Spectrex-The BFM-2500

The BFM-2500
5-4000 cc/min

A portable electronic bubble flow meter for gases.

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Features

Flow range equals 5-4000 cc/minute
Instant measurement of flow for vacuum port calibration
Instant measurement of flow for pressure port calibration
Direct readout in liters or ccs per minute
Accuracy is ±3% of reading with National Bureau of Standards (NBS) traceability over entire flow range
Standard 9-volt alkaline battery provides 50 hours of continuous use; automatic "power-off" feature and low power electronics
LCD display (½" high) is autoranging and easy to read
Performs self testing, displays "fault" and "low battery" conditions
Compact size: 5" x 6" x 9" Weight: 2.5 lb.
Rugged, stainless steel housing with chemical resistant overlay Soap film solution and operating manual provided

A portable electronic bubble flow meter

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A soap bubble passes up the column of a precision-bore, constant diameter glass tube at a speed dependent on the flow rate of the source to be calibrated. This speed is monitored by two light sources and infrared detectors spaced along the tube. The time base is a precision, 6± .005% MHz quartz crystal.

The micro circuit in the flow meter automatically monitors the speed of the bubble, computes flow rate in liters/cc per minute and instantly displays this flow with the liquid crystal readout.

The Soap Bubble technique provides an absolute, volumetric method of flow measurement and is directly traceable to a National Bureau of Standards (NBS) calibrated standard. Thus it is possible to individually calibrate each BFM-2 500 to high precision and NBS traceability.

Both pressure and vacuum sources can be monitored, and the flow obstruction generated by the system is negligible. This is in sharp contrast to that of mass flow meters and rotometers.

Gas flow calibration in the field for:
Industrial Hygiene — personal air samplers; flow-through charcoal tubes, midget impingers, Draeger tubes, adsorber tubes, and gravimetric filters.
Asbestos samplers
All gases in chromatography
Leak detection
Laboratory gas analyzers
Industrial gas flow devices
Diffusion testing of filters in pharmaceutics, semiconductor manufacturing, and electronics research.
Dimensions: 5" x 6" x 8.75"
Weight: 2.5 lb (1140 g)
Time base: 6 MHz ± .0005%

Read-out: Liquid crystal Accuracy ±3% of reading Temperature range 0° C - 70°C Power source: 9-volt DC alkaline battery for 50 hours of continuous use