Kessel 99 403.10 Guide Pour L'installation page 25

In cases a) to d), the discharged water from the separators
is intended to be fed back into the public drainage system.
If the discharged water is to be returned into waters, this is
only possible in individual cases following clarification with
the local water authority.
Separators used in case d) are used in systems for the re-
striction of hydrocarbons in waste water containing mineral
oil in the sense of Part E Paragraph 2 of Appendix 49 of the
waste water regulations.
The level of hydrocarbons required by regulations in cases
c) and d) of 20 mg/l is considered to have been observed.
2.2 System description
The illustration shows a coalescence separator cistern instal-
led in the ground of Class A/B.
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➀ Drain without odour trap
➁ Light fluid separator
➂ Inlet with odour trap
➃ Outlet with self-actuating closure
➄ Guide tube
➅ Floater
➆ Upper section
➇ Cover
➈ Sampling chamber
➉ Backwater valve
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Installation
2.3 Functional description
The separators separate light fluids and sludge out of the
waste water by means of gravity. Light fluids refers to fluids
of mineral origin with a density of ≤ 0.95 g/cm3, which are
insoluble or only slightly soluble in water, and which are
non-saponifiable. These do not include stable emulsions,
fats and oils of vegetable or animal origin. Light fluids float
up in the separation chamber and collect at the surface.
Sludges, which are heavier than water, sink to the bottom
and form a sludge layer.
Coalescence separators, like oil-fuel separators, work on the
principle of gravity. To increase the separation performance,
the tank also contains a coalescence insert. This cylindrical
insert has two functions. Firstly, it affects the flow in the se-
parator, and secondly it "filters" all the waste water through
the coalescence material.
When waste water containing oil flows through this filter fab-
ric, very fine oil droplets that can no longer be separated out
by gravity collect on the coalescence material, and combine
to form large oil droplets. When these reach a sufficient size
to create buoyancy, they detach themselves from the filter
material and rise to the surface.
Light fluid separators are equipped as standard with a
self-actuating closure.
When the maximum oil storage volume is exceeded, this
device closes the outlet into the drainage system. This pre-
vents the escape of light fluids into the drainage system. This
safety device consists of a guide tube full of water, which
houses a float.
The float is carefully designed with regard to its weight, so
that it floats in water, and sinks in light fluid (up to a density
of 0.95 g/cm3). When the maximum oil storage quantity is
reached, oil flows through the lateral openings into the float
guide tube. The float then sinks, reliably shutting off the out-
let of the separator.
The self-actuating closure of a separator is an "emergency
closure valve". When actuated in an emergency, the separa-
tor must be taken out of service and maintained.
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