GB2461602A - Breather plug for sealed glazing units - Google Patents

Abstract

A circular plastic breather plug for a glazing unit comprising a shaped top and at least two legs "A" having bulbous ends "A1" and a gap between the legs allows airflow from within the glazing unit to the outside. This relieves any pressure build up when the glazing unit is subjected to heat. The shaped top of the plug may be dome shaped and the top may also have a venting channel "B" recessed into its underside surface "C" which is in contact with the glass. Water ingress is prevented by the close fit of the flat underside surface of the breather plug against the glazing material. The hole in the window glazing panel may be drilled retrospectively after manufacture. The glazing unit may comprise a double glazed window.

Description

Breather plug for glazing units This invention relates to a breather plug inserted into the glazing material parts of a glazing unit fitted to residential or commercial building, enabling ventilation to the inside cavity where the unit is comprised of two or more panes of glazing material.

In service, these units are exposed to an almost daily heating and cooling cycle caused by sunlight and building heating systems. This causes repeated pressurisation and de-pressurisation of the air or gas within a sealed glazing unit until eventually the sealing system fails, allowing moisture to enter. At first this is absorbed by desiccant material added to the frame arrangements during manufacture until this material eventually becomes saturated. The first evidence of unit failure is when condensate and fogging is seen on the internal surfaces of the glazing material panes It is known in the art that drilling of a hole or holes into the glazing material panes will ventilate the unit sufficiently. This may be conducted either at failure or pre-failure stage. This method utilises the previously mentioned heating and cooling cycle to force warmer moisture laden air out of the unit through the hole or holes, to be replaced on cooling by drier ambient air, effecting the removal of the excess moisture over a period of time. Exposed holes are however vulnerable to rainwater, cleaning fluids or ingress by insects. There exists in the art a method of affixing over these holes a self-adhesive plastic disc that may contain a filter, or valve, however there are some disadvantages and limitations to these arrangements. (1) Fine internal filters may become clogged with airborne dust and other contaminants. (2) Moving parts within a valve arrangement may fail through wear and tear, materials fatigue and contamination as above. (3) Adhesives have limitations. In winter there can be difficulty getting adequate adhesion on a cold external windowpane. (4) Difficulty in adequately cleaning and drying windowpanes when outdoors. (5) Physical disturbance/damage and accidental dislodgment of adhesive mounted fitments by window cleaning tools. (6) Adhesives may lose their original properties through exposure to weathering, environmental pollution, and UV light. (7) Other designs in the art may propose inserting into the hole(s) a tubular fitment with parallel sides held in place through an interference along it's length. Drilling or boring with hand tools into windows already fitted into a building may make the accurate formation of parallel-sided holes to a set size extremely difficult to achieve. This invention seeks to address these problems in that there is a lesser requirement for exact sizing of holes. A tolerance for reasonable variations in hole size and shape exists within this invention. The legs inserted into the glazing material will accommodate holes that are not exactly to size, not exactly at 9Odegrees to the glazing material surface, or not parallel sided.

Breather plugs of different sizes can also be used to accommodate bigger variations in hole sizes or glazing material thickness.

This invention proposes that having drilled or bored a small hole or holes through one of the glazing material panes, there is inserted into the hole or holes a dome headed breather plug containing a channel which will form an internal airway when the breather plug is in it's fitted position This will allow adequate airflow, while preventing excessive air volumes from passing in and out of the glazed unit. During wet weather and normal washing routines, water cannot enter the glazed unit cavity as in its fitted position the flat underside face of the breather plug is located against the glazing material surface, additionally during fitment the breather is positioned so as to ensure that the opening to the airway is facing downwards. Insect entry is minimised by the size of the opening.

The invention will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 shows the breather plug before installation.

Figure 2 shows the breather plug inserted into the glazing unit, side view Figure 3 shows the breather plug inserted into the glazing unit, view from underside Figure 3a shows the breather plug as seen fitted in plan view.

In figure 1 the breather plug is shown before installation. The breather plug is a one-piece moulding in a suitable plastic material. It has a slightly domed outer part to resist disturbance or damage.

The two legs A and Al are arranged to project into the hole formed in the glazing material. A suitable gap between the legs allows for airflow into the window. The legs are designed to spring slightly towards each other as their bulbous shaped ends pass through the hole in the glazing material.

Channel B is formed in surface C. This runs between the gap already existing between the legs A and Al and the perimeter of surface C creating a link between the legs and the outside air. This allows the breather be rotated before insertion to a position which prevent unwanted materials and/or water ingress.

In figure 2 the breather plug is shown inserted into a glazing unit, viewed from the left hand side.

The gap between the legs cannot be seen in this drawing because it is aligned vertically to enable the external end of channel B to face downwards. It is a feature of the legs that their width is slightly smaller across their top to bottom section to maintain a gap should the ends be closed completely when inserted in holes which are slightly undersize. (This can be better seen when comparing Fig 2 with Fig 3 and noting the differing space between the legs the sides of the hole) The flat surface C sits flush against surface of the glazing material. This exploits the surface tension and molecular attraction characteristics of water that may have migrated between them, preventing it from exiting the area under surface C and entering the hole. Air can flow around and between these legs to enter and leave the cavity. This process is driven by the thermal expansion and contraction of the air within the window cavity resulting from solar and building heat. When no such process is at work an equal pressure inside and outside the unit is maintained ensuring little or no air movement. The cross section and size of the aperture B is not critical to the performance of the breather plug, but is sized to reduce any unnecessary airflow which could compromise the insulation properties of the unit, as well as reduce the ingress of unwanted materials. The slightly domed top or outer edge of the breather plug will deflect any objects striking or rubbing this area, such as cleaning cloths, window cleaners wiping blades etc. Removal by anyone especially children is made difficult unless tools are used to prise the breather plug out of the hole.

In figure 3 the breather plug can be seen in cross section from underneath. The legs are wider in this view as mentioned above. The breather plug is being held in place by the bulbs on the ends of the legs. When they are pushed through fully their entry into the cavity results in them assuming their original positions. It can be seen that the length of the parallel sides of the legs is slightly less than the glazing material thickness, this ensures that the inside edge of the hole sits on the start of the tapered ends of the legs, these are now slightly larger than the hole diameter.

Because they are not fully through into the cavity they exert a slight inward force on the breather plug to ensure continued contact between surface C and the glazing material. Removal will require sufficient outward force to spring the legs inwards in order for them to pass back through the hole.

Where glazing material of a greater thickness is encountered, the legs will be unable to reach through into the cavity, they will however remain in the hole being compressed slightly, in this case the friction of the legs against the inside surface of the hole will be sufficient to hold the breather plug in place, alternatively a breather plug with a suitably longer leg length can be used to achieve the fitment method shown in Fig 3 The small additional plan view Fig 3a shows the breather plug as seen in position in the glazing material from the outside.