Tag Archives: Temperature

White Paper – Save time and money with modern monitoring and calibration

The text below is taken from a Rotronic White Paper available here in full.

Companies across many industries needing to perform regular monitoring and calibration have never faced a more challenging environment. Stricter compliance requirements mean companies are under greater pressure to deliver accurate and reliable data, whilst internal budget restrictions demand the most cost effective and efficient solutions.

Can modern measurement &  calibration techniques help your business operations?

It is well known that accurate measurements reduce energy use and improve product consistency. Instrument users, calibration laboratories and manufacturers are constantly looking for smarter ways of operating and are responding with innovations that are transforming the measurement and calibration industry.

New ways of working

Industrial environments are now more automated and interconnected than ever before and companies need to ensure that their infrastructure and processes have the ability to respond and adapt to industry changes. With the introduction of newer, more complex instrumentation, organisations can often be slow to recognise the additional business benefits that can be achieved by replacing a traditional method that (offers a short term result) with a more modern method (that delivers a longer term sustainable solution). Implementing a new approach can also help re-position the calibration process from being viewed simply as a cost to business to one that helps deliver improved process and energy efficiencies with a return on investment.

Industry advancements

Historically, in-situ calibration has been the standard approach; however, advances in technology means that there is now a viable alternative whilst still maintaining the growing demand for on-site services. With the market moving away from analogue to digital signal processing, interchangeable digital sensors are proving to be a more practical solution for both large and small organisations alike. As businesses look for greater automation and productivity, modern interchangeable digital sensors are allowing calibration to be achieved much more quickly without the costly implications of operational downtime and on-site maintenance.


Why calibrate? – The only way to confirm performance
In unsettled economic times it can be tempting to simply extend the intervals between calibration cycles or to forgo calibration altogether. However, neglecting system maintenance and calibration will result in reduced performance and a loss of measurement confidence, ultimately leading to a failure to meet compliance standards. Measurement drift over time negatively impacts on processes and quality. Regular, accredited calibration demonstrates compliance, but equally importantly, sends a message to customers that quality is taken seriously and that they can be confident in both the process and the final product.
What is your route to traceability
What is your route to traceability

Traditional In-Situ Sensor Calibration

Until recently most humidity calibrations were performed on-site in-situ. Larger organisations with multiple instruments generally found it more convenient to have their own in-house calibration instruments with dedicated technicians working on-site. Smaller organisations unwilling or unable to invest in on-site calibration equipment had the option to engage the services of a commercial calibration provider.

In most cases, trained instrument technicians are required for in-situ calibration work; the equipment is brought to the probes and generally only one probe can be calibrated at a time. One of the main disadvantages of this process is the impact that it has on production downtime, as typically a salt or chamber based calibration can take more than three hours. Moreover, as the processes or control systems are interrupted during calibration, the actual conditions can be unknown.

Modern Ex-Situ Sensor Calibration

Companies keen to avoid the impacts of in-situ calibration and/or operational downtime caused by the replacement of failed hard wired instruments are opting instead for the flexibility and convenience of interchangeable sensors and modern portable calibration generators. Instead of bringing in equipment to calibrate in-situ, the technician brings pre-calibrated probes directly from the laboratory (on-site or external). Using interchangeable digital sensors, the pre-calibrated probes can be exchanged with the in-situ probes in seconds (known as hot swaps), saving time and avoiding operational disruption. If a wider system loop calibration is required, digital simulators are applied and provide any fixed values exactly and instantly. The old probes are then taken back to a calibration laboratory and calibrated accordingly. This adds the benefit that an external accredited laboratory can be used without issue.

Improved accuracy and traceability?

By ensuring that all calibrations are performed within dedicated laboratories as opposed to ad-hoc locations, better procedures and instrumentation can be utilised. In addition, time pressures are usually reduced as processes and monitoring systems are unaffected during calibration. As such calibrations are typically performed to a higher standard leading to lower associated measurement uncertainty (every calibration will have an uncertainty associated with it – whether it is defined or not). Overall in most circumstances these methods deliver greater reliability, improved traceability and importantly, reduces on-site workload and limits operational downtime.


CASE STUDY – Meeting the demands at the National Physical Laboratory, London.

National Physical Laboratory
National Physical Laboratory, London

When the National Physical Laboratory (NPL) in London needed to replace their entire building management system (BMS), they turned to Rotronic Instruments (UK) for an integrated solution to the sensors and calibration. The NPL was looking for both a complete range of temperature and humidity sensors and instrumentation, and the fulfilment of the calibration and commissioning needs of these instruments. Working closely with the project stakeholders, the Rotronic Instruments (UK) team developed a tailored solution, matching the instruments and service to the project requirements.

The decision by the NPL to replace the BMS was brought about by the need for tighter control, greater reliability and easier calibration. One of the key elements in achieving these objectives was the use of interchangeable probes. This immediately limited time-consuming and disruptive on-site sensor calibration to a minimum. Every probe’s digital output was calibrated in Rotronic Instruments’ (UK) UKAS accredited laboratory, and each transmitter’s analogue output was calibrated using a simulated digital input. To resolve any measurement errors in-situ between the calibrated sensors and uncalibrated BMS, each installed high accuracy instrument was loop calibrated and adjusted. Typical installations errors corrected for to date on the brand new BMS are ±0.5 %rh and ±0.25°C; a significant result for labs requiring tolerances of better than 1 %rh and 0.1°C.

Whilst the use of high performance instruments was essential, not every sensor location or application could justify this approach. However, mindful of the NPL’s long term objectives, even the lowest specification thermistor products were customised to provide long-term performance and low drift. Additionally, a robust commissioning procedure and training for key personnel was developed to enable ongoing commitment to delivering quality measurements. Finally, it was effective communication and regular on-site interaction with all the stakeholders that helped deliver a successful outcome to this substantial project.


Summary

All companies that need to perform regular monitoring and instrument calibration should be constantly reviewing their processes and questioning whether their operations and procedures are delivering the maximum return for their business. As increased regulatory compliance and demands for improved energy efficiencies continue to grow, traditional processes may no longer offer the optimum solution. An organisational mindset change may be needed to move calibration from being seen as a fixed cost to a process that can help deliver business objectives through ongoing cost and energy efficiencies.

With the advent of calibration methods that can significantly reduce in-situ disruption, downtime is minimised, labour costs are reduced and productivity improved. Using interchangeable digital systems increases the accuracy and traceability of calibrations, resulting in higher quality product.

Choosing the right calibration methodology may require new thinking and a different approach, but those companies that get it right will end up with a modern, flexible system that both achieves compliance and delivers long term cost and energy efficiencies to their business.

For more information on the NPL case study or how your business can develop innovative and efficient monitoring solutions please contact us.

Critical monitoring of wind turbines

The future is very encouraging for wind power. The technology is growing exponentially due to the current power crisis and the ongoing discussions about nuclear power plants. Wind turbines are becoming more efficient and are able to produce increased electricity capacity given the same  factors.

Picture2
Worldwide installed wind power per year in MW. (Source GWEC)

Converting wind power into electrical power:

A wind turbine converts the kinetic energy of wind into rotational mechanical energy. This energy is directly converted, by a generator, into electrical energy. Large wind turbines as shown in the picture, typically have a generator installed on top of the tower. Commonly, there is also a gear box to adapt the speed. Various sensors for wind speed, humidity and temperature measurement are placed inside and outside to monitor the climate. A controller unit analyses the data and adjusts the yaw and pitch drives to the correct positions. See the schematic below.

Wind Turbine
Schematic of Wind Turbine Systems

The formula for wind power density:

W   = d x A2 x V3 x C  where :

d: defines the density of the air. Typically it’s 1.225 Kg/m3 This is a value which can vary depending on air pressure, temperature and humidity.

A2: defines the diameter of the turbine blades. This value is quite effective with its squared relationship. The larger a wind turbine is the more energy can be harnessed.

V3: defines the velocity of the wind. The wind speed is the most effective value with its cubed relationship.

In reality, the wind is never the same speed and a wind turbine is only efficient at certain wind speeds. Usually 10 mph (16 km/h) or greater is most effective. At high wind speed the wind turbine can break. The efficiency is therefore held to a constant of around 10 mph.

C: defines the constant which is normally 0.5 for metric
values. This is actually a  combination of two or more constants depending on the specific variables and the  system of units that is used.

 Why measure the local climate?

To forecast the power of the wind over a few hours or days is not an easy task.

Picture3
Off shore wind farms

Wind farms can extend over miles of land or offshore areas where the climate and the wind speed can vary substantially, especially in hilly areas. Positioning towers only slightly to the left or right can make a significant difference because the wind velocity can be increased due to the topography. Therefore, wind mapping has to be performed in order to determine if a location is  correct for the wind farm. Such wind maps are usually done with Doppler radars which are equipped with stationary temperature and humidity sensors. These sensors improve the overall accuracy.

Once wind mapping has been carried out over different seasons, wind turbine positions can be determined. Each turbine will be equipped with sensors for wind direction and speed, temperature and humidity. Using all these parameters, the turbine characteristics plus  the weather forecast, a power  prediction can be made using complex mathematics.

The final power value will be calculated in “watts” which will be supplied into power grids, (see schematic on the right).  Electricity for many houses or factories can be powered by the green energy.

Picture4
Not ideal energy generating conditions!

Why measure inside a wind turbine?

Wind farms are normally installed in areas with harsh environments where strong winds are common. Salty air, high humidity and condensation are daily issues for wind turbines.

Normal ventilation is not sufficient to ensure continuous operation. The inside climate has to be monitored and dehumidified by desiccant to protect the electrical components against short circuits and the  machinery against corrosion. These measurements are required to ensure continuous operation and reduce maintenance costs.

What solutions can Rotronic offer?

Rotronic offers sensors with  exceptional accuracy and a wide range of products for meteorological applications and for monitoring  internal conditions.

Low sensor drift and long-term stability are perfect in   wind energy applications where reduced maintenance reduces operational costs.

The wide range of networking possibilities including RS-485, USB, LAN and  probe extension cables up to 100 m allows measurements in remote or hard to reach places. Validated Rotronic HW4 software makes it easy to analyse the data or it can be exported into MS Excel for  reporting and further processing.

The ability to calibrate  accurately using humidity standards and portable generators on site ensures continued sensor performance!

Comments or queries? Please do get in touch!

 

Temperature and Humidity Monitoring in Data Centres

Over the years there has been a rapid increase in large stand-alone data centres housing computer systems, hosting cloud computing servers and supporting telecommunications equipment. These are crucial for every company for IT operations around the world.

It is paramount for manufacturers of information technology equipment (ITE) to increase computing capability and improve computing efficiency.  With an influx of data centers required to house large numbers of servers, they have become significant power consumers. All the stakeholders including ITE manufacturers, physical infrastructure manufacturers, data centers designers and operators have been focusing on reducing power consumption from the non-computing part of the overall power load: one major cost is the cooling infrastructure that supports the ITE.

Data Centre Modelling
Data Centre Modelling

Too much or too little Humidity can make one uncomfortable. Similarly, computer hardware does not like these extreme conditions any more than we do. With too much humidity, condensation can occur and with too little humidity, static electricity can occur: both can have a significant impact and can cause damage to computers and equipment in data centers.

It is therefore essential to maintain and control ideal environmental conditions, with precise humidity and temperature measurement, thus increasing energy efficiency whilst reducing energy costs in Data Centers. ASHRAE Thermal Guidelines for Data Processing Environments has helped create a framework for the industry to follow and better understand the implications of ITE cooling component.

Rotronic’s high precision, fast responding and long-term stability temperature and humidity sensors are regularly specified for monitoring and controlling conditions in data centres.

Why measure temperature and humidity?

Maintaining temperature and humidity levels in the data center can reduce unplanned downtime caused by environmental conditions and can save companies thousands or even millions of dollars per year. A recent whitepaper from The Green Grid (“Updated Air-Side Free Cooling Maps: The Impact of ASHRAE 2011 Allowable Ranges”) discusses the new ASHRAE recommended and allowable ranges in the context of free cooling.

The humidity varies to some extent with temperature, however, in a data center, the absolute humidity should never fall below 0.006 g/kg, nor should it ever exceed 0.011 g/kg.

Maintaining temperature range between 20° to 24°C is optimal for system reliability. This temperature range provides a safe buffer for equipment to operate in the event of air conditioning or HVAC equipment failure while making it easier to maintain a safe relative humidity level.  In general ITE should not be operated in a data center where the ambient room temperature has exceeded 30°C. Maintaining ambient relative humidity levels between 45% and 55% is recommended.

Additionally, data centre managers need to be alerted to  change in temperature and humidity levels.

Rotronic temperature and humidity probes with suitable transmitters or loggers are most suitable for monitoring & controlling conditions in data centres due to their high precision and fast response with long-term stability.

With Rotronic HW4 Software a separate monitoring system can be implemented. This enables data center managers to view measured values and automatically save the measured data. Alarm via email and SMS, with report printout allow data integrity guaranteed at all times.

Dr Jeremy Wingate
Rotronic UK

Field Testing the new HL-1D Compact Logger – Up the Matterhorn!

Last week Rotronic launched their latest small compact temperature and/or humidity data logger!

hygrolog1_front
HL-1D Compact Logger UK RRP £73

With the Friday off work myself and a friend thought how better to test the impressive little logger than slinging it in a pack and carrying it up through sun, fog, snow and rain on an audacious weekend attempt to climb the 4478m Matterhorn in the beautiful Swiss Alps (I confess my friend could not care less about the logger aspect but was certainly up for the climb).

Matterhorn
Hornli Ridge of the Matterhorn 4478m

With no time for acclimatization, the climb would be grueling enough without carrying additional instruments, but thankfully the HL-1D is very compact and light. It has 3 year battery life, can store 32,000 readings and has high measurement accuracy of ± 3.0% RH and ± 0.3 °C. Of course the logger is designed more for monitoring office and work spaces,  transportation of products, production and storage environments, still we though it wise to push it to its limits!

Due to very poor conditions on the mountain we planned to overnight in a small hut at 4000m. So with our packs loaded we set off from the 2000m high gondola station above the beautiful village of Zermatt. But first ensured we were well fueled with ‘Apfel Strudel’ and coffee!

Breakfast HL-1D
Breakfast of kings!

The climb itself started at 3000m and the temperature quickly began to drop as we gained altitude.  At nearly 4000m the temperature dropped rapidly and clouds came in (shown by a rapid increase in the humidity). Luckily the Solvay Hut at 4004m provided welcome shelter and a ‘comfortable’ 3°C temperature (much warmer inside our sleeping bags).

Start of Hornli Ridge
At the base of the route proper

The morning showed that the cold temperatures and thick cloud had turned to more heavy snow fall, making any further progress even harder. The fresh snow combined with the debilitating effects of altitude sickness meant that we (wisely) decided to head straight down (this was just a quick weekend getaway after all).

Descent - more snow
Lots more snow on the way down!

The decent was challenging and navigation difficult. Snow fall was consistent most of the day and topped off by a steady shower of rain as we made our final walk back down to the gondola station (you can see the logger showing 100%rh as the top pocket of my bag becomes saturated in the down pour).

Zermatt
Relaxing back in beautiful Zermatt the following day – It’s sunny now!!

Back in Zermatt and we quickly find shelter to dry off and find a good spot for a celebratory beer and hearty Swiss meal.

What of our little logger? It provides a great record of the trip. Values safely recorded through the freezing temperatures and soaking rain.
Full trace of the logger can be found below; click on the image for more detail.

Matterhorn Trace
Matterhorn Trace

If you would like more info on the latest compact logger click here or for any other measurement queries please do not hesitate to contact us!

Dr. Jeremy Wingate
Rotronic UK

BlogShot – Rotronic High Precision, Fast Response Sensors for Temperature & Humidity Monitoring in Data Centres

There has been a rapid increase in large stand-alone data centres housing computer systems, hosting cloud computing servers and supporting telecommunications equipment, they are crucial for company IT operations around the world. Data centres must be extremely reliable and secure; many are wholly remote facilities.

Air conditioning is essential to maintain temperature and humidity levels within tight defined tolerances, thus ensuring the longest possible service life of the installed hardware.

Precise temperature and humidity measurement with fast reacting sensors is an absolute requirement. This increases energy efficiency whilst reducing energy costs. Additionally, data centre managers need to be alerted to even a small change in temperature and humidity levels. A separate monitoring system with networked alarms using fast reacting temperature and humidity sensors is installed.

Rotronic ‘standard’ HC2-S interchangeable temperature and humidity sensors are regularly specified for monitoring & controlling conditions in data centres due to their high precision and fast response with long-term stability. Used with a HygroFlex5 measurement transmitter analogue (scalable) or digital outputs are available exactly as required for interface with control systems. The loop can be validated electrically in minutes saving a significant amount of time. Probes can be exchanged rapidly when service work or periodic calibration checks are required.

Contact Rotronic for full product information

Tel: 01293 571000  Email:  instruments@rotronic.co.uk

Reducing UKAS calibration uncertainties

At Rotronic UK our UKAS laboratory have worked hard to make a name for itself in high quality calibrations and service. Thanks to constant improvements in measurement procedures the laboratory is growing into one of the most advanced commercial facilities in this specialised field. The ISO 17025 accredited calibration of humidity and temperature sensors and dew point instruments confirms performance and is increasingly a requirement of industry regulations and company quality management systems. The UKAS laboratory at Rotronic UK has spent the last two years increasing confidence in the calibrations performed and as a consequence lowering the Calibration and Measurement Capability (CMC) of the laboratory. Significant improvements have been made in the measurement procedures for dew point and temperature in air, enabling the following UKAS Accredited CMCs:

Dew/Frost point measurement (°Cdp/fp) • -60 to -40 °Cfp; uncertainty ±0.14 °Cfp • -40 °Cfp to +60 °Cdp; uncertainty ±0.11 °Cdp • +60 °Cdp to 70 °Cdp; uncertainty ±0.12 °Cdp

Temperature in air/ °C • -60 °C to 0 °C; uncertainty ±0.08 °C to 0.06 °C • 0 °C to +70 °C; uncertainty ±0.05 °C • +70 °C to +150 °C; uncertainty ±0.07 °C to 0.16 °C

Relative Humidity (RH)/%rh In the laboratory RH is derived from vapour pressure formulations. Improvements in dew point and temperature in air CMCs therefore affect the RH CMCs profoundly. The improvement lies in the range 0 to 70 °C; in the worst case RH CMC is ±1.0 %rh. In all parts of the HC2-S specified range covered by the accreditation the CMC is better than the specification of the probe. This is the first time this has been achieved. With the new temperature in air calibration range (-60 °C to +150 °C) and new dew/frost point calibration range (-60 °Cdp and up to +70 °Cdp) the laboratory’s RH calibration range has been extended up to 70 °C and 98 %rh. For example, at the new upper limit of 70 °C/98 %rh the CMC is ±0.6%rh and with these levels of calibration measurement uncertainty and range of accredited calibration services the purpose-built laboratory is one of the most advanced commercial facilities in the world.

Dr. Jeremy Wingate
Rotronic UK