To do this, it is best to select packing which will permit a number of narrow rings to be used instead of a few wide rings. The rings next to the bottom will become dry and hard before those next to the glands of the box are half worn out. If a number of narrow rings are used, the dry ones may be removed and duplicated by new ones and replacing the rest of the packing in the stuffing-box. This method economizes packing and secures a tight yet freely working rod.
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When patent square packings are used, it makes less difference whether the rings are narrow or wide, because the surface in contact with the rod will be nearly continuous in either case.
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When cutting packing rings, the length should be such that the ends do not come together within 1⁄8 inch when put into the stuffing-box, and the rings are put in to break joints, which prevents leakage through them.
When inserting this packing, the rings are put in one at a time, using a piece of hard wood to push them to the bottom of the stuffing-box and firmly against one another. The stuffing-box should be filled as full as it can be, and start the nuts on the studs by hand. Screw up the nuts with the hand and then start the pump slowly. If leakage occurs do not attempt to tighten the nut while the rod is in motion, and in all cases tighten it only enough to stop the leakage. A slight leakage at the water end is not harmful. A little cylinder oil and graphite occasionally applied to the rod will tend to keep it smooth and bright, which condition is favorable to the durability of the rod and of the packing.
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When cutting rings of packing for the water piston or plunger, the rings should be 1⁄8 inch short, as previously described, page 372.
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Packing should fit the grooves in solid pistons moderately tight, so that the packing can be pushed into the grooves with the fingers. The depth of the packing should be such that the piston will fit the bore of the water cylinder snugly when first put in. If packing of the proper depth cannot be obtained, it is better to have the grooves turned to receive standard sizes of packing and not require special sizes. Cutting hydraulic packing is a tedious job, consuming a great deal of unnecessary time.