Variable area Flowmeter

 

                                                            This type of flowmeter consists of a vertical tapered bore tube with a small bore at the lower end. A float is maintained in a vertical position within the tube by the flow forces acting on it. The pressure difference across the float is constant which means that the annular pass area around the float, and hence the float height, must vary depending on the flow. The tube can be metal to enable higher temperature and pressure to be used.

Advantages:

1. Linear output which results in higher turndown.

2. Simple and Robust

Disadvantages

a) Tube must be mounted upright

b) Moderate accuracy

c) Limited flowrates