Wind Speed Warning

In many industries knowledge of wind speed is essential for reasons of safety and productivity. For crane operators, civil engineers and mariners, it is often unsafe to work in high winds; on construction sites and landfills, understanding the behaviour of the wind is useful for pollution monitoring and odour control; and in the renewable energy sector wind resource assessments are required to assess the suitability of a particular site for the placement of wind turbines.

Anemometers are used to measure wind speed. Various types are available, which vary according to their measurement principle.

Cup anemometers are an industry standard for most types of wind measurement. The rotation of the cups generates an output signal that is directly proportional to the wind speed. They are reliable in a wide range of environments and can tolerate extremely high wind speeds with no compromise on accuracy.

Ultrasonic anemometers work by emitting acoustic resonances from one side of the unit to the other. There is change in wavelength according to the speed and direction of the passing wind. From this, an accurate wind speed measurement can be obtained. With no moving parts, ultrasonic anemometers are not subject to any physical constraints and can therefore detect the tiniest variation in the wind’s behaviour. They are lightweight, easy to deploy and require minimal maintenance.

Munro Instruments manufactures and supplies a range of cup and ultrasonic anemometers.  


IM124 Cup Anemometer

Built to British Meteorological Office specification, the Munro IM124 Cup Anemometer responds to wind conditions with extraordinary accuracy. Requiring no external source of electricity, it generates an AC output signal that is proportional to the wind speed. Wind speed measurements can be monitored quickly and easily using a Wind Speed Dial Indicator (IM124A) or a small OLED digital display. These can be sited remotely at key vantage points, such as in a crane cabin or at the base of a crane.

The IM124 Cup Anemometer can also be used with the IM613 Wind Speed Alarm Unit, which computes the average wind speed over a six-second period and will energise visual and audible alarm circuits to warn the workforce when critical levels have been exceeded.

Various data loggers are also compatible with the IM124.

IM159 Mechanical Handheld Cup Anemometer & IM161 Digital Handheld Anemometer

Handheld Anemometers provide a quick, easy and inexpensive method of obtaining wind speed measurements. They are compact, self-contained instruments, which are easily transportable.

The IM159 is built to British Meteorological Office specification and is suitable for a wide range of applications (military, aviation, oil & gas, fire safety, meteorology). It contains no electronic parts and is safe to use in explosive zones. It can be calibrated to read in knots, mph, or m/s.

The IM161 is a lightweight, battery-powered unit with a clear LCD display. It shows the actual fluctuating wind speed for a 12-15 second period and also the highest gust during the last 10 seconds of display. It will also indicate the average wind speed over the sampling period. It can be calibrated to read in knots, mph, m/s or km/h (this can be changed by the user at a later date).

Both are tested in our UKAS-accredited wind tunnel prior to despatch and can be supplied with a Certificate of Conformity if required.

2-Axis and 3-Axis Ultrasonic Anemometers

We supply a range of 2-Axis and 3-Axis Ultrasonic Anemometers. If necessary, these can be fitted with a heater to prevent accumulation of ice and snow in low temperatures. They are designed for use with SDI-12-compatible data loggers. Please enquire for further information.

For more information, please email or call +44 (0)20 8551 7000.


by Edmund Daley

IM146 & IM147 Wind Sensors

With over 150 years’ experience, Munro Instruments has developed considerable expertise in the field of meteorology. Early on, the company established a special interest in wind speed and direction, having assisted in the creation of the first ever Dines Pressure Tube Anemometer (1892). For over half a century, this was adopted as a standard instrument in observatories and meteorological offices around the world.

Later, in conjunction with the British Meteorological Office, a more compact wind measuring instrument was developed. The IM146, as it came to be known, was a highly innovative inline wind speed and direction sensor, comprising a cup anemometer and wind direction vane. Built to British Meteorological Office specifications, the instrument was quickly recognised as one of the most reliable and useful forms of anemometer, and it became an industry standard for professional weather observation and forecasting. Its accuracy, durability and ease-of-use meant that its range of applications extended well beyond that of pure meteorology, and it has since become one of the world’s most widely distributed anemometers.

Over half a century later, the IM146 continues to serve observatories, airports, offshore rigs, shipping terminals, harbours, power stations, cranes and bridges around the world (among others). After many decades of continuous use, thousands of IM146s remain in operation, providing users with accurate, up-to-the-minute wind speed and direction data. Its robust design and excellent versatility have been key to its longevity.

We continue to manufacture a near-identical version of the IM146. The newer IM147 Wind Speed & Direction Sensor offers the same functionality, accuracy and reliability as its predecessor, but uses a magnetic encoder, as opposed to a magslip, to relay wind direction data. The change was made in order to facilitate further development of the sensor.

The new IM147 can be used with the following analogue and digital displays:

  • Up to 6 x IM124A Wind Speed Dial Indicator
  • Up to 6 x IM125A Wind Direction Dial Indicator
  • Multiple IM617 Digital Wind Display Systems
  • The new Munro Data Acquisition System

The old IM120A Wind Direction Dial Indicator is no longer available. The IM125A, although identical to the IM120A in appearance and operation, may only be used with the IM147. The IM175 Duplex Roll Chart Recorder is also incompatible with any of our new wind sensors and is no longer manufactured. We do, however, continue to supply consumables (roll charts and recording pens), as well as certain spare parts. This excludes anything to do with the magslip or the voltometer.

In place of the IM175, we have developed a digital alternative. The new Munro Data Acquisition System performs multiple functions and can be used in place of both the IM175 and the IM617.

The newest iteration of the IM147 is telemetry-enabled. It incorporates a data logger for wireless transmission of wind measurements. It is designed for use with our accessible web-based software, ClimateCloud. This allows users to view wind speed and direction data anywhere in the world, anytime. Multiple sensors can be configured to a single account, allowing for the creation of a personalized weather network. Historical data is stored indefinitely, and alarms can be set up for when threshold measurements are breached.

Using an alternative power source (e.g. a solar panel) the IM147 can be deployed completely remotely, thereby dispensing with the need for cabling. It may be used as a stand-alone sensor or as part of an Automatic Weather Station (AWS). 2-axis and 3-axis Ultrasonic Anemometers are also available.

We are offering existing users of the IM146 the opportunity to retrofit their sensor, thereby making it compatible with the new features of the IM147. This is a simple process and involves replacing the magslip with a magnetic encoder. This can be carried out locally or at our factory in East London.

If you would like more information about any of our wind monitoring products, please email or call +44 (0) 20 8551 7000.

by Edmund Daley