. American engineer and railroad journal . thiscondition. As previously stated the application of these results is in fixinga constant for the flow of Napiers formula as applied to safetyvalves. The formula is W = AP -4- 70, in which W equals pounds of steam discharged per second, P equals the absolute steampressure behind the orifice or under the valve and A equals theeffective discharge opening in sq. in. This may be stated asE = C X A X P; in which E equals the pounds of steam dis-charged per hour and C equals a constant; the value of E, A andP being given for the tests, C is directly obtai
. American engineer and railroad journal . thiscondition. As previously stated the application of these results is in fixinga constant for the flow of Napiers formula as applied to safetyvalves. The formula is W = AP -4- 70, in which W equals pounds of steam discharged per second, P equals the absolute steampressure behind the orifice or under the valve and A equals theeffective discharge opening in sq. in. This may be stated asE = C X A X P; in which E equals the pounds of steam dis-charged per hour and C equals a constant; the value of E, A andP being given for the tests, C is directly obtainable. Figuring and plotting the values of this constant indicates thefollowing conclusions: l 1 ) Increasing or altering the steam pressure from approxi-mately 50 to 150 lbs. per sq. in. (tests 14 and 10) does not affectthe constant, this merely checking the applicability of Napiersformula in that respect. ( _• > Radically changing the shape of the valve disc outside ofthe seat at the huddling or throttling chamber, so-called, does. FIG. 3.—VALVE FITTED FOR CAPACITY TESTS. not affect the constant or discharge. In test No. 15 the valvehad a downward projecting lip, deflecting the steam flow throughnearly 90 degrees, yet the discharge was practically the same asin tests Nos. 10 and 14, where the lip was cut entirely away, giv-ing a comparatively unobstructed flow to the discharging steam. (3) Moving the valve adjusting ring through much more thanits complete adjustment range does not affect the constant ordischarge (Tests Xos. 16 and 17). (4^ The addition of the muffler to a locomotive valve*doesnot materially alter the constant or discharge. There is but 2per cent, difference between tests Nos. 10 and 13. (5) Disregarding the rather unsatisfactory il/2 in. and 3 valve tests, the different sizes of valves tested showa variation in the constant when plotted to given lifts of about4 per cent. (6) There is a slight uniform decrease of the constant whenincreasin
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