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In the selection of material entering into the construction thereof, great care has been taken to provide metals of uniform texture, of great strength, and of kinds best adapted for service imposed, and without regard to cost. For the maximum pressure, second, third, and fourth stage air cylinders are provided, with inter-coolers of very liberal cooling surfaces, and an after-cooler. The main bearings are automatically lubricated, the oil pump therefor being actuated by a reciprocating part of the machine and a device provided for automatically cooling and screening the lubricant. A cooling water pump is also attached, providing circulating water for air cylinders and inter-coolers.

Air valves are of special design permitting of the speed mentioned above, and quiet operation. Special lubricators are provided.

AIR COMPRESSOR GOVERNOR

Where a steam driven single air compressor, or a compressor driven by a constant speed motor, is used to furnish air in varying quantities, some method other than the extremely wasteful one of allowing the surplus air to escape through a safety valve should be used. By preventing the atmosphere from entering the cylinder the compressor cannot do any work, consequently cannot consume power, although running at full speed, beyond that required to keep the machine alive, or rather to overcome the unloaded frictional resistance. An automatic valve for accomplishing this is shown in cut. It is simply a balanced governor valve controlled by a pilot valve. A small pipe leads from the air receiver to the pilot valve. The weight or spring, or both, may be

regulated to allow the valve to unload at any pressure desired. With a slight fall in the receiver pressure it will gradually allow the air to enter the cylinder, thereby giving the compressor its load again.

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This device loads and unloads very gradually, giving the compressor time to receive its load without shock; is noiseless in its operation, and is very close in its regulation.

DIRECTIONS FOR SETTING AND OPERATING

AIR COMPRESSORS

FOUNDATION. It should be the first care in installing an Air Compressor to provide it with a suitable foundation. The Compressors are self-contained and need foundations only of such design and strength as will insure the compressor remaining rigidly in place, a poor foundation costs almost as much as a good one, and as a compressor is usually a permanent fixture, it is advisable to put in a good foundation.

Blue prints are usually furnished showing location and proper size of foundation bolts for each machine, from which a template can be made by which the foundation. bolts can be accurately located. It is of great importance that space should be left around foundation bolts so that they may be left free to move. The setting of the compressor is rendered much easier by taking this precaution. A good way to do is to put a short piece of pipe around each foundation bolt, carrying it up with the foundation, thus leaving the desired space behind it. In case a concrete foundation is installed, the pipe should be full length around each rod.

SETTING COMPRESSOR. After the compressor has been placed in position, block the compressor off the foundation about 4 inch by means of iron wedges, upon which the compressor should set level. Then the cement should be run into the bolt holes and also between the base of the compressor and foundation to insure true bearing all around.

PIPE CONNECTIONS. The steam and exhaust pipes should be as free from L's as possible, and only should be

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used in so far as is demanded by expansion of pipes. All pipes should be thoroughly cleaned before starting the compressor, so that metal chips from cutting pipes may not be carried into the steam chest and score the valves and seats.

Proper allowance should be made for the expansion of the steam pipes in connecting same up.

A drain pipe or bleeder should be provided for live steam, connection being made directly above throttle valve and with the drain, so that the water of condensation may not have to pass through the steam cylinders. If steam connection for compressor is taken from main steam line instead of direct from boilers, the connection should be taken from the top of the steam pipe, thus avoiding the carrying of condensation.

The cocks and drains provided for both steam and air ends should be opened after the pump ceases operation, so that the water may be thoroughly drained, thereby avoiding any possibility of freezing.

In connecting water pipe to jacket around air cylinder care should be exercised to allow for proper drainage of cooling surface and pipes. In cold weather the water should be drained or breakage from freezing might occur in cylinder or jacket.

In piping air discharge pipe use lead in all joints and screw up tight, as air leaks are expensive.

PACKING. After all connections are made and compressor is ready to start, fill the rod and steam valve stem stuffing boxes with a good grade of packing. Cut the packing so that it will fit easily in stuffing boxes. Do not pound it in and be careful that no grit is carried in with it, so as to mar the piston rod. When tightening the gland, remember that a gland should only be tight enough to

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