Model AGVC
LogoManufactured in Australia
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The Delatite Noise Reduction Trim has been designed to reduce Noise,
Velocity and Vibration in control valves by using a number of drilled hole
cylinders and pressure reducing flow chambers.

High pressure drops in gaseous flow applications can cause premature valve
failure due to uncontrolled vibration which can over time cause trim and
valve failure.
It is not uncommon for continuous vibration to cause stem failure and or

High pressure drop in gaseous flow application can lead to high flow velocity
which is the main cause of excessive noise.

By controlling flow velocity and turbulence you can control valve noise levels
and valve vibration.
The DEL-LNT can effectively reduce noise levels by up to 30dBA

In a single seated control valve the flow travels from
P1 (upstream Pressure) to P2 (downstream pressure)
The gas takes a very large pressure drop just after the seat of the valve which
is also the point of most constriction in the valve body. This point is known
as the vena contracta.
As this point is the most constrictive in the valve this area also experiences
the highest velocity as shown in figure
The problem becomes quit clear when you overlay the velocity profile with the
pressure profile.

In gaseous applications where there is a large pressure drop across the valve the
flow velocity is increased greatly at the valve vena contrata which can generate
velocities in the valve which can reach sonic velocity. These sonic velocities
can generate high noise and vibration levels within the valve even though inlet
and outlet velocities are relatively lower.
The solution to high flow velocity is to gradually reduce the pressure within the
valve without any large pressure drops.
By doing this flow velocities are reduced which in turn reduce noise levels and

The drilled hole stages within the trim break up the flow into small stream and
also create back pressure, the pressure chambers between the stages allows for
a controlled expansion of the gas and help reduce turbulence.
This all helps to reduce velocity, vibration and control valve noise
Flow Profile through trim
The Delatite DEL-LNT has been designed to use a standard plug and seat with the noise reduction trim taking the place of the seat retainer.
By using this design the flow control is still performed by the characterized plug in the valve seat.
Noise reduction is performed by the DEL-LNT trim, with this design the pressure drop is shared between the plug/seat as per the standard Delatite control valves and
the velocity/noise is dealt with by the DEL-LNT trim.
One of the major factors to consider with noise reduction trims is the flow
velocity through the valve.
Attention must be given to velocity at the vena contracta but as the pressure
drops in a gaseous application the gas can expand, for this reason Delatite have
designed expansion chambers into the trim allowing the gas to expand as it
leaves the drilled hole section of the trim. The gas is then forced to contract as
it goes through the next set of holes, this action helps control velocity and
dissipate energy.

The Delatite DEL-LNT is designed for optimum performance at a velocity of
.3 mach at the valve discharge.
Consideration needs to be given to all flow areas of the valve to ensure .3 mach
is not exceeded. Areas like the valve inlet, the valve gallery area, and the valve
outlet must all be considered.

The DEL-LNT fit into all standard Delatite control valves taking the place of
the standard seat retainer.
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