Spectrex 20/20SH - Hydrogen Flame Detector - Manual (Page 13)

Spectrex Inc. - SharpEye TM Hydrogen (SH) Flame Detector Manual – TM 784600, Rev. A, May 2005
5
3. Performance
3.1 Detection Sensitivity
Detection sensitivity is the maximum distance at which the detector will reliably
detect a specific size of fire & typical type of fuel (standard fire).
Standard Fire:
Gases – define by a plume fire with 20” (0.5m) height and 8” (0.2m) width
or
Liquid - 1ft
2
(0.1m
2
) pan fire
Wind speed of 6.5 ft/sec (2 m/sec).
Sensitivity Ranges:
The detector has four user selectable sensitivity ranges. For each range there are
two response levels.
1. WARNING (Pre-alarm)
2. ALARM
The detection distance, for the WARNING level, is approximately 10% higher than
the ALARM distance.
Alarm response times for a “standard fire” at a specified range are shown
hereunder.
Table 1: Alarm Response Time Versus Range
Sensitivity 1 2 3 4
Range – ft (m) 16 (5) 33 (10) 66 (20) 100 (30)
Response Time (sec) 3 5 8 10
* These results refers to Hydrogen
For some typical ambient conditions the Zeta parameter as defined in NFPA 72 for
the detector is 0.005 (1/meter).
Note:
Zeta parameters may vary significantly with changes in temp, air pressure,
humidity, visibility conditions, etc.