For all important diameters: the compressed air counter testo 6440

In four diameter sizes, the testo 6440 offers a compact design coupled with integrated high-performance technology, which provides all necessary signal outputs.
The built-in inflow and outflow pipes allow optimum accuracy.
The thermal, glass-coated ceramic sensor offers robustness at the same time as fastest reaction times.

Superior design from the sensor to the housing
In contrast to the penetration probes used by competitors, the sensor in the testo 6440 has a position in the pipe which is exactly known and always the same. With penetration probes, a tilt out of the vertical of 5° already leads to a measurement inaccuracy of 5%.
In the testo 6440, not only are the inflow and outflow pipes integrated, they also have completely even surfaces (i.e. no flange recesses etc.)
Many clever details in the design of testo 6440 ensure that the flow profile remains constant and that an optimum of accuracy can be achieved.

Defined interior diameter and volume flow adjustment for highest accuracy
Especially in small diameters, the exact knowledge of the interior diameter plays a deciding part in achieving accurate measurements of norm volume flow.
Commercially available penetration probes measure the flow velocity and calculate the volume flow by multiplication with the cross-section area. As shown in the illustration, even normed pipes can vary in interior diameter to such a degree that inaccuracies of up to 33% are possible.
The testo 6440 has an exactly known diameter – and is adjusted directly according to norm volume flow, and not flow velocity!