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One field device replaces a junk trap system consisting of several components.

The Privet Double Dumper® replaces a junk trap system consisting of two main valves – knife gate, ball or some other type – the junk chamber between the valves and two air evacuation valves. Its capability of handling impurities is comparable to that of a metal-seated ball valve.

New standard of safety.

A traditional junk trap allows full through-flow at process pressure, if both of the main valves are accidentally left open at the same time. For example with a 6-inch pipe at 3 bar process pressure, about 2000 cubic metres of hot pulp will flow out from the pipe per hour.

The Privet Double Dumper® will not allow through-flow in any of its pos- itions; it is a feeder, not a valve design. Because of its simple design, the Double Dumper® is inherently less sensitive to malfunctioning than a traditional multi-component junk trap.

Compact design.

A conventional junk trap designed with knife gate valves has a height of roughly 1000 mm in 6-inch size. For other valve types, the height will be even greater.

The height of a 6-inch Double Dumper® is only 350 mm. It also weighs much less.


HighTech Finland

Privet • Double Dumper

A state-of-the-art solution for intermittent reject removal instead of conventional junk traps.

With its straightforward design, the Double Dumper® feeder replaces a conventional junk trap system consisting of several valves and a junk chamber.

It is safer, needs less space and is easier to install in the mill. The connection to the process computer is simple and it does not require a software package with the operating sequence logic.

Simpler and less costly to install and connect to the process computer.

Each of the four valves of a traditional junk trap needs one pneumatic line and three cables – one for the solenoid valve and one for each limit switch. This means installing four pneumatic lines and twelve cables.

The Double Dumper® needs only one pneumatic line and three electric cables.

The traditional junk trap needs 12 I/O’s, one for each electric cable, to connect it to the process computer. The Privet Double Dumper® requires only three I/O’s. This means savings in lines and cables, in installation work and in connections to the process computer.

Simpler process control.

The valves of a conventional junk trap need to be opened and closed in a certain sequence. The upper valve is normally open. When the junk space is full, the upper valve is closed and the lower valve is opened to dump the junk. After the lower valve is closed, the air is evacuated through two air evacuation valves, which need to be closed before the upper valve reopens.

The process computer requires a software package which incorporates this operational sequence logic. Another possibility is to build a separate logic panel for the same purpose.

Because the Privet Double Dumper® is just one field device, it does not need a software package or a separate logic panel. This is an additional saving compared to the traditional junk trap.


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