A galvanized steel line from the exhaust gas elbow between the inner and outer exhuast valves leads to the main ballast tank blow manifold and snorkel mast. A cutout valve is installed on the line where it leaves the elbow. The port and starboard lines are joined before they reach the main blow manifold. The line to the snorkel mast is connected to this common line; a stop valve is installed to permit securing the exhaust to the snorkel when is mot in use.

The exhuast valves , thee piping between them and the waterjacket on the inboard valve are tested at 284 psi. The exhaust line between the exhaust elbow and snorkel mast exhaust valve and main blow manifold is tested at 142 pis for tightness ans 213 psi for strength. The exhaust piping and fitting aft of the outboard exhaust valve, and all external circulating water piping and water jackets are tested at 28.4 psi.

The inboard exhaust valve is made up in two sections. The lower section contains the valve seat and disc. The upper section acts as a housing for the valve disc when the valve is open. The valve operates on a counter weighted hinged principle; a lever that is keyed to the hinged shaft is used to open and close the valve. Provision is made fro rotating the valve disc on its seat, the rotation serving to clean the carbon from the seat and to provide a slight amount of grainding in. The worm keyed to an inner hinge shaft meshes with the geared periphery of the valve disc. A ratchet arrangement on the same hinge shaft provides the means for giving the circular rotation to the disc. A special tightening arrangement is also provided for the valve when it is in the closed position. Leverage is applied to a bell crank, that is keyed to the outer hinged shaft, through a hand wheel and its threaded shaft.

The outboard exhaust valve also works on the hinged principle and has a similar grinding in arrangement. The main difference between the two valves lies only in the method of transmitting the motion to them for opening and closing as well as for rotating. The outboard valve is opened by a handwheel that transmits its rotation through a gear and crank arrangement to the hinged shaft of the disc. Tighting of the valve on its seat is accomplished directly by the handwheel in this case. When the valve is opened the disc is housed in a recess. In lieu of a ratched arrangement to provide rotation to the disc a handwheel arrangement is used. The handwheel is geared directly to the inner hinged shaft on which the worm that rotates the disc is located. A spring is attached to the hinged shaft to take the weight of the disc when it is being closed.

All cutout valves in the exhaust line with the exception of those in the main blow manifold have provision for rotation of the valve disc on its seat. It is accomplished on the smaller valves by an inner shaft that is keyed to the valve disc and which passes through the center of the valve handwheel. Small drain and vent valves as well as the direct exhaust valves have this feathure.

A dry type muffler was designed for installation on the Type IXC and IXD2 vessels. The muffler is built in two circular sections. The inner section consists od three separate cylinders spaced longitudally and joined by small radial fins. The outer section is the muffler shell proper and its waterjacket. In cross section the inner cylinder and shell form concentric circles with approximately equal gas volumes within the inner and outer gas space. Zincs are installed to reduce corrosion of the muffler.

All expansion in the exhaust piping, both before and after the muffler, is taken up in the muffler. The foundation for the latter is rigidly attached to the outer waterjacket. Expansion between the waterjacket, muffler shell and inner inserted cylinders is provided at the after end by a packing gland, and between the inner and outer shell by another gland at the forward end. Packing glands are also provided at the forward and after ends of the muffler where the main exhaust piping leads into it. Means for ready flooding on diving and for venting and draining the waterjackets is also provided.

The exhaust damper is installed primarily for use when blowing ballast tanks. It permits a ready regulation of both the volume and pressure of the exhaust gases that pass to the blow manifold and thus minimizes the variation necessary in engine out put. Without the damper, wire drawing through one of the main exhaust valves would be necessary which would in turn, soon ruin the seat. The damper is controlled by a handwheel in the engine room which imparts rotary motion to it through a gearing and crank arrangement.

The spark arrestor is a simple device for causing the sparks in the exhaust to be deposited in a pool of water Circular baffles direct the gases entering the arrestor into the bottom of the large casing in which the water level is kept essentially constant. Baffles on the outboard side of the arrestor direct the gas flow over the side.

Two inboard grease manifolds are nstalled for use with the operating gear in the exaust gas system. One manifold services all bearings, gears, shafts etc. forward of the mufflers and the other services those parts aft of the muffler. The piping and fittings are tested to 284 psi. There you have it.