DESCRIPTION

Technical Description

Measuring pressure is important in the engineering industry, e.g. in plant, turbomachine and aircraft construction and in process engineering. Other fundamental factors such as flow rate or flow velocity can also be determined based on a pressure measurement.

The WL 203 experimental unit enables the user to measure the pressure with two different measuring methods: directly by measuring the length of a liquid column (U-tube manometer, inclined tube manometer) and indirectly by measuring the change of shape of a Bourdon tube (Bourdon tube pressure gauge).

In a U-tube manometer, the pressure causes the liquid column to move. The pressure difference is read directly from a scale and is the measure for the applied pressure. In inclined tube manometers, one leg points diagonally up. A small height difference therefore changes the length of the liquid column significantly.

The principle of the Bourdon tube pressure gauge is based on the change in cross-section of the bent Bourdon tube under pressure.  This change in cross-section leads to an expansion of the Bourdon tube diameter. A Bourdon tube pressure gauge is therefore an indirectly acting pressure gauge where the pressure differential is indicated via a transmission gearing and a pointer.

In experiments, pressures in the millibar range are generated with a plastic syringe and displayed on the manometers. The experimental unit is equipped with two Bourdon tube pressure gauges for measuring positive and negative pressure. The U-tube manometer, inclined tube manometer and Bourdon tube pressure gauges at the experimental unit can be combined using tubes. A calibration device (HM 150.02), which is included in the scope of delivery, enables calibration of an additional Bourdon tube pressure gauge using a weight-loaded piston manometer.

The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

Learning Objectives / Experiments

- familiarisation with 2 different measuring methods:
  * direct method with U-tube manometer and inclined tube manometer
  * indirect method with Bourdon tube pressure gauge
- principle of a Bourdon tube pressure gauge

in conjunction with the HM 150.02 calibration device included in the scope of delivery
- calibrating mechanical manometers