Model FF-27 Flat Feret Tritium Detector

Gas flow proportional counter

Tritium Surface Contamination Monitor

FF-26 and FF-27 Flat Feret Tritium Detectors by Technical Associates

The FF-27 Tritium Contamination Monitors are portable gas flow proportional counters, sensitive to betas of H-3. The windowless probes easily glide over flat surfaces on poly tape which provides some spacing from surface as well as easy scratch-free movement. The poly tape is easily cleaned but may also be replaced if contaminated. P-10 and P-5 counting gas utilized in these tritium monitors is non-combustible and can be used in any environment.

Gas use is minimized due to the efficient design of chamber and by an automatic shut-off valve when the ``trigger'' on probe handle is released. Typical counting efficiency is 50% 2 pi of all Tritium betas escaping the surface.  Results  were compared using an internal hemispherical 2 pi counter. Gas flow is normally set at 800 cc/min, giving a one hour use for lecture bottle or, of course, proportionally longer within larger cylinder. (See option below) Probe may also be used to monitor hands, clothing and equipment with included Model H face plate. Two lecture cylinders for P-10 gas are included with instrument. * cylinders are shipped empty when shipped.

The electronics include a power switch, high voltage pot and other controls are designed to prevent inadvertent change. The audio output of the high level alarm is controlled by a volume mute switch. Standard features include jack for AC adapter and serial output jack with optional USB adaptor. The system provides battery life up to one week and  weighs  only five pounds or 2.3 kg.

Model FF-27 is effective in rejection of other nuclides and integration capabilities.

Model FF-27 Specifications


0-10; 100; 1,000; 10,000 cts/sec (FF-26 and FF-27)
Flowmeter: 10-1000 cc/min. Needle valve control.
Background:    15 cps
Open range switch, battery check, flow gas control, sound volume
Hidden high voltage bias supply for detector: Input sensitivity high
voltage control.
Sound Volume control
Calibration: four range pots and one overall control. Internal.
Detection Area: 100 cm2
Sensitivity: 100 Bq/100 cm2, 35 cts/sec above background
Battery: 2 nine volt,  300 hours normal operating life.
Weight and Dimensions:

Weight: 0.57 Kg (1b. 4 02.)
Dimensions: 11 in L x 2-1/4 in W x 3-3/4 in H including Handle & Gas Shut Off Switch
PRS-7 Electronics with Gas Cylinder Bracket:
Dimensions: 10 in.  L x 4.1 in. W x7 in. H (25 cm L x 10.5 cm W x 18 cm H)
Weight: 2.5kg (5lbs) including batteries.
Options: Alarm Relay
Detector: FF-26: 20 cm2 Sensitive Area
Larger Gas Cylinder: (DOT 3AA2015) On two wheel dolly.
Model H Face Plate: Hands, Clothing, Equipment Probe