Generac 00784-2, 09290-4 Acoustics, Sound Insulating Materials, 6 - Types of Lock Seams

Section 2 – Installation

PRIMEPACT 50 and 70 (50Hz) Recreational Vehicle Generators

•If flexible metal conduit is used, it must be sealed internally at the end where it terminates inside the compartment’s electrical junction box.

NOTE:

Flexible metal conduit, due to its unique con- struction, is NOT vapor tight along its entire length.

•Seams and joints of the galvanized steel (whether used as a liner or for the compartment itself) must be lapped and mechanically secured. Such seams may be manufactured, welded, bolted, riveted or screwed. Manufactured lock seams are shown in Figure 2.6. Installer constructed compartments typically utilize a standard lap joint.

Figure 2.6 – Types of Lock Seams

Do not install sound insulation or any absorbent material on the compartment floor interior. Such materials will become soaked with combustible or explosive vapors and liq- uids and will become a fire hazard.

Using a combination of sound insulating materials can often reduce noise more effectively than a single material. For example, a sheet of lead or visco-elastic material, along with a layer of other acoustical mate- rial, is more effective than when a single material is used.

◆2.2.4 ACOUSTICS

For additional noise abatement, the installer may wish to consider the following:

•Using special sound insulating materials.

•Construction of a special noise abatement compartment.

NOTE:

•After the compartment has been metal lined and vapor sealed, line the compartment interior walls and ceiling with an approved, nonflammable sound insulating material. See Section 2.2.3.

Do not install any flammable material directly above or around the compartment. Heat, transferred through the compartment structure, may be sufficient to ignite, char or discolor seat cushions, fiberboard and other flammable materials. You may need to use approved nonflammable insulating materials in high temperature areas.

◆2.2.3 SOUND INSULATING MATERIALS

Once installers have determined that a compartment is properly constructed and metal lined, they can add acoustical material. This may include additional sealant or insulating material, to reflect noise away from the vehicle interior.

Sound insulating materials should be of a nonflam- mable type. One excellent insulating material is a 1- inch (25 mm) thick fiberglass having a 2-pound den- sity. When fiberglass is used, its coated side should face toward the compartment interior.

Any method used to reduce noise must not adversely affect the flow of cooling and ventilating air into or out of the compartment.

In addition to the effective use of sound insulating materials, construction of a special noise abatement compartment might be considered to reduce noise levels. Such a compartment might be constructed as follows (Figure 2.7):

•Use 5/8-inch thick or 3/4-inch thick plywood in the compartment.

•Construct the compartment floor of a double thick- ness of 5/8-inch or 3/4-inch plywood.

•Line the compartment interior walls and floor, as well as the underside of the floor, with 26-gauge galvanized steel.

•Vapor seal all compartment seams and joints.

•Over the galvanized steel lining, install a combina- tion of acoustical materials as mentioned in Section 2.2.3.

To prevent fire or explosion, do not install any insulation or other absorbent materials on the interior or underside of the compartment floor.

•Seal all compartment door edges to prevent noise leakage around the door perimeter.

•Line the compartment door interior (except for air openings) with suitable, fireproof sound insulation (such as 1-inch (25 mm) thick fiberglass with a 2- pound density).

24 Generac® Power Systems, Inc.