A capture hood, also known as a flow measuring hood, is an instrument used to measure volumetric air flows from supply or exhaust diffusers and grilles. Capture hoods make fast, repeatable measurements, making them excellent tools to verify air flow distribution, balance buildings, and pinpoint air system deficiencies. The Alnor family of Balometer Capture Hoods sets the standard for direct volume measurement. The Balometer hoods sample flow by catching air in the hood and channeling it past the measurement sensor in the base.

Most capture hoods, including the Alnor Balometer hoods, have lightweight fabric hoods in sizes to match common terminals, a meter readout device mounted on a sturdy flow base, and a measuring manifold mounted in the base. Alnor capture hoods use two different measurement technologies: thermal anemometers and mechanical swinging vane anemometers. The thermal anemometer sensors in the Electronic Balometer and the LoFlo Balometer Capture Hoods give excellent low-end sensitivity. The Standard Balometer and Balometer Jr. hoods use the mechanical swinging vane anemometers, which require no batteries or power source and are easy to use.

	Standard Balometer	LoFlo Balometer	Balometer Jr.	Electronic Balometer
meter (type)	Velometer (swinging vane)	unique LCD with analog scale (thermo-anemometer)	Velometer Jr. (swinging vane)	APM 150 meter with digital LCD (thermo-anemometer)
range	0-2000 cfm (0-3400 m3/hr, 0-950 l/s)	10-500 cfm (17-850 m3/hr, 4.7-236 l/s	0-1400 cfm (0-2400 m3/hr, 0-660 l/s)	50-2000 cfm (8.5-3400 m3/hr, 24-945 l/s)
other measurements	none	none	none	velocity, temperature or humidity with probe accessories
hood sizes*	2x2 standard; 2x4, 1x4, 1x5, 3x3 and more available	2x2 standard; 16x16 available	2x2 standard; 16x16 or shorty 2x2 available	2x2 standard; 2x4, 1x4, 1x5, 3x3 and more available
weight	9.8 lb (4.5 kg)	6.5 lb (3 kg)	6.9 lab (3.1 kg)	8.7 lb (4 kg)