A vintage Wilh.Lambrecht pitot tube airflow test meter.

*

I was lucky to find a very high quality measuring instrument in a wooden case at very low cost. It uses the pitot tube principle to measure airflow at the tip of the 'hockey stick' measuring wand.

It might have been used for measuring airflow in pipes or ventilation ducts.

The cylindrical meter reads in m/s. [Meters per second] The black handle can house two 'C' size batteries. These would light the small torch bulb which shines though a glass window in the meter base.Which would illuminate the measuring scale in poor conditions or even at night.

The bent main tube [wand?] is slightly damaged cosmetically. While the lower part of the wand is protected with a plastic coating. It is possible the damage was caused during normal use by an industrial ventilation engineer. The rest of the instrument is in fine condition as if from careful use.

Here is the active tip. The slot must be an air balancing vent. The orange cap has a hole in the centre of the nose to accept the airflow to be tested.

Something long and thin is missing from the slot provided in the case. Perhaps an alternative tube to fit inside the instrument? Or even a cleaning device?

The small vial has a label but has no contents. This vial is usually stored in a hole bored in one of the support bulkheads near the instrument's handle.



Here is the paper label found in the small glass vial.
My limited understanding of German suggests:
"Replacement nozzle 0,5 "
[A comma is used to define the decimal place on the Continent.]

Here is a close-up of the meter and one of its internal scales.

The main tube [wand] can be removed by unscrewing the central knurled ring.

The two large, knurled knobs on top the meter head rotate the four internal meter scales into view. The small, indicator is seen at rest in the meter window at the '0' position.

The scales are mounted on a rotatable white drum and are graduated as follows: 0-2.6 m/s. 0-8 m/s. 0-18 m/s. 0-50 m/s.

Which means that the device can measure over a range from roughly 0 - 110 mph. Since there are no visible moving parts one must assume that calibration between the ranges is made automatically by changes made internally.



Here is the connection between the test 'wand' and the top of the meter head. Note the perforations in each component and the very high quality of manufacture. Most of the visible components and fixing screws seem to be made of stainless steel or finely machined aluminium alloy.




Here is the small light bulb for illuminating the internal scales.

The base of the "torch" handle is provided with a standard tripod screw, mounting hole in a sturdy, knurled, screw in bush.

And here is the opal window through which the bulb shines.

Here I am testing the instrument in the open air on a windy day. A small electronic 'fan' anemometer is fixed near the head of the pitot tube for comparison. Both devices seem to agree but with varying reaction times to gusts.

This device cannot be easily used for measuring wind speed because it does not point continuously into the wind. Nor does it seem particularly suited to outdoor use.

Lambrecht meteo still manufacture a whole range of environmental measurement instruments at Göttingen, Germany.

http://www.lambrecht.net/de/home


Click on any image for an enlargement.

*