4
Arson Scanner Hydrocarbons
and Accelerant Detector
MODEL 950-ASH
The Model 950-ASH Arson Scanner Hydrocarbon and
Accelerant Detector is a precision instrument designed
specifi cally for detecting trace levels of hydrocarbons
and accelerants.
Model 950-ASH is optimized for detecting hydrocar-
bons or accelerants that may be present at suspect
arson fi res. Model 950-ASH functions as an excellent
general purpose discovery instrument for fi eld survey
such as: searching landfi lls for methane outgassing,
detection of leaking underground storage tanks, or
simply as a general purpose gas leak detector.
Additionally, Model 950-ASH employs an array of
illuminating ultraviolet and white LEDs which further
assist the investigator in locating accelerants or other
evidence in situations where detection in low visibility
environments becomes diffi
cult. Other benefi cial
features include a Mute function to silence the audible
tones for discreet investigation and a Purge feature for
rapid Sensor recovery.
PRINCIPLE of OPERATION
Model 950-ASH Sensor is a solid-state semiconductor
type whose resistance changes in the presence of
hydrocarbon or accelerant vapors. This change in
resistance is sensed by the signal processing electron-
ics and is displayed as an audio and visual rate signal
that is proportional to the relative concentrations of
hydrocarbons/accelerants present. The Sensor is
heated while the detector is in use to provide stable,
consistent operation. The sensing element is housed in
a thimble-like structure of a double layer of very fi ne
stainless steel assuring complete operating safety as
well as providing mechanical protection.
OPERATION
POWER ON:
Power the Model 950-ASH ON by
rotating the Power On/Off Detection Range Control
clockwise until a click sound is heard. The blue Power
Indicator LED will begin to fl ash, indicating the 950-
ASH is in the warmup and Sensor stabilization cycle.
After approximately 90-120 seconds, the blue POWER
Indicator LED stops fl ashing and glows blue to indicate
the Sensor has reached operating temperature and the
instrument is ready for use. During the warmup cycle,
you may observe a defl ection of the needle and rapid
fl ashing of red LEDs on the Analog Meter Display. This
action is normal and will cease as the detector
gradually attains operating temperature. NOTE: The
Sensor may not detect the presence of hydrocarbons
or accelerants while in the warmup cycle.
The ultraviolet and white LED Arrays will function
during the warmup cycle.
SETTING the SENSITIVITY
SETTING the SENSITIVITY:
After the 950-ASH has com-
pleted the warmup cycle and is in the READY mode, it is
time to set the RANGE and sensitivity. Toggle the Range
Switch to the HIGH position.
HIGH RANGE allows for the detection of trace levels of
hydrocarbons or accelerants.
Rotate the Detection Range Control clockwise until
the needle on the Analog Meter Display defl ects clock-
wise and the red Hydrocarbon/Accelerant Detection
LEDs begin to fl ash. If the Mute switch is OFF, you will
observe audio tones in synchronism with the red LEDs.
To silence the audio tones, switch the Mute control to
ON. Next, slowly rotate the Detection Range Control
slightly counter clockwise until you no longer observe
the red fl ashing LEDs, the audible tones cease and the
needle on the Analog Meter Display falls to the 0, 1, or
2 region of the display.
The Model 950-ASH is now ready to scan for hydrocar-
bons/accelerants.
NOTE:
LOW RANGE is used when an area of concern has
high concentrations of hydrocarbons. In LOW RANGE,
the sensitivity is reduced to assist in pinpointing hydro-
carbon / accelerant source.
DETECTING HYDROCARBONS
or ACCELERANTS
To detect the presence of hydrocarbons/accelerants,
scan the suspect material or area of concern at an
angle of approximately 45° while holding the Sensor
end of the Telescoping Sensor Probe approximately
½” to 1” from the area to be surveyed. Scan very slow-
ly to provide suffi
cient time for vapor to penetrate the
Sensor.
NOTE:
The time required for a hydrocarbon or
accelerant to change from liquid to vapor and diff use
into the Sensor is dependent upon environmental
factors such as temperature, humidity, wind velocity
and the type of hydrocarbon/accelerant. It is important
to take your time and be patient.
NOTE: to silence the 950-ASH for discreet investigation,
switch the Mute control to the ON position.
