This article throws light upon the three main types of doors that eliminate all paths of noise. The types are: 1. Hinged Doors 2. Door Furniture 3. Sliding Doors.
Type # 1. Hinged Doors:
The simplest and cheapest solution is provided by hinged doors; but they should be acoustically insulated, and should achieve an airtight seal when closed. There is a wide variety of designs available for hinged doors. The performance characteristics of these are specified by the manufacturers. Proprietary designs provide the usual answer to openings of “standard” size (not exceeding one metre).
One possible disadvantage of hinged doors is that they require floor space for opening. This problem may be solved by swinging the hinged doors back against the wall; but then wall and floor space both are lost. Double-hinged doors are designed to reduce the size of the opening circle and also to lighten the weight on the hinges.
The requirement of sound insulation tends to make the doors very heavy. With larger hinged doors, therefore, additional problems may arise. For example, if the hinges are too light, the doors may sag and drag on the floor.
In the case of double-hinged doors, sealing gaskets have to be fitted to the outer edges. This, however, makes them vulnerable to damage if goods are being moved through these larger openings. On the other hand, sealing the bottom of hinged doors requires a raised sill to be fitted to the floor so that the bottom gasket fits the sill in the same way as the top.
The raised sill, however, can be a nuisance when goods are to be moved in or out, since the sill has to be negotiated each time. Sometimes, the raised sill is eliminated by fitting the so-called “rising” hinges. These hinges operate in such a way that the door rises from the floor when it is opened. In this way, the bottom gaskets are spared much wear and tear.
In this connection, the hinged doors to be avoided are those fitted with normal hinges and a very flexible “sweeper” gasket of rubber on the bottom. Such doors open and close with difficulty due to the friction of the rubber gasket on the floor. After a while, the friction will certainly disappear; but so will the rubber gasket.
Hinged doors can be advantageous in acoustic enclosures, provided they are used for pedestrians and do not exceed a width of one metre. In the case of narrow corridors, 180° open doors are preferable. If raised sill is not acceptable, doors with “rising” hinges should be chosen. Double-hinged doors may not always be desirable, since the seal in the middle may prove to be unreliable.
Type # 2. Door Furniture:
There are many factors hitch affect the design and selection of suitable door hinges and fasteners. In the first place, the most vulnerable parts of an acoustic enclosure (for the leakage of noise) are the places where joints and apertures appear. It follows, therefore, that unless these apertures are treated with the same degree of care and expertise as the rest of the enclosure, the final results will not be as planned.
Some of these apertures will, of course, be doors. The sound reduction index of the door may be the same as that of the rest of the enclosure; but the acoustic results actually obtained depend almost entirely on the effectiveness of the seal between the door and the door frame.
In order to achieve a satisfactory’ seal, it is necessary to ensure that the method of retaining the door in the frame as well as the method of construction are both compatible and efficient.
To retain the door, it is usual (but not essential) to use a door fastening device (or devices) on one side of the door and hinges on the other. Thus the hinges are not just a means of swinging the door open; they also play an important role when the door is closed. Unless hinges of proper design and tolerances are fitted to the frame and door with similar accuracy, the required seal will not be achieved.
Type # 3. Sliding Doors:
Sliding doors can prove advantageous when openings wider than 1-2 metres have to be closed, provided sufficient sliding space is available. Moreover, sliding doors also offer a more flexible choice, since they can slide either to the right or to the left, and can be fitted on the inside or the outside of the opening.
In spite of these advantages, sliding doors have their own inevitable limitations. For example, sliding doors are more expensive because of the more complicated structure needed for them.
On the other hand, sliding doors can be located in almost any opening; but this requires some careful planning. However, specialist door manufacturers are equipped to deal with problems of limited space. They may even have solved the same or very similar problem for another customer.