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V

Valve. A mechanical contrivance used for controlling or shutting off the passage of air, steam, water, etc., into or out of a boiler, cylinder, tank, compartment; or through a pipe line.

Valve, Air. Any valve on a compressed air line. Also used in reference to the control mechanism on front of a boiler for regulating the supply of forced draft to the boilers.

Valve, Alarm. Any valve which automatically gives an alarm. Sometimes it used in a fuel tank to indicate when the tank is full and consists of a float valve with electric contacts. Also used as a small safety valve on a boiler, where it is set to open at a pressure of 5 or 10 lbs. below the regular safety valves, thus giving warning of the approach of the maximum allowable pressure.

Valve, Angle. A valve with a spherical shaped body having a screwed or flanged inlet at the bottom and a screwed or flanged outlet at the side. A circular valve, fitting snugly on a circular seat, is actuated by a valve stem or rod having a screw thread cut on it which engages in a thread cut in the bonnet or cover. The valve stem is turned by means of a hand wheel.

Valve, Balanced Whistle. See Whistle Valve, Balanced.

Valve, Blow-Off. A valve for discharging the contents of a boiler, evaporator or other container. Valves are used to discharge from the surface of the water in the boiler and also from the bottom.

Valve, Brass Mounted. A term applied to a valve where such parts as the disc and ring, stem, seat and bonnet are made of brass.

Valve, Butterfly. A valve in which a disc revolves on a diametrical axis similar to a damper. Also applied to a valve in which two semi-discs are hinged on a diametrical axis so that they both open and close similar in manner to the wings of a butterfly.

Valve, By-Pass. A small valve used on a larger valve for the purpose of by-passing the pressure from one side to the other of the larger valve so that it will open easily.

Valve, Check. A valve so arranged as to permit flow in one direction only. Usually it consists of a valve disc carried from a hinged support and hanging at an angle of about 45°, or it may be of the ordinary type of valve without valve stem and fitted with a spring to insure rapidity of closing.

Valve, Check, Boiler Feed. A screw down, non-return valve, installed in the pipe lines between the main and auxiliary feed pump and the boilers. Its object is to prevent the water in the boiler from backing up through the feed lines between strokes or when the pump has stopped or broken down.

Valve, Cross. A term applied to a valve fitted on a by-pass between two lines of piping, thus providing communication between them. It is usually an angle valve with two side outlets.

Valve, Delivery. Usually refers to the main outboard delivery valve controlling the discharge of water from the condenser to the sea.

Valve, Engine-Room Control. The main stop valve on the steam line to the main engines controlling the supply of steam to the engines and located in the engine room.

Valve, Escape. A valve on a steam engine or boiler intended for the relief of excessive pressure and for the escape of steam.

Valve, Flap or Storm. A simple form of check valve at the bottom of a scupper pipe which permits water to discharge from the scupper overboard but prevents sea water from backing up the pipe.

Valve Gate. A valve with an inlet on one side and an outlet directly opposite on the other side. The gate consists of a nearly flat tapered disc which slides in a groove that is perpendicular to the passage through the valve. When open the gate is drawn up into a slot in the bonnet of the valve leaving the passage clear. The valve stem is threaded and is worked by a hand wheel. The distance from face to face of the inlet and outlet flanges or connections is much less than in a globe valve.

Valve, Globe. A valve with a spherical shaped body having a screwed or flanged side inlet and outlet. A circular valve fitting snugly on a circular seat, is actuated by a valve stem or rod having a screw thread cut on it which engages in a thread cut in the bonnet or cover. The valve stem is turned by means of a hand wheel. Globe valves are strong, compact, and tight. When fitted, care should be taken to set them so that they will close against the pressure, otherwise they can not be opened if the valve stem is broken or becomes detached.

Valve, Kingston. A sea valve so arranged that the pressure of the sea forces the valve in its seat or closes it, thus differing from most valves which are so arranged that the pressure is in the direction of opening of the valve.

Valve, Main Check. Check valves located in the feed water discharge pipes at or near the boiler.

Valve, Maneuvering. The term applied to valves used to vary the speed in turbines.

Valve, Needle. A valve which controls the flow of a gas or liquid by a long tapered point, permitting extremely fine adjustments of the flow.

Valve, Non-Return. A type of check valve with a swinging valve disc.

Valve, Outboard Delivery. See Sea Chest.

Valve, Pet. A small valve used in the regulation of pump action by means of regulation of an air supply.

Valve, Piston. A steam valve consisting essentially of two pistons, one to each port, connected by a rod or spindle. The steam enters round the outer edges of the pistons and exhausts past the inner edges or vice versa. The steam ports and passages are cast in the cylindrical chamber in which the piston valves move. Thus the piston valve is perfectly balanced in so far as the steam pressure is concerned and the frictional load induced by the excess steam pressure on the back of the ordinary slide valve is eliminated, there remaining only such frictional resistance as is necessary to obtain tightness against steam leaks.

Valve, Poppet. See Valve, Throttle.

Valve Quadrant. That portion of the reversing gear on a steam engine to which the ends of the eccentric rods are attached and which is curved to the arc of a circle.

Valve, Radiator. A valve controlling the flow of hot water or steam to a radiator. It is usually an angle valve.

Valve, Reducing. It is located in the steam supply line in order to reduce the pressure of the steam supplied to auxiliaries. Such reductions are made in the interest of production economy and steadiness of operation.

Valve, Reducing Steam. A self-acting valve so arranged by means of diaphragms and springs that the steam pressure will be reduced after passing through the valve.

Valve, Regulator. A valve so constructed that it will deliver a liquid or a gas at a given pressure.

Valve, Relief. A valve designed to open automatically at a desired pressure. They are installed on the cylinders of reciprocating engines and sometimes on the valve casings.

Valves, Safety. Valves arranged to open at any predetermined pressure and, by permitting the escape of vapor, gas or other medium, to prevent explosion or damage to the boiler, tank or other container.

Valve, Sea. A valve located at or near the outside plating of a vessel to supply sea water to the fire pumps and for flooding the ballast tanks, etc.; also for discharging water overboard from bilge pumps, ballast pumps, condenser circulating pumps, boiler blows, etc.

Valve, Sea Suction. See Sea Chest.

Valve, Sentinel. See Valve, Alarm.

Valve, Shifting. A small sized valve placed on condensers, pipes or, in general, other low pressure parts to allow the escape of air trapped in pockets, the valve closing automatically to prevent inflow from the atmosphere.

Valve, Slide. A device intended to regulate the admission of steam to and its exhaust from the cylinder of a reciprocating engine. For this purpose it is given a straight line reciprocating motion bearing a definite relation to the piston itself. This relation is such that the steam ports in opposite ends of the cylinder are alternately uncovered so that steam is admitted first to one side of the piston and then to the other at the proper points in its stroke, the exhaust taking place regularly meanwhile. The operation of the engine then becomes continuous.

Valve, Sluice. A valve secured to a bulkhead usually without any connecting pipes, for use in allowing water to flow to and from adjoining compartments.

Valve Stem. The rod connecting the valve with its means of motion, in the case of a steam engine with the eccentric and rod, and in the case of a water valve with the hand wheel.

Valve Stem Guide Bracket. The bracket forming a guide support for the outboard end of the valve-stem, some distance away from the valve chest, and intended to keep the valve stem in straight line motion.

Valve-Stem Stuffing Box. The box on the end of a valve, through which the valve-stem travels, containing the packing, which prevents the escape of a gas or fluid under pressure from the valve. The stuffing box generally consists of an enlargement in the valve for the reception of the packing and a gland for pressing the same into place against the rod.

Valves, Stop. Generally considered as the valves especially fitted to cut off the supply of steam from the boilers to the engines. Also designated to distinguish from check valve, stop check valve, stop check lift valve, etc. Stop valves are fitted in pipe lines where it is desired to permit flow or to shut off the flow, the check valve being intended to permit flow in one direction only, the stop check acting as a stop valve in shutting off flow and also a check, but limiting the flow at all times to one direction, while the stop check lift serves as a stop valve, may act as a check valve, and may, if desired, permit flow in both directions.

Valve, Stop, Boiler. A valve installed on the line connecting each boiler with the main steam line. By this valve any boiler may be cut off completely or the steam from it regulated.

Valve, Storm. A simple form of check valve or flap valve on the end of a pipe discharging through the ship’s side above the waterline to prevent the sea from backing into the pipe.

Valve, Throttle. A valve designed to control the supply of steam to the engine when stopping and starting. It is fitted in the main steam pipe near its point of connection to the high pressure valve chest. The principal requirements to be met are rapidity of operation and minimum obstruction to the flow of steam when open.

Valve or Steam Chest, sometimes termed Valve Box. The casting in which steam passages and ports are formed and through which the rod which actuates the valve works. It is provided with covers for access and inspection, is fitted with a stuffing box through which works the valve rod and with openings for the attachment of the main steam pipe from the boiler as well as for the exhaust steam pipe to the open air or condenser.

Valves, Under-water. Valves such as sea valves which can only be repaired or replaced while the ship is in dry dock.

Valves and Cocks, Sluice. Sluice valves and cocks may only be fitted on watertight bulkheads under conditions where they are at all times accessible for examination; the control rods are to be workable from the bulkhead deck, and are to be provided with an index to show whether the valve or cock is open or shut, the control rods are to be properly protected from injury, and their weight is not to be supported by the valve or cock. No sluice valve or cock is to be fitted on a collision bulkhead.

Vane. A fly made of bunting and carried at the truck, which being free to rotate on a spindle, indicates the direction of the wind.

Vangs. Ropes secured, generally one on each side, to the outer end of a cargo boom, the lower ends being fastened to tackles secured to the deck. The vangs are used for guiding and swinging the boom and for holding it in a desired position, as over a cargo hatch. The term is also applied to ropes secured to the after end of a gaff and led to each side of a vessel in order to steady the gaff when the sail is not

Veer-Chain. A command to allow the anchor chain to run out.

Veering. Changing direction, used in referring to the wind and also to the course of a vessel.

Veneer Press. A press designed to hold or clamp a thin layer of high class or expensive wood on a backing of inferior grades of wood until the glue uniting the two is hard and set.

Veneering. The art of facing inferior grades of soft wood with a thin layer of more expensive hard wood.

Ventilating Flooring. See Gratings.

Ventilating Trunk. See Trunck, Ventilating.

Ventilating System. A system consisting of light metal pipes, blowers, special intakes, etc., for supply of fresh air to and removing foul air from the various compartments in a vessel.

Ventilation. The process of providing fresh air to the various spaces and replacing foul or heated air by fresh air.

Ventilation, Mechanical. Ventilation supplied by fans or blowers and sometimes by compressed air, the fans being operated by electric motors, steam engines or other mechanical means. The ventilation in this case is forced or induced by the fan through a pipe or pipes to one or more compartments whereas natural ventilation would require a separate pipe and cowl for each compartment.

Ventilation, Natural. Ventilation depending on the wind blowing into the cowls and down the ventilators, and also on the natural tendency of heated air to rise and escape through the pipes and trunks provided.

Ventilation, "Thermotank" System. A ventilation system in which the air is heated by passing over or around tubes through which steam or hot water is circulated. The box or tank containing the steam coils is called the Thermotank.

Ventilator, Mushroom. See Mushroom Ventilator.

Ventilator Turning Gear. Simple form of rack and pinion with hand wheel and shafting arranged so that the ventilator of the cowl type located on an open deck can he turned so as to face the wind of a supply ventilator, and away from the wind if an exhaust ventilator.

Ventilators, Bell-Mouthed or Cowl. Terminals on open decks in the form of a 90 degree elbow with enlarged or bell shaped openings, so formed as to obtain an increase of air supply when facing the wind and to increase the velocity of air down the ventilation pipe.

Ventilators, Goose-Neck or Swan-Neck. Terminals consisting of a 180 degree bend used only on ends of exhaust pipes and so shaped as to make the clogging of the outlet difficult.

Vertical Borer. A vertical spindle drilling machine used for drilling holes in wood.

Vertical Center Keelson. See Keelson, Vertical.

Vessel. A craft designed to float on and pass from place to place over the water. The term usually refers to types larger than boats.

Vessel, Sailing. A vessel propelled by sails. Where there is an auxiliary power plant she is only a sailing vessel as far as the navigating laws are concerned when the machinery is not in operation or when she is not under steam.

Vessel, Steam. A vessel propelled by steam power. According to the rules to prevent collisions in the navigation laws, all vessels over sixty-five feet in length propelled by machinery and tugboats and towboats of any length propelled by steam are considered steam vessels. If both machinery and sails are installed, she is considered a sailing vessel only when not under steam.

Virtual Center of Gravity. The point at which the weight of a liquid with a free surface may be considered to be concentrated when taking account of its effect upon the initial stability of a vessel. The virtual center of gravity of a free liquid is in a vertical line directly above the actual center of gravity and the distance between the actual and virtual centers of gravity equals the moment of inertia of the free surface divided by the volume of the liquid.

Vise, Combination. A type of vise designed for securely holding work of irregular form while filing, etc.

Vise, Hinged Pipe. A type of vise especially designed for use on pipe works. It is usually mounted on a work bench or table and the frame is made in two parts hinged on one side and locked with a toggle pin on the other. The upper jaw is operated in a vertical direction by a threaded spindle passing through the upper frame. The jaws are made in a diamond shape to give a better grip on the pipe.

Visor. A small inclined awning supported by a pipe frame running around the pilot house of a steamer, over the windows, to exclude the glare of the sun or prevent rain from coming in over the tops of the window sashes.

Voice Tube. A tube designed for the carriage of the human voice from one part of or station in the ship to another.

Volt. The practical unit of electromotive force. It represents that pressure which produces a current of ampere in a resistance of 1 ohm.

Voltage Regulators. An instrument usually mounted on a switchboard for the purpose of keeping the voltage at a predetermined value.

Voltmeter. An instrument for measuring the difference in potential between two points in a circuit.

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