Fixed volumes, such as steam drums, air separation equipment, or lengths of pipework which operate at pressure may require their operating pressure to be reduced by a process known as "Blowing Down".
During this "Blowing Down" process the fixed volume is depressurised at a rate that is either controlled by a valve, or a calibrated opening, which limits the rate at which the flow is released.
In some cases this blow down is an uncontrolled event as the valve used to block the pressure is thrown wide open as quickly as possible in an effort to achieve the quickest possible pressure let down.
This flow, which is normally, but not always, from a high pressure, will cause high noise levels which will be dangerous to plant personnel, and may well be environmentally unacceptable to nearby residents.
Where it is of assistance, we can examine the piping geometry and/or vessel size to determine the optimum back pressure for the let down timings and noise levels that you want to achieve.
The structural design of the Flo-Dyne Vent Silencer is given the same thorough attention as its process and acoustic design, with external forces such as wind, nozzle and seismic loads all being considered in the design.
Flo-Dyne's blow down silencer will be built with two key components, the inlet diffuser and the absorptive pack.
The inlet diffuser provides back pressure onto the inlet pipework and restricts the flow through the silencer and will, like an orifice plate, control the blow down timing of the system. The diffuser also acts as an acoustic device because it provides attenuation, primarily at low frequencies and is often considered a pressure retaining part which must be built to the same standards as the incoming pipework. CE marking of this component is often mandatory.
The absorptive pack is the second component, it provides little resistance to flow, and is made from tubes and panels of perforated steel sheet that have a porous material, such as glass fibre or rock wool packed in between. The choice of materials, perforations, packing materials and flow passage arrangement is crucial to the overall performance of the silencer.
Units may be mounted horizontally or vertically, with pads or cradle type supports being supplied as standard for easy installation.
A variety of weather-hoods are available to keep out rain, snow and sand.
Should you require, we can provide inlet nozzles with moving inlets that provide a significant range of axial and lateral displacement as well as allowing bending and rotational movement.
Equipment is available in a variety of materials, but most commonly in ordinary carbon steels, 3104(L) and 316(L) stainless steels.
