IES80707B2 - A gas-extracting device and method of using same for reducing pressure under buildings - Google Patents

Abstract

The present invention refers to a gas-extracting device comprising an enclosed one-piece moulded chamber having an extract pipe and at least one inlet pipe for providing fluid communication between the interior of the chamber and at least one perforated pipe. In an alternative embodiment, the gas-extracting device has a non-rectangular base and a cover spaced apart from the base, an extract pipe connection means for connecting he chamber to an extract pipe and at least one inlet pipe connection means provided on the side walls, for connection to at least one perforated pipe. The invention also relates to a method of reducing underfloor pressure in buildings using the above gas-extracting device.

Description

A GAS-EXTRACTING DEVICE AND METHOD OF USING SAME FOR REDUCING PRESSURE UNDER BUILDINGS.

The present invention relates to gas extracting devices for a building and particularly t devices for lowering gas pressure in the ground under buildings having high radon concentrations. The invention also relates to a method of using the device for reducing pressure under buildings.

It is estimated that there are 60,000 houses in Ireland which have levels of Radon concentration in excess of the recommended reference level of 200 Becquerels per cubic meter. These are houses where remedial works are recommended in order to lower Radon concentration to safer levels.

Radon is a radioactive gas which is exhaled from the ground and can concentrate within buildings to reach levels which can bring about an increased probability of lung cancer for the occupants. Radon gas is heavier than air, and its presence within buildings is mainly accounted for by the fact that air pressure within buildings is generally slightly lower than the pressure outside the building, or in the ground under the building, thus this pressure differential results in a slight suction effect from the interior of the building leading to Radon gas seeping into the building from the ground under the building.

The most reliable method of reducing Radon levels within a building is based on reducing the pressure in the ground under the building.

In order to achieve this it is known to use a sump, pipe and fan as indicated diagrammatically in Figure 1. A Radon sump is intended to facilitate depressurisation of the ground under a building when suction is applied to the extract pipe.

Thus the primary purpose of a sump is to provide a pressure equalisation chamber. The sump should act to allow the lowered pressure field to extend readily and equally in all directions. To achieve this purpose a sump which is large in plan area is desirable. Such -2a large sump however, apart from being heavy and awkward to place has an inbuilt structural problem. The roof, because of its large span may collapse under the weight of the concrete poured overhead. The sump of the present invention avoids this difficulty while achieving the advantages of a large span sump.

The secondary purposes of an underfloor gas sump are: a) To ensure that the end of the extract pipe is not obstructed. b) To allow condensation flowing back from the extract pipe to drain away.

One known sump is disclosed in United Kingdom patent specification no. GB 2, 262, 297 and comprises a gas collecting chamber in the form of a pre-cast concrete or plastics box with a separate base and cover. The sides are perforated with venting apertures and several larger holes to which a ducting system may be connected. The sump is installed before constructing the ground floor slab of a building and surrounded with rubble. A pipe leads from the larger holes to vent gas to atmosphere and the completed installation may be covered by an impermeable membrane prior to floor construction.

This sump has several disadvantages associated with it, namely that it is heavy and expensive to produce. Furthermore, its dimensions are limited by the structural and practical difficulties mentioned above.

Another prior art sump is disclosed in Irish patent specification no. 76310 which describes a gas sump comprising an enclosed one-piece moulded chamber having a rectangular base. There are side walls on the base which support a rectangular cover. An outlet pipe spigot is provided which connects with the interior of the chamber and there are several gas inlet holes in the side walls.

The disadvantage of this sump also is that the perforated surface should be as large as possible in order to maximise extraction capability. However, a sump which takes the form of a perforated box cannot be enlarged much beyond a certain critical size without creating a structural problem, namely the collapse of the cover of the sump when concrete -3is poured overhead. Therefore sumps of the prior art tend to be small and do not therefore maximise capability.

The existing method of reducing underfloor pressure using known sumps has certain disadvantages. Since these sumps take the form of perforated boxes the suction cannot easily be arranged to favour a particular direction. This is a disadvantage if the installer is constrained to place the sump beside a wall or in a comer. It presents an even greater difficulty if the sump is placed outside the external wall of a building with the intention of drawing air from the interior of the building (under floor level).

A further disadvantage of the method is that the suction can only be exerted at the point where the sump is located. In the method in use the sump is installed in one of the underfloor compartments. It is recognised that the internal walls and their footings obstruct the extension of the lower pressure into adjoining compartments.

The practice, accordingly is :(a) in the case of blockwork/brickwork walls to form opes in the walls at hardcore level. (b) in the case of reinforced or mass concrete walls to provide separate sumps in each compartment (this is expensive) or to lay pipes through the walls, the pipes to be open on the remote end and communicating with the sump at the other end (since the sump is perforated this is ineffective.) The present invention seeks to alleviate the disadvantages associated with the prior art.

The present invention accordingly provides a gas-extracting device comprising an enclosed one-piece moulded chamber having an extract pipe and at least one inlet pipe for providing fluid communication between the interior of the chamber and at least one perforated pipe. -4In a first embodiment of the invention, the gas-extracting device has a non-rectangular base and a cover spaced apart from the base, an extract pipe connection means for connecting the chamber to an extract pipe and at least one inlet pipe connection means provided on the side walls, for connection to at least one perforated pipe.

In a second embodiment of the invention, the gas-venting device comprises a chamber having inlet pipe connection means provided at various acute and obtuse angles from a central section of the chamber. Preferably the inlet pipes connection means are provided at angles of 60° and 120° to each other.

The extract pipe connection means and the inlet pipe connection means may comprise spigots, sockets or short lengths of pipes capable of sealingly engaging with pipes having perforations. The connection means will hereafter be referred to as spigots for simplicity.

The perforated pipe may comprise either rigid or flexible piping.

The present invention also provides a method of reducing underfloor pressure in buildings comprising the following steps: Placing a closed (non-perforated) chamber in a permeable layer below floor level; connecting the chamber to an extract pipe; connecting perforated elements to the chamber via spigots, sockets, or openings, or additionally via pipe bends and/or pipe lengths, to achieve suction which can be exerted in the vicinity of the chamber, or at a point or points remote from the chamber or which can be aimed in desired directions.

The present invention will now be described more particularly with reference to the accompanying drawings in which are shown two embodiments of the gas-venting device of the present invention.

Figure 1 is a diagrammatic representation of the prior art arrangement of sump, pipe and fan for extracting dangerous gases such as radon; -5Figure 2 is a diagrammatic representation of the use of the device of the present invention as a manifold device; Figure 3 is a perspective view of a sump in accordance with a first embodiment of the device of the present invention; Figure 4 is a plan view of the device of the present invention in accordance with the second embodiment; Figures 5(a), 5(b) and 5(c) and Figures 6, 7 and 8 are plan view of alternative uses of the device shown in Figure 4.

In the first embodiment of the gas-extracting device of the present invention, the device comprises a preformed sump manufactured in plastics or other suitable material. The device of the present invention has the added advantage that it may be used as a manifold device interposed between the sump and the fan as shown in Figure 2. The need for this arises when a number of extract pipes converge on a single fan and must be linked together to form a single pipe which is then connected to the fan.

Referring to Figure 3 a gas-extracting device in the first embodiment of the invention is indicated generally by reference numeral 10. The device 10 is preferably constructed of rigid non bio-degradable material and comprises an enclosed chamber 1 from which a plurality of spigots 2 extend in different directions. At their inner ends, the spigots 2 communicate with the interior of the chamber 1. The spigots 2 are open at their outer ends and are fitted with pipe seals 3 for making a sealed connection to an extension pipe 4. Lengths of perforated pipe 4 are provided and are adapted to fit on to the pipes 2 to engage the pipe seals 3. The seals 3 may be rubber rings as used in drain pipes or other known means for sealing pipe connections. The perforated pipes 4 are perforated along their lengths and at their outer ends are closed with resealable perforated caps 6. One of -6the spigots 2 connects with an extract pipe 7.

In the floor of the chamber a knock-out panel 5 is provided. This panel 5 remains in position on the floor of the chamber and the perforated pipes are not used when the sump is being used as a manifold. In this use, any of the spigots 2 which are not required for use can be capped off and sealed.

When the device 10 is used as a sump, the panel 5 is removed to enable condensation to drain off into the ground. One of the spigots 2 is connected to the extract pipe 7 while the remaining pipe lengths 2 are connected to the perforated pipes 4.

The gas-extracting device in a second embodiment of the invention will now be described with reference to Figures 4 to 8 inclusive.

Referring initially to Figure 4, the gas-venting device in the second embodiment of the invention is indicated generally by reference numeral 20. The device 20 comprises an enclosed chamber 21 from which four spigot arms 22 extend at various directions. The spigot arms 22 extend from the chamber 21, preferably at angles of 60° and 120° to one another and adapted for sealed connection to perforated pipe lengths or to an extract pipe.

With a perforated box type sump of the type disclosed in Irish Patent Specification No. 76310, the suction is exerted equally in all directions (horizontally). However, it is sometimes necessary to discriminate in favour of a particular direction, and this is not possible with the prior art sump. For example with an external sump i.e., a sump placed under floor level immediately outside the external wall of a building, it is necessary to direct the suction so as to extract gas from the interior area, and not to waste the available suction on the exterior air.

With the device in the second embodiment of the present invention, the directional influence can be varied by connecting the extract pipe to a different one of the four arms of the sump, as shown in Figures 5(a), 5(b) and 5(c). -ΊΑ. much more focused effect may be obtained by using standard pipebends of suitable angles of 15°, 30°, 45°, or 90°, between the sump arms and the perforated pipes as shown in Figure 6. As an alternative to using standard pipebends, lengths of flexible pipe could be used.

Furthermore, with the perforated box sump of the prior art the suction can only be exerted at the particular point where the sump is located. In the case of the manifold sump of this invention the suction may be “divided up” and exerted at several points remote from the enclosed chamber as shown in Figure 7.

In certain cases it may be advantageous to close off one of the arms of the sump. In the case illustrated in Figure 8, an external sump is deliberately positioned at a wall separating two adjoining rooms, in an attempt to extract from both compartments.

Capping off one of the arms will increase the suction in the remaining two. The sump in the second embodiment of the invention is obviously more efficient for this type of extraction than the perforated box type sump of the prior art. One particular approach to remedial work in contaminated buildings is to have an extract pipe in each of the rooms leading from a small void under the ground floor to an extract fan in the attic. The pipes have to be manifolded in order to bring a single pipe to the fan. The device in the second embodiment of the present invention can conveniently be used for this purpose, as illustrated in Figure 2 with reference to the first embodiment.

Whereas the device of the present invention has been described above for use with a fan, it will be clear to those skilled in the art that the device could also be used by relying on natural draught (“stack effect”) as in the case of a chimney fire.

It will of course be understood that the invention is not limited to the specific details -8prescribed above which are given by way of example only and that various modifications and alterations are possible without departing from the scope of the invention.

Claims (5)

CLAIMS.

1. A gas-extracting device comprising an enclosed (non-perforated) one-piece moulded chamber having an extract pipe and at least one inlet pipe for providing fluid 5 communication between the interior of the chamber and at least one perforated pipe.

2. A gas-extracting device as claimed in claim 1 having a non-rectangular base and a cover spaced apart from the base, an extract pipe connection means for connecting the chamber to an extract pipe and at least one inlet pipe connection means provided on the side walls, 10 for connection to at least one perforated pipe.

3. A gas-extracting device as claimed in claim 1 comprising a chamber having inlet pipe connection means provided at various acute and obtuse angles from a central section of the chamber.

4. The present invention also provides a method of reducing underfloor pressure in buildings comprising the following steps: Placing a gas-extracting device as claimed in claim 1 in a permeable layer below floor level; connecting the chamber to an extract pipe; connecting perforated elements to the chamber 20 via spigots, sockets, or openings, or additionally via pipe bends and/or pipe lengths, to achieve suction which can be exerted in the vicinity of the chamber, or at a point or points remote from the chamber or which can be aimed in desired directions.

5. A gas-extracting device and a method of reducing underfloor pressure in buildings 25 substantially as herein described with reference to and/or as shown in the accompanying drawings.