To prevent unsatisfactory performance due to piping resonance or shock waves that can develop in the piping between the engine and the silencer, it is recommended that the silencer be installed as close as possible to the engine. The exhaust pipe length between engine and silencer should not exceed fifteen times the silencer size. For example, a 6” silencer should be installed within seven and one-half feet (90”) of the engine. If the above recommendation can not be followed, the customer should discuss the installation with Maxim.

For most exhaust systems designs, it is necessary that an expansion joint be installed between the engine and the silencer. This will allow thermal expansion as well as reduce the amount of engine vibration transmitted to the silencer. If a short exhaust system with no expansion joint is desired and the silencer is to be supported directly on the engine flange, the silencer inlet should be provided with gussets.

It is imperative that the exhaust gas flow in the correct direction. All silencers are equipped with nameplates that show the correct flow direction.

On spark arrestor silencers, the silencer body is equipped with a box on the side that acts as spark trap. If the silencer is mounted horizontally, the spark trap should be on the underside. If the silencer is mounted vertically, the orientation of the spark trap is discretionary. The purpose of the couplings on the spark trap is to provide access for cleaning purposes.

The silencer may be supported by the inlet and outlet flanges, provided the piping on both ends of the silencer is equipped with lateral supports or guides to prevent large bending moments from being transmitted to the silencer flanges. The following flange loadings are the maximum permissible for most installations. Do not load beyond these limits: Axial (in a direction parallel to the nozzle axis): A force equal to the silencer weight. Shear (in a direction perpendicular to the nozzle axis): A for equal to the silencer weight. Bending Moment: The silencer weight multiplied by the silencer size. For example, a 12” M-51 which weighs 1,295 lbs. can withstand the following nozzle loads: axial: 1,295 lbs., shear: 1,295 lbs., bending moment: 15,540 inch-lbs. Contact Maxim for additional loading information.

For those installations where the silencer is to be supported by the inlet only, the user should install four stiffener gussets on the inlet nozzle. These gussets should be welded to the flange, the nozzle and to the silencer end head. A special silencer with factory installed gussets may be ordered if desired. Likewise, if the silencer outlet is to support a long tailpipe with no lateral support, the outlet nozzle of the silencer should have gussets. A tailpipe of maximum length equal to six times the silencer size may be supported free standing without gussets. For example, a 12” silencer without gussets can support a 72” long free standing tailpipe.

For horizontal silencer installations, the silencer may be supported by factory installed saddles or bracket supports. However, the user may choose to support the silencer with two body bands, which are attached to overhead hanger rods. For vertical silencer installations, the silencer may be supported by factory installed legs, trunnions, or bracket supports.

It is recommended that a silencer never be connected to more than one engine at a time.

Design of the exhaust system must be such that water is not allowed to flow back into the engine. Silencers are not specifically designed to prevent the flow of water back into the engine. With some configurations, the silencer body may become a water trap and for this reason, drain couplings are provided on some models. However, the presence of a drain coupling does not mean that the silencer will prevent water from flowing back into the engine.

A typical engine exhaust system has gas temperatures between 500°F and 1,200° F. A typical uninsulated silencer will have an outside skin temperature between 400° F and 900° F. An approximate value for the amount of heat transmitted through the silencer walls is 2.0 BTU per hour per square foot of surface area per °F difference between the gas temperature and the outside air temperature. In view of the above considerations, the user often elects to insulate the silencer body to either reduce the external skin temperature or to reduce the amount of heat transmittal. However, insulating the silencer body will mean that the silencer shell temperature will be almost as hot as the gas temperature. Since carbon steel scales and deteriorates very rapidly when its temperature exceeds 1,000° F, the user must be aware of the possible consequences of insulating a silencer that operates with gas temperatures above 1,000° F. Stainless steel construction is advised under these circumstances. If burn protection of personnel is the main reason for insulating, the user should use an expanded metal safety shield rather than insulation.

Unless specified in the customers purchase requirements, a silencer is not pressure tested. If it is mandatory that absolutely no leakage is to be permitted, the silencer should be purchased with specifications requiring pressure testing at the factory.