The new screen replaces an old 5 x 1.8 metre unit that was located within a Telemat asphalt plant on the site.

Finedoor supplied a 5 x 1.8 metre, four and two half deck screen inclined at 10.5° which was fitted into an existing structure. The new screen features pumped oil lubrication which was fitted in a tamper proof box and included an additional back-up pump with rapid change-over fittings.

The screen is constructed of 10mm thick rigid side plates with heavy-duty bolted- in deck frames and features twin overhead alloy steel shafts with two self aligning spherical roller bearings per shaft. Designed for end tensioned woven wire screen media, the screen is driven by twin 15Kw motors complete with vee-belt drives all mounted on a spring loaded motor base.

The pumped oil lubrication system which is mounted at ground level incorporates a 200 litre capacity oil tank and twin heater elements. All oil is retained in the tank which is located adjacent to the main mixing tower from which piping delivers oil and returned oil to and from the tank. Filtered oil is pumped continuously into each bearing, and is continuously drained from the screen centre tube and pumped back to the main storage tank. All the returned oil is filtered prior to entering the storage tank. Heat is absorbed by the oil as it passes through the bearings; this heat is then dissipated in the tank, but will accumulate.

To obtain optimum operating temperature of 60-70°C, an automatic air blast oil cooler circulates oil in the storage tank, again with oil filtration. The oil used is EP68, much lower viscosity; it can be mineral, not synthetic and requires an annual change.

The use of RAP materials, does not affect the operation of the system, as the oil absorbs heat, and cools the bearings as it passes through, and any excess heat is removed by the air blast cooler. Servicing at Runcorn is carried out at ground level, and only requires occasional visual inspection of oil pipes and general mechanical items.

Finedoor supplied a unit which has a storage tank, air blast cooler, filters, oil pump, electrical control panel, oil temperature and oil pressure monitoring; all of which can be viewed at ground level, and via multi-core cable, information can be made available to warn operators of either low level oil, low oil pressure, or non flow of oil.

After subsequent site visits the screen was manufactured and with the pumped oil unit was fully tested at the works. It was then installed, tested and commissioned at the Runcorn site by Finedoor engineers within the prescribed time frame.

The project was judged a complete success, Chris Ashley - Site Manager, commented, "After many years of screen problems at Runcorn Asphalt Plant, Finedoor were asked to install a new screen & oil system with the facility of pumped oil lubrication. All manufacturing dates were on target with good communications from the Finedoor team. The installation of the new systems was a great success with very few issues, which were soon rectified by an excellent fitting team & the installation was all within the set closure time.

The oil pumped lubrication system is an excellent upgrade to the previous oil tubes, as the oil is always at the correct operating temperature & far easier to check & maintain. Since the screen has been installed there have been no mechanical issues with a good after service care from the Finedoor team."