Valmet Flowrox SKW DN50-600, Installation Maintenance And Operating Instructions, Page: 34 / 53

4SK70EN - 5/2023
6
2 Introduction
2.1 Applications and purpose of use
Flowrox Slurry Knife Gate valves (SKW) and (SKF) are
intended for industry medium and slurry applications. They
are bi-directional and are installed between flat flanges to
shut-off or open flow within instructed temperature and
pressure limits.
2.2 Restrictions on use for SKW and SKF
valves
The valve must not be used to throttle the flow in any way,
nor should the gate be left in partially opened or closed
position as this will lead to premature failure.
The valve temperature and pressure range must not be
exceeded. The temperature ranges are given in Table 2 for
standard sleeve materials. Check the pressure class from the
valve type plate. Do not use higher pipeline pressure than
rated for the valve.
Table 2. Temperature ranges for SKW and SKF valves.
Ring sleeve material
NR NBR EPDM
Max valve operating
temperature °C (°F)
0 to 75 (32
to 167 °F)
0 to 100 (32 to
212 °F)
0 to 100 (32
to 212 °F)
2.3 Using the valve in explosive conditions
This valve type is not designed for Ex-areas.
For use in explosive conditions the valve must have the
required Ex-classification and the grounding cables must be
connected to earth. For more information, contact Valmet
Flow Control.
2.4 General description
2.5 Principle of operation
Flowrox SKW and SKF valves are built with a cast or welded
body and feature a heavy-duty stainless steel gate as a
standard structure. Removable ring sleeves on both sides of
the gate provide a bi-directional bubble tight seal.
In the open position the two ring sleeves seal against each
other in the centre of the valve, providing a full bore through
which the medium can travel. Main components are shown
in Figure 1. Valve main components.. Closing the valve forces
the gate progressively down between the two mating ring
sleeves, until it reaches the fully closed position. When the
valve is fully closed, the ring sleeves push against both sides of
the gate, effectively sealing and completely containing the line
pressure. Any medium discharged between the ring sleeves
during open/close strokes is collected to the valve body cavity
and drained or flushed through the flushing ports.
The secondary seal is located in the upper part of the body.
On every valve stroke, it wipes the gate and lubricates it
with silicone grease. Easier actuation and minimum wear
are achieved. There is no need to remove the valve from the
line when replacing the secondary seal, but in tight or unsafe
conditions it is unavoidable.
Figure 1. Valve main components.
No. Description No. Description
1 Valve body 7 Secondary seal
2
Gate 9 Protective plug (on
flushing port)
3 Tower 12 Bottom cover plate
4 Ring sleeve A Valve body cavity
The valve must not be used to throttle in any way,
nor should the gate be left in partially opened
or closed position as this will lead to premature
failure.
This valve is intended for on-off operation only. Ring sleeves
are easily replaced, and are available in a number of molded
elastomer options to suit different conditions.