Electricity + Control July 2015

STANDBY + BACK-UP VALVES + ACTUATORS

ROUND UP

Oil control cartridge valves available throughout Africa

As part of the new joint venture into Af- rica, the Hytec Group has increased its distribution and support of the full range of Bosch Rexroth Oil Control cartridge valves throughout sub-SaharanAfrica.This expanded support will enhance the Group’s logistical, sales and support capabilities of the products, and includes amore competi- tive pricing structure for this series. The valve range simplifies conventional compact hydraulic systems, and enhances hydraulic circuits where space and weight present fundamental application con- straints. Bosch Rexroth cartridge valves are characterised by a very long service life: at an operating pressure of 350 bar,

quirements, facilitating a more efficient hydraulic operation. Enquiries: Louis Roode. 11 573 5400 or email louis.roode@hysa.co.za

the cartridge solenoid valves are rated for a product life of 10 million cycles. The unique design of the cartridge valves reduces the amount of interconnecting pipework required within the hydraulic circuit through a customised manifold. This reduces the overall weight, and space requirements, of the machine, resulting in decreased power requirements – contrib- uting to better all-round energy efficiency. Because the interconnections of piping within a conventional hydraulic system are a common source of fluid leakage, the compact design and reduced piping requirements of the cartridge valves also reduces inspection and maintenance re-

General purpose globe control valves

Mitech ’s general purpose Globe Control valves offer superior performance while permitting easy, fast and inexpensive maintenance. The standard Mitech Globe control valve can be used for many applications and offers high po- sitioning accuracy and tight shut-off together with compact size and robust construction. Due to the modular design it can be easily adapted to satisfy many special requirements such as high or low temperature, corrosive duties, three-way configuration and high pres- sure drop applications. The valves are available from the standard type up to the specially designed severe ser-

vice valve in ½” to 24” NB and up to ANSI 4500. The valves may feature tight shut-off, low noise, cavitation control and energy dis- sipating trims.The entire Mitech range of control valves utilise the clamp in place, free floating seat design. All trim components are designed to clamp in place so the valve can be quickly configured to the user’s specific process needs.The free float of the seat and plug during assembly means that stem, plug and seat alignment is easily achieved.When compared to alternative designs, the free float design provides the user with longer stem seal life and better valve shut-off performance.The simplicity of build also means that maintenance is quick and easy, with no special tools required to achieve the design performance of the valve. Enquiries: Pieter Badenhorst.Tel. 011 927-4850 or email enquiries@mitech.co.za

Pressure testing of Koeberg's containment building

Recognised as Eskom ’s most consistent and reliable power station, Koeberg is the only nuclear power station in Africa. Koeberg has a pressurised water reac- tor design. Featuring the largest turbine generators in the Southern Hemisphere, Koeberg is also themost southerly-situated nuclear power station in the world. With International Law stipulating that all con- tainment buildings of all nuclear plants have to be pressure tested every ten years, Eskom contracted Rand-Air to facilitate the assignment. The purpose of the pressure testing of the containment building at Koeberg was to ensure that there was no leakage which could be harmful to the surrounding envi- ronment and public. Using ten PTS916 Rand-Air units running through desiccant dryers, dry oil-free air

was pumped into the containment build- ing. Both the inner and the outer sector of the building were surveyed before, during and after the test.Water particles have a big influence on pressure testing and the end result. We were required to match 18 °C in temperature of the air going into contain- ment. Heat exchangers and chillers reduce the pressure testing time by a few hours allowing for control of the air pressure dis- tribution.The requirement for the pressure testing was minus 20 °dew point - minus 40 was achieved. The pressure test took between seven to eight hours. It took two and a half hours to reach a pressure of one bar.The procedure stops for eight hours when it reaches one bar, this is key in ensuring that everything is stable enough to continue to four bar. The process requires the go ahead from

two parties namely Électricité de France (EDF) and Eskom. It is critical to monitor the progression thoroughly as damage to the equipment inside the building could be detrimental. The pressure test at Koeberg was a success. Enquiries: Visist www.eskom.co.za

Electricity+Control July ‘15

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