TM 5-3895-374-24-2
FLAME SAFEGUARD
OPERATION - 45UV5 SELF-CHECKING UV SCANNER
Self-checking ultraviolet scanners should be used in applications where burner firing operation is
continuous or where the burner is on for long periods of time without recycling. In addition, ultraviolet self-
checking systems are mandatory in some locations.
The operation of this type of system consists of maintaining the flame scanning capability at all times while
also proving that the ultraviolet tube is firing properly. This is done periodically by mechanically closing off
the sight of the UV tube and checking to make sure that the flame signal goes away. A shutter assembly
in the 45UV5 scanner performs this function. The diagram below explains the process further.
If the shutter assembly in the scanner fails, the tube is faulty, or there is insufficient power to the scanner,
the FLAME-MONITOR will LOCKOUT and display the following message LOCKOUT CHECK SCANNER.
The ultraviolet tube is replaceable (P/N 4-314-1).
A lockout will result if a minimum signal is detected for three consecutive shutter closed periods.
WIRING - UV SCANNERS
To connect the scanner to the control, the UV I Scanner is supplied with 36" or 72" of flexible cable.
The 45UV5 is supplied with four 72 lead wires. Install them in a suitable length of flexible armor cable and
connect it to the control. A conduit connector is supplied with the scanner. Connect black wires (shutter)
to terminals L1, L2; red wires (UV tube) to terminals S1, S2.
If it is necessary to extend the scanner wiring, the following instructions apply:
Scanner wires should be installed in a separate conduit. The wires from several scanners may be
installed in a common conduit.
1.
Selection of Wire
a.
Use #14, 16 or 18 wire with 750C, 600 volt insulation for up to 100 foot distances (signal loss
approximately 20% at 100 feet).
b.
Extended Scanner Wiring: For extended scanner wiring up to 500 feet, and for shorter lengths to
reduce signal loss, use a shielded wire (Belden 8254-RG62 coaxial cable, or equal) for each
scanner wire of UV 1, UV2 and each red wire of the 45UV5. The ends of the shielding must be
taped and not grounded.
c.
Asbestos insulated wire should be avoided.
d.
Multiconductor cable is not recommended without prior factory approval.
2.
High voltage ignition wiring should not be installed in the same conduit with flame detector wires.
INSTALLATION - INFRARED SCANNER TYPE 48PT2
Where possible, obtain the burner manufacturer’s instructions for mounting the scanner, otherwise
proceed as follows:
A single scanner is used to detect both pilot and main flames. The sight pipe on which the scanner
mounts must be aimed so that the scanner sights a point at the intersection of main and pilot flames.
Proper scanner positioning must assure the following:
a.
Reliable pilot flame signal.
b.
Reliable main flame signal.
c.
A pilot flame too short or in the wrong position to ignite the main flame reliably, must not be
detected.
d.
Scanner must have an unobstructed view of flame being monitored.
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