044, the entire detector should be replaced at appropriate intervals based on the 40,000-hour life expectancy.
System Adjustment: The flame detection system should be kept adjusted for smooth, reliable operation as recommended by the burner manufacturer.
C7044A Cleaning Procedure: To clean the C7044A, loosen the two screws holding the mounting bracket to the blast tube, twist the bracket and detector to remove, clean the viewing window, and then reinsert and tighten the screws. The clamp screw on the bracket should not be loosened.