Overhoff - Model FF-27 -Open Window Gas Proportional Monitor
The Model FF-27 is an open-window gas proportional monitor for measuring tritium (and C-14) surface contamination on flat surfaces. The FF-27 utilizes a large, rectangular windowless probe with 100cm2 sensitive area (6cm x 21.6cm) to quickly scan large areas, using poly tape to provide repeatable spacing from the surface as well smooth, scratch-free movement. The poly tape is easily cleaned, but may also be replaced if contaminated.
P-10 counting gas is used in the FF-27. It is non-combustible and can be used in any environment. Two lecture cylinders for P-10 gas are included with the instrument but are shipped empty due to shipping restrictions. P-10 gas use is minimized by careful design of the probe and by auto shut-off of gas flow when the ‘trigger’ on the probe handle is released. Gas flow is typically set at 800 cc/min providing a total of one hour’s use for the lecture bottle size, or longer with a larger cylinder. Typical counting efficiency is 70% 2pi of all tritium beta emissions escaping the surface. An optional “Model H Face Plate” can be used which will help improve counting efficiency when measuring objects that aren’t completely flat, such as hands, clothing, and equipment.
Includes PRS-7 scaler/counter/analyzer, which is a digital display pulse counter that covers a 6-decade range (1-100,000 CPS or other unit of choice). The PRS-7 is battery-powered, with an internal lithium cell and charger, and an external 12V AC power input. The PRS-7 has a preamplifier with a built-in single-channel analyzer with two adjustable thresholds so that pulses may be selected by their pulse height and cancel out other noise. It can also scale the counter display by a multiplier over a wide range, and the display can show both pulse rate and total pulse count, with a timer that will stop the counter after a preset interval. Includes an adjustable high voltage power supply with a range of 200-2500 Volts, audible/visible alarms, and RS-232 data output.
- Quickly measure large, flat areas for tritium (and C-14) surface contamination
- Sensitive Area: 100cm2 (6cm x 21.6cm)
- Sensitivity: 100 Bq/100cm2, 35 CPS above background
- Low gas consumption
- Portable, lightweight design with long battery life
- Audible and visible alarms, RS-232 data output
- MEASUREMENT RANGE : 6 decades, 1 to 100,000 CPS or other measurement unit of choice
- FLOWMETER : 10-1000 cc/min, needle valve control, factory set to 800cc/min
- BACKGROUND : 15 CPS
- DETECTOR : Windowless gas flow proportional counter
- SENSITIVE AREA : 100cm2
- SENSITIVITY : 100 Bq/100cm2, 35 CPS above background
- EFFICIENCY : 2pi 50% or more for C-14 and H3
- TIMER : Crystal controlled, 1 to 10,000 seconds, user settable
- DISPLAY MODES : Rate or Integrate
- ALARMS : Visible: orange light on front panel, Audible: piezoelectric sounder with volume control
- CALIBRATION : 4 range pots and 1 overall control, internal
- INDICATORS : Pilot light: Green indicator that the power is on
- Panel meter: Red Lion CUB5 LCD digital display
- Sonalert: Acoustic click for each pulse detected
- Alarm: Orange light indicating an alarm condition, if the alarm is enabled
- CONTROLS : Main Controls:
- On-Off, Show HV, HV Set, Alarm On or Mute
- Time Interval Controls:
- Auto or Singe Shot Mode, Start, Stop In auto mode, the measurement time is repeated continuously versus only once in single shot
- Energy Window Controls:
- Discriminator Level: 10-turn lockable dial adjusts discriminator threshold
- Window Level: 10-turn lockable dial adjusts window threshold
- Presets D, A, B: 3-position toggle switch to select one of 3 values for the discriminator threshold
- Position D is the 10-turn dial. A and B are alternative internal 10-turn potentiometers
- CONNECTORS : The connector for the probe is on the front panel, all other connectors are on the left side of case
- Power: 2.5mm round socket, 12V DC from an AC powered converter
- MHV: Coaxial cable connection to probe (MHV on instrument, BNC on probe end)
- HV Output: Separate HV connection that may be used instead of the HV on the MHV
- Alarm: 3-pin Philmore: Isolated connections for a remote alarm: common, NO, NC
- SIZE AND WEIGHT : Probe:
- 11” L x 2.25” W x 3.75” H including handle and gas shut-off switch, 0.57 kg (1 lb 4 oz.)
- Electronics with gas cylinder bracket:
- 10″ L x 4.1” W x 7″ H including handle, 2.5 kg (5 lbs) including batteries
- P-10 Gas lecture bottle: 0.6 kg (2 lbs 6 oz) when full (cylinders are shipped empty)
- Accessories included :
- 2 empty P-10 gas lecture bottles
- Cables and hoses
- Optional: Model H faceplate for measuring clothing, hands, and other uneven surfaces
- Model H faceplate allows better monitoring of hands, clothing, and equipment