## What is rangeability on a flowmeter?

Turndown ratio is also commonly referred to as rangeability. It indicates the range in which a flow meter or controller can accurately measure the fluid. In other words, it’s simply the high end of a measurement range compared to the low end, expressed in a ratio and is calculated using a simple formula.

What are the main limitations of rotameter?

• It is difficult to handle the glass tube type.
• It must be mounted vertically.
• It is not suitable for pulsating services.
• Generally it is limited to small pipe services.
• It is limited to low temperatures.
• Accuracy is = ± 1/2 to 10%.
• It requires in-line mounting.

What are the applications of rotameter?

The applications of rotameter include the following.

• Rotameters are used in different industries.
• These are used where there is a quality air supply is required.
• This is used where low pressure is necessary.
• Used in laboratories.
• Process and oil industries.
• Used in the medical field for measurement of oxygen flow rate.

### How is rotameter measured?

The metering tube in a rotameter is installed vertically (Figure 2-15) and the small end is at the bottom. The fluid that is going to be measured enters at the bottom of the tube, passes upward around the float, and exits the top. If there is no flow, then the float stays at the bottom.

What is instrument rangeability?

Turndown ratio is often also referred to as the rangeability of an instrument. It is defined as the ratio of the maximum capacity of measurement to the minimum requirement for measurement. It is expressed as a multiplication factor from the lowest range to the highest range.

What is rangeability and turndown?

Rangeability defined as the ratio of maximum controllable flow to the minimum controllable flow that a device designed to. So this is a theoretical value before a device installed. The turndown ratio gives the width of the operational range of a device/valve. It is not required to handle the maximum possible flow.

That is, the venturi meter must be driven by a straight tube that has no connections or misalignments to avoid turbulence in the flow, for satisfactory operation. It can not be used in pipes of less than 7.5 cm in diameter. Maintenance is not easy. It can not be modified to measure the pressure beyond a maximum speed.

• The cost of rotameter is low.
• It provides linear scale.
• It has good accuracy for low and medium flow rates.
• The pressure loss is nearly constant and small.
• Usability for corrosive fluid.

What are the applications of pitot tube?

Pitot tubes are used in anemometers to measure airspeed in wind tunnels and aboard aircraft in flight; they are also used to measure the flow of liquids (see flow meter).

### What is measured using Venturi meter?

Venturimeter is a device used to measure the rate of flow of fluid flowing through a pipe. Venturimeter is a device which is used for measuring the rate of flow of fluid flowing through a pipe.

How accurate are rotameters?

The ball type of flowmeter has a ±5% accuracy rating, and the rotameter has a ±2% accuracy rating.

How do you calculate rangeability?

The minimum flow is defined as the ‘minimum flow at which design characteristics are maintained’. For example, a double-seated valve with a leakage of 2% in the closed position, but otherwise conforming fully to its specification, would have a rangeability of R = 100%/2% = 50.