Several patterns of radiator valves are shown in Figs. 50, 51, 52, and 53. These valves are of brass or composition, rough body nickel-plated, have wood wheels, and are provided with a union. The angle valves are commonly used on first-floor radiators, those on floors above having offset or corner offset, offset globe, or straightway gate valves, according to the type of radiator and the arrangement of con nections to provide for expansion.
In public buildings, the wheels are often omitted and lock-shields substituted, the valves being operated by a key.
A valve is shown in Fig. 54. This type, if prop..
erly designed, works the easiest of any, and should be used in prefer ence to other types when radiators are placed but little above the water line in the boiler.
Air-Valves. Numerous patterns of air-valves are on the market, some, like Fig. 55, in a general way, being fitted with a union for air line connections leading to a convenient point of discharge in the base ment. Such valves prevent the escape of steam, because of the ex pansion of the composition plug, which closes the opening when steam comes in contact with it. Air and cold water, however, are permitted to escape.
The general type of air-valve shown in Fig. 56 is frequently used, many modifications of this valve having been manufactured. These valves, as a rule, have no air-line connections, but discharge their air into the rooms; a somewhat objectionable feature. They close when steam enters them; and if water finds its way in, the float is raised and closes the outlet.
Air-valves for direct radiators have a very small opening for the discharge of air, scarcely larger than a pin-hole; and while these do very well for small units, they are not satisfactory for large coils or for large groups of indirect radiators, because of the excessive time re quired to relieve them from air. For such heating surfaces, a type of air-valve with a much larger opening should be selected, to provide for venting the radiators or coils more quickly.
Several types of vacuum air-valves have been invented, designed to permit the escape of air from the radiators, but to prevent its re entry. If they remain tight, the steam heating system may be run in mild weather with a pres sure below that of the at mosphere, and the radiator kept at a temperature be low 200°.
Pipe-Fitting Tools.— Vise and Bench. When a job is started, the first things needed are vise and bench. The latter should be firmly constructed, and rigidly held in place, the vise to be firmly secured to it by through bolts.
On a good-sized piece of work, it is well to have both a pipe vise and a flat jaw vise, these being illus trated in Figs. 57 and 58. A heavy cover should be furnished over the screw of the flat-law vise, to provide a bearing for bending pipe, the end of which is passed through a ring bolted to the bench.
Fig. 59 illustrates a combination of the two vises shown in Figs. 57 and 58, making a very useful tool.
Pipe Cutters. There are several kinds of pipe cutters on the market, made with one or more cutting wheels held in a frame. All makes of cutters are operated in practically the same way, by forcing the cutting wheels into the pipe by means of a screw handle. One- and three-wheel cutters are shown in Figs. 60 and 61. The one-wheel cutters are made in sizes for finch to 3-inch pipe; and the three wheel cutters, for finch to 8-inch pipe.
Stocks and Dies. The several forms of dies and stocks on the market may be divided into two classes—the solid die and the adjustable die. The solid die is shown in Fig. 62, and is used for cutting both right hand and left-hand threads. The stock in which solid dies are used is shown in Fig. 63. Adjustable dies and stocks are shown in Figs. 64 and 65. These dies may be adjusted to cut a deep or a shallow thread. It is necessary at times to cut such threads, as the fittings made by different manufac turers are not always tapped alike. To make good joints, the threads must make up tight when they are screwed into the fitting.
Table IX shows the ap proximate distance pipes must be screwed into fittings to make a tight joint.
In all forms of stocks, whether for solid or adjustable dies, a bushing or guide must be used in the stocks to guide the dies straight onto the pipe. It is necessary that the guides for the different sizes of pipe should fit each size of pipe as closely as will allow the guide to revolve on the pipe freely. The guides should fit the stock as tightly as possible, or a crooked thread will very likely be cut.