HAMAMATSU R2868 Datasheet

Quick Detection of Flame from Distance,

Compact UV Sensor with High Sensitivity and Wide Directivity,

Suitable for Flame Detectors and Fire Alarms.

Hamamatsu R2868 is a UV TRON ultraviolet detector that makes
use of the photoelectric effect of metal and the gas multiplication
effect. It has a narrow spectral sensitivity of 185 to 260 nm, being
completely insensitive to visible light. Unlike semiconductor
detectors, it does not require optical visible-cut filters, thus
making it easy to use.
In spite of its small size, the R2868 has wide angular sensitivity
(directivity) and can reliably and quickly detect weak ultraviolet
radiations emitted from flame due to use of the metal plate
cathode (eg. it can detect the flame of a cigarette lighter at a
distance of more than 5 m.).
The R2868 is well suited for use in flame detectors and fire
alarms, and also in detection of invisible discharge phenomena
such as corona discharge of high-voltage transmission lines.

FLAME SENSOR

UV TRON® R2868

APPLICATIONS

● Flame detectors for gas/oil lighters and matches

● Fire alarms

● Combustion monitors for burners

● Inspection of ultraviolet leakage

● Detection of discharge

● Ultraviolet switching

GENERAL

Parameters Rating Units

Spectral Response 185 to 260 nm
Window Material UV glass —
Weight Approx. 1.5 g
Dimensional Outline See Fig. 3 —

MAXIMUM RATINGS

Parameters Rating Units

Supply Voltage 400 Vdc
Peak Current
Average Discharge Current
Operating Temperature -20 to +60 °C

CHARACTERISTICS (at 25°C)

Discharge Starting Voltage (with UV radiation)
Recommended Operating Voltage 325±25 Vdc
Recommended Average Discharge Current 100 µA
Background
Sensitivity

1)

2)

Parameters Rating Units

3)

4)

30 mA

1mA

280 Vdc Max.

10 cpm Max

5000 cpm Typ.

NOTES:

1) This is the maximum momentary current that can be handled if its full width
at half maximum is less than 10 µs.

2) If the tube is operated near this or higher, the service life is noticeably reduced.
Use the tube within the recommended current values.

3) Measured under room illuminations (approximately 500 lux) and recommended
operating conditions. Note that these values may increase if the following
environmental factors are present.

1. Mercury lamps, sterilization lamps, or halogen lamps are located nearby.

2. Direct or reflected sunlight is incident on the tube.

3. Electrical sparks such as welding sparks are present.

4. Radiation sources are present.

5. High electric field (including static field) generates across the tube.

4) These are representative values for a wavelength of 200 nm and a light input
of 10 pW/cm
ultraviolet radiation and the drive circuitry employed.

2

. In actual use, the sensitivity will vary with the wavelength of the

Figure 1: UV TRON’s Spectral Response and Various

Light Sources

TPT B0009EA

100

UV TRON s
SPECTRAL
RESPONSE

SUNLIGHT

50

(ARBITRARY UNIT)

0

RELATIVE SENSITIVITY, RELATIVE INTENSITY

200 300 400 500 600 700 800 900100

ULTRAVIOLET VISIBLE INFRARED

GAS
FLAME

WAVELENGTH (nm)

TUNGSTEN
LIGHT

Subject to local technical requirements and regulations, availability of products included in this promotional material may vary. Please consult with our sales office.

Information furnished by HAMAMATSU is believed to be reliable. However, no responsibility is assumed for possible inaccuracies or omissions.
Specifications are subjected to change without notice. No patent rights are granted to any of the circuits described herein. © 1997 Hamamatsu Photonics K. K.

FLAME SENSOR UV TRON® R2868

Figure 2: Angular Sensitivity (Directivity)

VERTICAL VIEWING

(Left fig.)

0˚

30˚ 30˚

60˚ 60˚

90˚

ANODE

CATHODE

100%

80
60
40
20

30˚ 30˚

60˚ 60˚

90˚

90˚

CATHODE

Figure 3: Dimensional Outline (Unit: mm) Figure 4: Recommended Operating Circuit

9.0±0.5

UV GLASS BULB

CATHODE 5 12

ANODE

ANODE

CATHODE

12 MAX.

23±1

32 MIN.

44 MAX.

(Side View)

18 MAX.

ANODE LEAD

CATHODE LEAD

4

8

LEAD: 0.7

TPT A0024EA

ANODE

8±1

0˚

100%

80

60
40
20

+

UV EMISSION
POINT

90˚

10MΩ 4.7 kΩ*

HORIZONTAL
VIEWING

@

(Right fig.)

ANODE

UV TRON R2868

i

CATHODE

10kΩ

325±25Vdc

220pF
500V

-

* Be sure to connect the 4.7 kΩ resistor within 2.5 cm

from the anode lead end of UV TRON.

• UV TRON Driving Circuit C3704 series (Option)

Hamamatsu also provide the driving circuit
C3704 series for R2868 operation.
C3704 series include a high voltage power
supply and a signal processing circuit in
printed circuit board, which allows to
operate R2868 easily as a flame sensor
with the low input voltage (DC 6 to 30 V)
only.
For the details, please refer to the
datasheet of C3704 series.

PULSE OUTPUT

1000pF

TPT B0010EA

TPT B0003EA

PRECAUTIONS FOR USE

• Ultraviolet Radiation

The UV TRON itself emits ultraviolet radiation in operation. When using two or more UV TRONs at the same time in close position, care should be
taken so that they do not optically interfere with each other.

• Vibration and Shock

The UV TRON is designed in accordance with the standards of MIL-STD-202F (Method 204D/0.06 inch or 10g, 10- 500Hz, 15 minutes, 1 cycle) and
MIL-STD-202F (Method 213B/100g, 11ms, Half-sine, 3 times). However, should a strong shock be sustained by the UV TRON (e.g. if dropped), the
glass bulb may crack or the internal electrode may be deformed, resulting in deterioration of electrical characteristics. So extreme care should be
taken in handling the tube.

• Polarity

Connect the UV TRON with correct polarity. Should it be connected with reverse polarity, operating errors may occur.

WARRANTY.

The UV TRON is covered by a warranty for a period of one year after delivery. The warranty is limited to replacement of any defective tube due to
defects traceable to the manufacturer.

HAMAMATSU PHOTONICS K.K., Electron Tube Center
314-5, Shimokanzo, Toyooka-village, Iwata-gun, Shizuoka-ken, 438-0193, Japan, Telephone: [phone], Fax: [phone],

U.S.A.:

Hamamatsu Corporation: 360 Foothill Road, Bridgewater, N.J. 08807-0910, U.S.A., Telephone: [phone], Fax: [phone]

Germany:

Hamamatsu Photonics Deutschland GmbH: Arzbergerstr. 10, D-82211 Herrsching am Ammersee, Germany, Telephone: [phone], Fax: [phone]

France:

Hamamatsu Photonics France S.A.R.L.: 8, Rue du Saule Trapu, Parc du Moulin de Massy, 91882 Massy Cedex, France, Telephone: [phone], Fax: [phone]

United Kingdom:
North Europe:
Italy:

Hamamatsu Photonics Italia S.R.L.: Via Della Moia, 1/E, 20020 Arese, (Milano), Italy, Telephone: [phone], Fax: [phone]

Hamamatsu Photonics UK Limited: Lough Point, 2 Gladbeck Way, Windmill Hill, Enfield, Middlesex EN2 7JA, United Kingdom, Telephone: [phone], Fax: [phone]

Hamamatsu Photonics Norden AB: Färögatan 7, S-164-40 Kista, Sweden, Telephone: [phone], Fax: [phone]

TPT 1008E01
MAR.1998 CR
Created in Japan