Measuring heat index is not enough to keep you safe in the heat

You have probably heard of the term ‘heat index’ used when a temperature ‘feels’ different than what your weather app is showing you. Heat index simply takes into account humidity to the temperature in shaded areas. This means that if you work in direct sunlight you can not be sure that you are safe.

In order to determine the true real feel of the weather, a technology known as Wet Globe Bulb Thermometers provide precise readings on when being exposed to the heat is too dangerous. Heat stress trackers can be used in a vast range of industries such as agriculture, construction, military and facility management.

The Kestrel 5400 not only provides heat index readings, but uses Wet Globe Bulb Thermometer (WBGT) to provide an indication on heat stress in direct sunlight and therefore provides a fantastic solution to occupational heat tracking needs. WBGT is based on an equation that uses a combination of environmental elements to calculate the reading including humidity, wind, sun angle and cloud cover.

Industries such as sport, military, construction and agriculture are prime examples of professions that require WBGT technology, as much of their work is done outside in direct sunlight. The Kestrel 5400 is sold at RPR beginning at £408.29 (ex. VAT) for the non-LiNK version and is the leading choice in heat stress management.

The Kestrel 5400 displays a Thermal Work Limit (TWL) which measures real human heat stress. TWL is measured in terms of the heat energy a person can dissipate from their surface area in Watts per square meter (w/m2) and provides solutions already to US organisations such as National Athletic Trainers Association (NATA), National Collegiate Athletic Association (NCAA) and the Women’s Tennis Association (WTA).

For further accuracy, the Kestrel 5400 allows you to change 4 settings to get the most out of your meter. These settings include position of the body, surface area of the body, intrinsic clothing insulation factor, and vapor permeation factor (AKA how much of your body is allowed to breathe).

Made in the USA, the Kestrel 5000 series provides data on a full suite of weather paaramaters including dew point, density altitude, wind chill, air, water, and snow temperature and wind speed. The Kestrel 5400 is waterproof, has an easy-to-read backlit display and can be linked to a data logger or the LiNK bluetooth app to provide easy-to-read graphical data that can be stored and customised.

A fresh batch of Kestrel 5400’s have just hit our store. If you are interested in how heat stress trackers can be used in your workplace, give us a call at +44 (0) 1590 641223 or email the sales team at

The Best Kestrel Accessories This Summer

Upgrade your Kestrel 1000 – 5000 series with these accessories to get the most out of your meter.

Vane Mount and Case:

Turn your Kestrel device into a complete weather station with a vane mount and case. Beginning at £54.95 inc. VAT for the 1000-3000 series, the vane mount and case securely mount any Kestrel to a tripod, giving you more options on how you use your Kestrel meter. Your meter can be stored in the vane mount pouch, making it the most portable weather station in the world.

Mini tripod and clamp:

LiNK iOS app

Built for the K5000 series, the mini tripod is the perfect option for ballistics when shooting from range stand. Sturdy and lightweight, the tripod is extremely portable and weather resistant, ensuring you can take that perfect shot wherever you go. Featuring three adjustable legs. non-slip vinyl feet, and a tilt/rotate U ball, you can be certain that even on the most uneven of surfaces that you will get accurate readings. Price: £36.95 inc. VAT

LiNK App:

Does your Kestrel have Bluetooth? Download the LiNK iOS/Android app to get remote mobile device viewing of real-time readings from your Kestrel 5000 Series Meter or DROP data logger. You can keep historical data stored on your device and view graphs to help you analyse your shots. The app also allows you to set alerts in certain weather conditions, including emails to your device, ensuring you only shoot when conditions are appropriate. Price: FREE

HST Molle Carry Case:

HST Carry Case

Pair your Kestrel 5400 Heat Stress Tracker with a heavy duty Cordura Carry Case – the ultimate protection for your Kestrel. Featuring a rugged outer shell and zip feature, this carry-case allows you to take your K5400 into tough conditions all over the world. Made of 500-denier Cordura nylon and 200-denier Kevlar, this case is extremely resistant to abrasion and damage in the harshest of environments. Price: £69.95 inc. VAT

All you need to know about Britain’s favourite yacht race

Attracting on average 15,000 sailors and 1,400 boats, the Round the Island Race organised by the Island Sailing Club is the fourth largest participation sporting event in the UK behind the London Marathon, Great North, and South runs.

Competitors from around the world race around the Isle of Wight, covering 50 nautical miles starting from the famous Royal Yacht Squadron line in Cowes. Racers loop around The Needles, St Catherine’s Point and Bembridge Ledge buoy on their way back into the Solent and the finish line at Cowes.

The first Round the Island Race took place in 1931 with 25 entries after Major Cyril Windeler suggested a handicap race which could cater for smaller boats – a quiet joke at the expense of the Royal Yacht Squadron who had stated that their members must own a yacht of at least 30 tons! The record number of entries was set in 2008 with 1,875 and the course record was set by Lloyd Thornburg’s Phaedo^3 in a time of 2 hours 22 minutes and 23 seconds on Concise 10 in 2017.

There are almost 200 prizes available over the course of the weekend for boats of every shape and size, with individual and team trophies on the line including the main prize – the Gold Roman Bowl. The race is a unique opportunity to watch amateur sailors go up against the professionals (including Dame Ellen MacArthur!) and has seen Olympians such as Ben Ainsely come out victorious. The event is also set to raise thousands for the Ellen MacArthur Cancer Trust.

Ben Ainsley and team celebrating their win in 2013.
Photo: Peta Stuart-Hunt

Online services such as WeatherFile provide competitors with live data on a range of parameters such as wind speed and direction, temperature, precipitation, and pressure so that they can manoeuvre the course appropriately. With perfectly placed weather stations at Hurst Castle , Yarmouth Pier, Lymington Starting Platform, and Stokes Bay Sailing Club, racers can fine tune their strategy with ease. There will also be a weather briefing at 5pm on Friday by meteorologist Simon Rowell.

WeatherFile Data

The racing begins at 8am on the 25th of June. Entries remain open until June 22nd. For tips on viewing and more information, visit

Good luck to all competing!

5 tips for managing heat stress in the workplace

With temperatures rising as we head in to the summer months, it is becoming increasingly important to manage heat stress in the workplace. Employers, managers, and health and safety personnel are responsible for tracking heat and other weather parameters to ensure the wellbeing of their staff.

Heat stress is particularly prominent in industries such as construction, agriculture, fire-fighting, emergency services, military, sport and the environment. The CDC describes how “workers who are exposed to extreme heat or work in hot environments may be at risk of heat stress. Exposure to extreme heat can result in occupational illnesses and injuries. Heat stress can result in heat stroke, heat exhaustion, heat cramps, or heat rashes”. Here are 5 ways you can keep your employees safe:

Monitor working conditions

A variety of heat stress trackers are available, including the Kestrel 5400.The Kestrel 5400 is a highly accurate, handheld device that monitors heat, humidity, wind speed and direction, pressure and altitude. It provides a heat stress index making it the ideal product when determining safe working conditions, setting rest breaks and maximising personnel performance. The WBGT data does not require water making it incredibly easy to use.

By adding Bluetooth connection (LiNK) to your device, you can record live data and send it to your device in real time. The free Kestrel LiNK App for iOS/Android puts crucial information at your fingertips with remote mobile device viewing of real-time readings from your Kestrel 5000 Series Meter.

The Kestrel 5400 is the ultimate solution for those looking for an easy, affordable setup and want the option of alerts at critical thresholds. It trumps the Kestrel 3000 by providing data on crosswinds, pressure, altitude and many other unique parameters. The Kestrel 5400 is IN STOCK at RPR now.

Sign up to the newsletter to hear more about uses of the Kestrel 5400 next week.

Learn more about the Kestrel 5400 here

Provide training resources

As well as tracking heat, employers can provide training resources so that their staff know when it is safe or unsafe to work. Employers can provide information on signs of heat stress, how to administer first aid and appropriate attire for working in tough conditions.


Training resources are a good place to start, but sometimes the heat can still be a shock to the system. It’s important for employers to learn the significant benefits of acclimatising to warm conditions. Acclimatising provides a physiological advantage in warmer conditions as employees become used to the heat and the way it affects them. The CDC recommends new starters should spend 20% of their first day in the heat, followed by no more than a 20% increase each day. Employees should be supervised, particularly if they are not physically fit.

Hydrate, hydrate, hydrate

It goes without saying that water is your best friend in the heat. We all know that 2 litres of water a day is the standard when it comes to hydration – but experts agree that 1 cup of water every 15-20 minutes is more appropriate for warm conditions, with the need for electrolytes if working for greater than 2 hours. In addition to this, water should be potable (15 degrees or less) and made accessible to the work area.

Take a break

Don’t be afraid to take a rest from work. Long exposure in the heat is both dangerous and draining. You are more likely to be productive with regular breaks out of the sun. Find shade and take some time to hydrate. Employers should be proactive in allowing rest breaks and should assign more frequent breaks to those who are unfit or not yet acclimatised.

Kate Lobanova – Gritr Outdoors

For more information on the Kestrel 5400 view our website or call our sales team at +44 (0) 1590 641223.

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What’s new at RPR?

Updated Products

We have a wide range of new products in stock. Visit our website or get in contact with our sales team to learn more.

  • The WeatherFile WF1 system is a unique internet connected weather station solution allowing users to select from a wide range of high-quality meteorological sensors and methods of connectivity.
  • The Kestrel 5700X offers the same accuracy and reliability as the industry gold standard Kestrel 5700 Elite, with increased performance power to deliver faster firing solutions in the field for multiple extreme long-range targets. With an upgraded processor that is more powerful and faster than the K5700 Elite, the K5700X provides quicker targeting data for extreme long-range targets

More information will be provided in the coming weeks so please subscribe to our newsletter for further updates.

Exhibition Schedule

We are excited to announce that we will be attending three exhibitions in the next few months. Come along and chat to our sales team to find out more about our products.

  • Bisley Festival of Shooting – 13th-14th August 2022, Lord Roberts Centre and Century Range at the Bisley Camp, Woking 
  • Emergency Services Show – 21st-22nd September 2022, NEC Birmingham
  • Meteorological Technology World Expo – 11th-13th October 2022, Paris, France

New Staff

We have added 3 experienced members of staff to our team. You can contact them by calling: +44 (0) 1590 641223

  • Roxana – Finance and Sales Admin
  • Jaymee – Sales and Marketing
  • Andy – Web Developer and IT


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Enjoy your week!


Manage Workplace Heat Stress with the Kestrel 5400 Heat Stress Tracker

In many jobs the risk of heat stress increases during the hot summer months (such as the ones we are experiencing now), it is important you are aware of how to work safely in heat, the factors that can lead to heat stress, and how to reduce the risk of it occurring.

Heat stress occurs when the body’s means of controlling its internal temperature starts to fail. Air temperature, work rate, humidity and work clothing are all factors which can cause heat stress.

The body reacts to heat by increasing the blood flow to the skin’s surface and by sweating. This cools the body as heat is carried to the surface from within by the increased blood flow and sweat evaporates. Heat can also be lost by radiation and convection from the body’s surface.

Some workers are more at risk of experiencing heat stress:

  • Those wearing heavy PPC clothing which can restrict sweat evaporation
  • High workplace humidity
  • Workers who with a high work rate, road workers for example
  • Exposed workers with no shade or those working in areas with high levels of reflective heat from surrounding surfaces

The above can lead to restricted sweat evaporation, an individual’s deep body temperature rising, the body may then respond by increasing sweat production leading to potential dehydration, increased heart rate. Eventually the body will struggle to control the situation leading to a potentially dangerous heat stress situation.

It is therefore important to have an effective environmental monitoring solution so workers and employees can keep track of the key environmental parameters that lead to heat stress.

The Kestrel 5400 Heat Stress Tracker does just that measuring all the relevant parameters including Wet Bulb Globe Temperature (WGBT), Relative Humidity, Heat Stress Index, and delivery Thermal Work Limit measurements.

You can set thresholds and will be made instantly aware if they are exceeded by a loud buzzer, bright LED beacon and on-screen warnings enabling you to manage dangerous conditions quickly and with accurate information at hand. Uniquely the Kestrel 5400 is also a complete weather station measuring wind speed, maximum wind gusts, temperature, humidity, pressure, wind chill, density altitude and more, making the Kestrel 5400 the ideal product when determining safe working conditions, setting rest breaks, and maximising personnel performance.

All data can be stored and downloaded for records if required.

To order, or for additional information on the Kestrel 5400 Heat Stress Tracker, please visit email or call the technical sales team on +44 (0) 1590 641223

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Richard Paul Russell Ltd Continue Growth in Temporary Structures Market

Richard Paul Russell Ltd have over 20 years of experience in the wind and weather monitoring market and have been supplying many customers within the events and temporary structure market including Victorious Festival, StageCo and Baconinflate.

Product solutions have expanded and split into two main areas, handheld and fixed solutions. Handheld devices offer a simple and cost-effective way of measuring wind speed at a local level.

Fixed solutions allow the sensor to be located above the structure roofline in a clear wind path, log data continuously and allow a live view of data from any location using any internet connected device, data can be downloaded into Excel format for records.

A short overview of the most popular options is below:

Handheld Solutions

  • Kestrel 1000 – Pure instant wind speed reading with average for duration you hold it for. This product does not log data and would require the user to manually take note of the wind speed conditions
  • Kestrel 5000 Weather Station – Allows for all weather parameters to be measured and logged on the unit with a Bluetooth link to transfer data wirelessly to PC, laptop, smartphone etc as required
  • Pricing starts from £58.29 to £324.96 ex VAT

WeatherFile Cloud Connected

  • Logs data continuously and stores locally
  • In addition, transfers data over local GSM Cellular Mobile network, WiFi Network or LAN (ethernet cable) to WeatherFile
  • WeatherFile can be viewed from any location with any internet connected device
  • Email alerts can be set to warn if wind speeds exceed certain set parameters
  • Data can be downloaded free of charge without limitations for any time period in .CSV (excel) format
  • Data never lost as stored locally on SD card and also remotely within the WeatherFile cloud solution
  • Complete systems from around £1270 ex VAT
  • This system can also be hired

Richard Paul Russell Ltd systems meet the Institution of Structural Engineers guidance on temporary demountable structures, procurement, design and use and they are available to advise on product selection, installation and monitoring, working with clients in developing bespoke solutions if required.

You can contact our technical team by email or call +44 (0)1590 641223


Maximise effectiveness, minimise waste, and avoid harmful off-target crop spray drift with the new portable, connected 3550AG meter for pesticide spraying applications — the latest from the trusted line of Kestrel® environmental handheld weather monitoring devices. Rugged, waterproof, affordable, and easy-to-use, the 3550AG comes equipped with Bluetooth® connectivity for instant wireless data capture to a mobile device and shareable reports with the free Kestrel® App.

Richard Paul Russell Ltd, announces the release of the Kestrel 3550AG Agricultural Weather Meter. Precise on-site wind, temperature and humidity awareness is the key to avoiding spray drift liability and maximising application results. There is no easier and more affordable tool for this job than the portable, rugged, handheld Kestrel 3550AG. With just your phone and this Bluetooth-enabled weather meter, users can capture critical weather data throughout their workday and anywhere on their operation.

Farmers put themselves and their business at risk every time they spray a field without measuring and documenting the wind speed and environmental conditions.  Off-target pesticide drift can not only cause damage to nearby vulnerable crops but also pose a serious threat to people, livestock, wildlife, and the surrounding community. No matter the size of the operation, effective herbicide and pesticide application is critical to financial success. The Kestrel 3550AG (£189.95 inc VAT) fits in a pocket yet is equipped with factory-calibrated sensors to measure wind speed and direction, relative humidity, and more. Dew Point and Delta T readouts help the applicator avoid wasteful spray evaporation in excessively dry conditions. Plus, carrying a Kestrel in the spray equipment ensures readings can be taken exactly as recommended – at the field location and at the height of the spray boom. Readings from apps or weather reports gather weather data miles away from the farm location and at the required 30 foot height are in no way correct for on-site conditions.


  • Minimum/maximum/average readings
  • Snapshot mode captures and saves all live measurements
  • Bluetooth® Mobile Device Connectivity and Free Kestrel iOS and Android Apps
  • Simple 3-button operation
  • High contrast, sunlight readable LCD display with backlight
  • Rugged design— IP67 waterproof & MIL-STD-810G drop-tested
  • Effortless Record Keeping & Data Export Capabilities

As regulations surrounding drift management get tighter and media and public attention continues to increase, the stakes are higher than ever for applicators and farmers when it comes to accountability. It is imperative to measure and document spray conditions at the time of application to be ready to defend against a claim of spray drift damage . The Kestrel 3550AG with Bluetooth connectivity makes it easy to instantly capture and log accurate weather data with just one-click. The free iOS or Android Kestrel App allows the user to view, manage, save, and export their captured data with just their phone for instant access and convenient reporting on spraying conditions.

To order, or for additional information on the Kestrel 3550AG Spraying Weather Meter, please visit email or call the technical sales team on +44 (0) 1590 641223


Capable and connected for continuous monitoring, and shareable reports, the 3550FW delivers the same rugged reliability and accurate performance that wildfire firefighters have trusted for years while enabling them to capture and share critical fire weather data far more quickly and easily.

Richard Paul Russell Ltd, announces the release of the Kestrel® 3550FW Fire Weather Meter. Kestrel’s newest and most affordable fire weather meter is now more capable and connected. The 3550FW has all the original features and comprehensive weather monitoring capabilities of the benchmark Kestrel 3000 plus a digital compass for wind direction, Kestrel Bluetooth® wireless connectivity for remote viewing and instantaneous sharing of weather data from a mobile device, and an extra coin cell battery to ensure you won’t lose power in the field when you need it most.

The Kestrel 3550FW (£189.95 inc VAT) keeps your team connected with shareable and exportable condition reports with GPS location via text and email right from the free Kestrel App. Even when you are on the move, you can wirelessly log and retrieve data for real-time monitoring and reporting.

Unlike a traditional Weather Belt Kit, the 3550FW captures readings of ten critical weather measurements near instantly, with less reliance on user technique and instrument maintenance. Barometric pressure, altitude, dew point, heat stress index, relative humidity, temperature, wind speed and direction, wind chill and wet bulb are all measured by the Kestrel 3550FW as soon as the unit is removed from its protective cover and held into the air. Ready to be tossed in your pack, the Kestrel 3550FW is IP67 waterproof and Mil-SPEC-810G drop tested.

To order, or for additional information on the Kestrel 3550FW, please visit email or call the technical sales team on +44 (0) 1590 641223

COVID-19 Statement

At present, in line with the governments guidelines we are remaining open. We would ask only those who are in good health or not in the ‘high risk category’ to visit any of our facilities.

As well as our normal cleaning procedures we have taken extra measures in order to try and prevent any contamination or spread on COVID-19.
We have also increased the frequency of our cleaning regime at all our facilities.

Below are the links to the government guidelines regarding COVID-19.

Public Health England (PHE) recommends that the following general cold and flu precautions are taken to help prevent people from catching and spreading COVID-19:
• Cover your mouth and nose with a tissue or your sleeve (not your hands) when you cough or sneeze. See Catch it, Bin it, Kill it
• Put used tissues in the bin straight away
• Wash your hands with soap and water often – use hand sanitiser gel if soap and water are not available. See hand washing guidance
• Try to avoid close contact with people who are unwell
• Clean and disinfect frequently touched objects and surfaces
• Do not touch your eyes, nose or mouth if your hands are not clean

Please keep an eye on our website and social media channels for updates as the situation evolves.
At present our production facility and online shop are business as usual, subject to product availability and delivery. So please feel free to place orders and shop online!
Link below on the guidance on social distancing for everyone in the UK