The Process Engineer from a wastewater company got in touch with AKO UK about an application involving recycling astroturf media, and were interested in air operated pinch valves for the process. They were looking to use a pinch valve to simplify the separation of a combination of sand, rubber and lightweight media such as blades of grass from various liquids on one of their upper flow classification units.

The key requirements were –

  • The pinch valve needed to close/constrict uniformly around the sleeve and not from just two sides.
  • They wanted the pinch valve to have a full bore opening.
  • Suitable for 3 inch pipe.
  • Throughout material was to be a non chemical sandy material with rubber gravity fed from 2m high tank.
  • Very low temperature, ambient.
dual separation screening unit

Reliable Screening/Separation System

The standalone unit is designed to be incredibly easy to transport and used on a daily basis. With its “plug and play” design along with the ability to separate liquids and solids ranging in size from 40mm to 63 microns, this separation unit is truly versatile.

This bespoke machinery features a tank with an upward flow, where the media from recycled astroturf weirs over the top in a ripple motion. The media inside the tank separates based on the diversity of the particles, and forms layers. The sand gravitates at the bottom, the middle layer is rubber, and the top layer includes any lightweight media which overflows to the top, such as blades of grass.

The VF type Pinch Valves from AKO that this machinery is equipped with are used as discharge points. The positioning of each valve is in the centre of the layers inside the tank, and an upper flow period takes place. As the upper flow forms, the layers become flattened out.

VF080.03X.31.30LA
Pinch Valves used within this application – VF080.03X.31.30LA

VF model, air operated, bore sizes DN80, aluminium body, aluminium flanges PN10/16 with mild steel bushings, natural rubber abrasion resistant sleeve.

There are manual knife gate valves installed on this machinery as well as the pinch valves. The knife gate valves are used for flow control, to be partially opened to a desired opening using a hand wheel. The pinch valves are open with a full bore while the tank is being filled, and then closed using 2.5 bar air pressure while the media is separated. Once the separation process is complete, both pinch valves and knife gate valves are opened to discharge the water and the end of the process.

The waste water company were aware that it was possible for the pinch valves to be used for flow control by using a proportional control system, which would mean the knife gate valves would not have been needed, but they decided that the electrical set up of the flow control system was too complicated for their needs.

With the development of this machine the wastewater company have ensured that productivity is optimised allowing operational costs and on site working time to be kept to a minimum. Whether simply dewatering sand, screening problematic rag/digestate or washing products with the use of the integrated spray bar system, the multifunctional separation unit can give you a fast inexpensive temporary or permanent solution to your processing needs.

Applications Suitable for this Screening Unit Using Pinch Valves

  • Rag removal from sludge
  • Grit removal from sludge
  • Temporary import screen
  • Pre screen prior to centrifuge
  • Post digester screen
  • Screen for river dredging
  • Digester cleaning
  • Lagoon cleaning
  • Mobile Dual sand plant
  • Tanker waste screen
  • Wastewater screen
  • Wet waste management
pinch valves for separation

Pinch Valve Performance in Filtration System

The wastewater company are an Original Equipment Manufacturer, who commissioned this screening unit 11 months ago, after testing with product in their workshop and ensuring that the installed valves work well.

The end user has been using the mobile unit for the past 10 months and have reported back that they are very happy with the simple construction and performance of the AKO Pinch Valves. The waste water company purchased spare natural rubber sleeves at the time of ordering the pinch valves themselves, so that they had spares to supply to the end user with the machinery. However, to date the end user is yet to replace the internal rubber sleeves inside the valves while they are performing daily.

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