Road structure – process – or apparatus – Pavement – Vault cover-closure
Patent
1993-05-19
1995-03-28
Britts, Ramon S.
Road structure, process, or apparatus
Pavement
Vault cover-closure
52 20, 137364, E02D 2914
Patent
active
054011140
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to an insert for a shaft, in particular a ventilatable sewer manhole. The said insert consists of a dish-shaped body made of impermeable material, preferably plastic, and its interior space is connected by at least one connecting duct with the part of the manhole located beneath the insert, and this connecting duct can be sealed by a shut-off device.
Underground pipe systems such as sewers, water mains, cable ducts and similar must as a rule be ventilated. Such ventilation is particularly important in the case of sewer installations because hydrogen sulphide vapours are formed here by aggressive or putrefying effluent, and if inadequate ventilation is provided these vapours will combine with water of condensation to form sulphuric acid which attacks the structures. In addition, dangerous gases frequently form in sewers and if the ventilation system is inadequate, these gases pose a serious danger to the maintenance personnel.
As a rule, the ventilation is assured by providing manholes through which access may be gained to the sewers. These manholes are sealed off at ground level by manhole covers made from concrete, steel or cast iron in which an adequate plurality of ventilation openings is provided. When rain falls, however, the disadvantage of such a design is that surface water flows through these ventilation openings into the sewer. In the event of heavy rainfall, the amounts of rainwater accumulating may be considerable. In cable ducts, the ingress of large volumes of water creates the risk of short circuits occurring. The cross sections of sewer installations are often inadequately dimensioned to carry away the sudden build-up of large amounts of surface water. Given the nowadays frequently adopted practice of employing separate sewers to handle on the one hand dirty effluent and on the other hand clean water, in particular storm water, it is absolutely essential to prevent storm water from penetrating into the sewer system carrying the dirty effluent, because on the one hand the cross sectional dimension of the latter system is not large enough to cope with such large, suddenly accumulating volumes of water, and on the other hand the sewage treatment plants provided to handle the dirty effluent, and also any pumping stations that are present, become heavily overloaded when large amounts of water suddenly pour in.
It has therefore already been proposed (in U.S. Pat. No. 4,650,365) that an insert containing a dish-shaped section made of impermeable material should be positioned below the manhole cover. The internal space of this dish-shaped section is connected with the part of the manhole below the insert, and a shut-off device is fitted in the connecting duct. At its upper edge the insert possesses a laterally projecting flange which rests on the supporting flange of a manhole frame provided for a manhole cover, and between the two flanges a seal is installed.
In this known embodiment the duct shut-off device takes the form of a pressure-release valve which is normally closed, so that no surface water can enter via the connecting duct, and the valve opens only when an overpressure builds up either in the portion of the manhole below the insert or in the sewer to which the shaft is connected. Thus, the gases generated in the sewer can escape only if an appropriately elevated pressure is reached at which the valve is caused to open. Totally unrestricted ventilation of the manhole and of the sewer connected to it, via the ventilation openings in the manhole cover, is thus not permitted by this known embodiment. Aggressive and/or dangerous gases which form are therefore not continuously vented so that the disadvantages described further above still exist with this known type of insert.
U.S. Pat. No. 4,957,389 describes a manhole insert consisting of a dish-shaped structure resting on and forming a liquid-tight seal with a support projecting from the wall of the manhole, and a drain opening, closable by a plug, is provided in the bottom of t
REFERENCES:
patent: 1865387 (1932-06-01), Radomski
patent: 3173442 (1965-03-01), McKillip
patent: 3712009 (1973-01-01), Campagna
patent: 4067659 (1978-01-01), Campagna, Jr. et al.
patent: 4094346 (1978-06-01), Milo
patent: 4650365 (1987-03-01), Runnels
Britts Ramon S.
O'Connor Pamela A.
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