Sometimes it may be necessary to force water through very long lines of hose, or to an unusual height. Steam fire engines are not infrequently called on to give 200 pounds per square inch water pressure. To test short hose lines with anywhere near so high a pump-pressure is dangerous, lest nozzle kick and pull itself away from the man holding it and thrash around; but the ability of the pump may be tested by putting this high pressure-delivery mainly through the safety valve, or in part through the partially closed main outlet gate. _It is not advisable to carry this water pressure above 200 pounds in this test_ at the factory, (although in the shop test the water pressure is carried to 240 pounds) and engine driver should stand with his hand on the throttle. 54. TEST FOR MAXIMUM DELIVERY. _a._ This can best be tried by adding one or, in some cases, two more streams than the pump is rated to deliver by attaching the extra lines of hose to some hydrant near, and then speed up the pump gradually, to see how fast it may be run before violent pounding or slamming of valves begins. Sometimes the increased delivery can be drawn off through an open hydrant-butt meanwhile holding sufficient back pressure to show 100 pounds on the water gauge by partly closing the discharge valve. The engine driver should stand with his hand on or near the throttle when thus speeding the pump. It is all right to run a fire-pump up to the utmost speed possible before water hammer begins, and very often a pump, while new and if favorably set up, can deliver 25 to 50 per cent. more than rated capacity; nevertheless, although expert treatment can force 1,000 gallons from a 16 × 9 × 12 pump we can rate it as only a 750-gallon pump. _There must be some margin to allow for wear and for the possible absence of the expert at time of fire._ THE MAIN POINTS OF DIFFERENCE BETWEEN THE “NATIONAL STANDARD” AND THE “TRADE PUMP” ARE: Brass Plungers instead of cast-iron plungers. Wrought iron side levers instead of cast iron. Bronze piston rods and valve rods instead of iron or steel. Pump has brass-lined stuffing boxes instead of cast iron. Rock shafts are brass bushed. Area of water valves is 25 to 50 per cent. greater. Steam and exhaust passages 20 to 50 per cent. greater. Suction pipe connections two to four inches greater diameter. Cushion valves better arranged. Air chamber is made much larger. Shells and bolting are warranted especially strong. The following necessary fittings are included in the price, and regularly furnished as a part of this pump, viz.: