Vocal about Valves
Michael Schmid - Lindenmayer, Managing Director, Putzmeister Concrete Machines talks about s-valve technology.
For the daily tough operations at the construction site, a concrete pump has to be powerful, unflagging, robust, undemanding and reliable. This especially applies to smaller construction sites where they have to render versatile services as inexpensive as concrete pumps. In the case of large projects with high-rise buildings at long distances, conveyance for these machines has to offer real power, and this has to be done with minimal mass force, quiet operation and quick switch-over.
The latest concrete pump technology is based on the s-valve technology. In India, a majority of the market still uses the outdated gate valve pumps, which phased out in Europe in the 70s because of high wear and tear. S-valve technology on the other hand facilitates the long service life of the main wear parts and has low diesel and hydraulic oil consumption. It also allows pumping with higher concrete pressure to reach a higher output at greater heights and renders lower operating costs.
In this technology, pump operation becomes more comfortable, and the valve is easy to maintain due to the close circuit of the pump. Reverse pumping is also possible, which solves a choking problem in many cases without the need to disassemble the pipeline. S-Valve techno-logy has been proven to be the most economical way to switch from one delivery cylinder to the other. The advantage of one side wear and tear and the ability to adjust the gap between the spectacle plate and the wear ring adds to its benefits.
With concrete pumps
Concrete pumps equipped with ‘s-transfer tubes’ have been setting new world records in vertical and horizontal delivery. The s-valve is extremely useful wherever ext-remely stiff and abrasive mixes of concrete are encountered. The Putzmeister concrete pump created a world record in long distance-concrete conveying at the French Le Refrain with 2,015 m and a record pump height of 606 m at the Burj Khalifa Tower in the UAE in 2008. In both cases, the pumps and accessories were still not operating within their limits.
The s-valve is the first choice for jobsites with concrete pressure above 85 bars. This is especially useful for long pumping dista-nces over stationary pipelines. The Putzmeister s-valve is especially designed for long life and high concrete pressure. This results in long service intervals and increased availability of the machine. To extend its life, the inside wall can be rebuilt by hard face welding. The s-tube that is manufactured out of thick-walled, special cast steel is designed for difficult, abrasive concrete. The s-transfer tube masters the most difficult pumpable concrete such as viscous, hydro concrete mixes made up of crushed quartz, granite or basalt with a consistency of up to K1 (1"slump) and a grain size of up to 63 mm.
The spectacle wear plate is fitted in the hopper to the openings that lead to the delivery cylinders. The wear ring is fixed to the inlet opening on the s-transfer tube and the thrust ring lies between the wear ring and s-transfer tube entry. Because of the very abrasive mixes, this 3-piece system is subjected to many different types of wear and load stress while the pump is in operation. The low-lying agitator that is driven on both sides keeps the mix homogeneous and guides the concrete directly to the front of the cylinder openings without sucking the air, thus incre-asing its efficiency. The optimised hopper shape reduces concrete settlement and residual concrete. It is also easy to clean.
As and when there is wear and tear, the automatic ring optimally seals the system, preventing it from bleeding out of concrete lines through the fine gaps caused due to the concrete’s abrasive nature, hence reducing the danger of blockage. This automatic ring compensates for the wear and seals automatically, thus ensuring an even wearing of parts and a long service life.
They are made of…
The s-valve has very few wear parts and all its parts are easy to change. The hopper remains mounted when the few wear parts require replacement. Hydraulic and switch-over cylinders are outside the concreting area and remain clean. The delivery pistons are centrally lubricated for a safer and longer service life. The hard-chrome layer of the delivery cylinders assures an even longer service life of the pistons and the cylinders and protects against corrosion. The non-contacting end-position impulse switch of the pump cylinder is wear proof.
(Communication by the management of the company)