Energy savings company aims to offer more holistic solution

12th July 2013

By: David Oliveira

Creamer Media Staff Writer

  

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Gas solutions provider Shield Technologies expects to roll out its first air-leak detection survey this month for a transport company in Bloemfontein.

“The compressor that the transport company is using has the correct capacity and duty cycle for the tools being used, but there is insufficient compressed air to drive the tools used for various applications, owing to leaks in the system, CEO Wayne Holt tells Engineering News.

“If the leaks are repaired, the compressor will operate at a level much lower than full capacity and increase production,” he adds.

The project opportunity arose after Shield Technologies completed a similar assessment of the transport company’s welding-gas leaks in December last year.

Typically, compressed air accounts for about 10% of the total electrical power consumed by industry, says Holt. According to research undertaken by the University of Cape Town (UCT), compressed-air costs over a ten-year period are split between 10% maintenance, 15% capital and 75% energy.

The UCT study also found that 30% of the total electricity used is expended on compressed air that is wasted; therefore, potential savings could be reaped through the introduction of simple and cost-effective measures that reduce this avoidable waste without compromising production.

Holt points out that Shield Technologies identified a gap in the local market two years ago, after it had become apparent that the majority of its client base often uses air compressors.

Shield Technologies’ leak-detection service started with the repair of welding-gas leaks and after realising how small the market was for this service and because of the advancements in leak detection technology, it decided to expand the service to include all industrial-gas leaks, including compressed air, argon, hydrogen, oxygen, helium and nitrogen.

“The aim has always been to help industries save energy,” states Holt, noting that compressed air is an inefficient use of energy.

He recommends that leak surveys be carried out at least twice a year to save costs and eliminate the risk of downtime associated with large ruptures.

“Currently, less than 10% of South African companies using compressed-air systems conduct leak-detection surveys. This is prob- lematic because leaks will always occur, especially at joints and fittings, but very seldom on the pipes themselves. If you consider that an air leak the size of a R2 coin can cost up to R100 000 a year – and that is based on State-owned power utility Eskom’s 48c/kWh electricity costs, which are now much higher – it becomes clear how costly air leaks actually are,” says Holt.

He attributes the problem of poor leak detection to the lack of technical training that artisans currently have. Artisans, Holt notes, need to be properly trained in using air- and electric-powered tools, as well as in the benefits and risks associated with using both technologies.

“While air-powered tools are more robust, electric-powered tools are more energy efficient, but they need to be replaced more regularly, as they are more prone to failure,” he says.

However, the cost of electricity used to power air tools is still high; therefore, if artisans are trained appropriately to detect leaks in compressed-air systems quickly, the technology will prove to be of greater benefit to a company than the less robust electric-powered alternatives.

Leaks are not only a direct source of wasted energy but also an indirect contributor to operating costs. As leaks increase, the system’s pressure drops and air tools function less efficiently, which affects production. Often, the only solution is to increase generation pressure to compensate for the losses, which results in using unnecessary compressor capacity, explains Holt.

Increased running time can, in turn, also lead to additional maintenance requirements and increased unscheduled downtime, he says.

Initially, Shield Technologies used an oxygen meter for leak detection. “When a leak occurs in a compressed gas system, oxygen is pushed away from the leak. Gas leaks can be detected on the system by running the oxygen meter across the affected area, which will then alert the operator of a drop in oxygen levels,” Holt states.

However, ultrasonic detectors are a much more efficient and convenient way of detecting leaks, as they can be used from a distance. This is particularly effective when detecting leaks in a compressed air system where the pipes are installed at roof height.

Holt notes that the company uses the internationally recognised SDT270 ultrasonic detector to identify compressed-air leaks. The system is manufactured by Belgium-based manufacturer of ultrasonic measuring instruments and related technology, SDT International.

“The SDT270 ultrasonic detector provides the most precise and cost-effective solutions for leak detection, as any compressed-air leak can be quickly and safely identified from up to 80 m away, even in a noisy factory environment. This range is increased to 100 m when the SDT270 is used in conjunction with SDT’s latest parabolic dish attachment,” he explains.

Holt adds that compressed-air leaks generate friction, which, in turn, creates ultrasonic sound waves that cannot be heard by humans. “Ultrasounds have a frequency of more than 20 000 Hz. The friction created by leaking gas is specific and can range from 38 000 Hz to 40 000 Hz, which is completely undetectable by the human ear.

“High-frequency sounds are more directional than lower-frequency sounds, which makes it easier to pinpoint the source, even amid other background noises,” he points out.

In addition to being highly accurate, the SDT270 ultrasonic detector is also user friendly. The basic setup in control situations consists of a hand-held unit, with headphones, a meter, a sensitivity adjustment and several different sensors. Some applications, where leak tightness testing integrity is measured, also require a transmitter.

“The user simply has to walk with the unit at a standard pace to allow for scanning along the X-axis and Y-axis. Once the leak has been detected, the area can be identified using a laser pointer or gun sight on the parabolic dish, or the leak can be more accurately detected using a flexible sensor with an attached focusing cone,” explains Holt.

The leak is then marked with a paint marker and the relevant maintenance team can be commissioned to fix it using the correct fittings and sealant, as well as a recommended O-clip, which is crimped onto hoses, where necessary.

Although Shield Technologies does not undertake the repairs, Holt adds that the company has a comprehensive list of recom-mended pressurised-equipment installers that are fully authorised and equipped to undertake the relevant repairs.

Edited by Tracy Hancock
Creamer Media Contributing Editor

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