Document YDLv06LbG7QNdyX6GEd160EpV

ARGUMENTS Here*i the place to unload your gripes to editors, and fellow engineers . ______ How SO Armstrong traps 14 tons of coall per month.. . Follow the Arrow Valve Won't Work If Stem Breaks Off Modern STRAIGHT-THROUGH valves are specifically designed gtS is no need for pressure on topTjfl; disk. Installation with prestan^S the disk is correct, as shown &% drawing (ian. "Argument CctpOT This way disk protects ptckiajff valve is opened- Many valves have a direcMousl/gft embossed on tba body to insure.pn?5 installation in the blowofl line. J F Curtis Detroit, niu Referring to "Valve Flow Reversed?" (p 136, Jan Power) I think the better installation is one where pressure enters under the seal. The Illustration is cor* rect as you showed il. It Assume that pressure is* above the 'seel and stem breaks in the bonnet thread, or between bonnet and wheel. If valve were closed it could not be opened (to lower water level in on em ergency). On the other hand, if It were open it could not be closed, so boiler would have to operate temporarily with only one blowdown valve. It would be better to have the valve open rather than closed, because one valve would be usable and the boiler could run until repairs were made. In addition, this valve is normally Consider the Sediment 1 acme with the editors. Flow through valve (p 136, Jen Power) is right. While there is no code requirement that pressure must be under the sesi, avoiding a sediment trap is n good reason for preferring this arrangement. Ha sard of accidental blowdown through on open valve, cited by Ryan as an argument for preasuro on (op of the disk, is very real. I know of at leost one boiler completely blown down be cause of a loose disk. Rut his proposal for eliminating that haxard only intro duces a new one*--possibility of a sedi ment trap. ASMS Boiler Code indicates correct solution. It says nil stationary boilers carrying over 100 psi must have two blowofl valves. Possibility of .both valves failing at once is negligiblo. [ think any good engineer will see that his boiler has two blowof! valves regardless of pressure. E F Fernm Maryland Casually Co Baltimore, Md. closed, and with pressure the seat pack ing it not required to do any sealing. To the best ol my knowledge, there is no code requirement that pressure enter over or under the seat of a blow down valve. For pressures above 100 psi, code requirement Is two valves on each blowdown line. Best operating practice it to open wheel on outer valve first, then blow down by opening the inner one. In clos ing, inner valve should be closed first, nest the outer one. This puts most of the wear on inner valve, lets outer one do good job of sealing. If either stem breaks, boiler can still operate using the other blowdown valve. F Ptackk Yornall-IParing Co Philadelphia, Pa. Watch That Shock! W Utah's advice about reversing valve flow so pressure is against the' bonnet (Jan`Power) could be extremely dan gerous. He reasons valve would close If stem broke. Bui sudden closing of valve during passage ol high-velocity blow down water would cause severe shock pressure. Shock pressure is proportional to volume or weight plus pressure or velocity. Manufacturers' shock tesla show that sudden stoppage of flow re sults in 10 to 100 times the initial pres sure. Assuming the boiler preuure at 1500 psi, sudden valve closing would room preuure to somewhere between 15,000 and 150,000 psi. Rupture or failure of valve, piping or joints would follow. An operator (if be lived) wouldn't be able to close valve next to boiler even [f valve and piping between it tod blowdown noxxle were still undamaged. Art Belton Montreal, P. Q. Why Is 3226 Psi Critical Preuure? .r,sThe board or examiners of boilkiS spectors asked me to give four .3$ why stesm can't form above 3226(5 I gave them these two rusooi;t(fi] No latent heal. (2) At that preirajj steam and water have same densltyfir you can't tell where the wafer linriij the gage glass. Docs some reader have a full tarn to satisfy the inspectors' question?j A J Kuchinsky Arlington, Matf^ Diesel Cylinder Wear I've just read If P Yount's title] "The Life of a Diesel Liner" (pillfl Aug Power), and I would like to`i<Ul a few comments. Several years ago I surveyed 100 tjj cycle diesel engines of 14- and -l$jgjj sixes. Although 1 have always feUitk* woar should be less on a 4-cycle tnS on a 2-cycle engine, my results,tag firmed very well the wear of -001* per 1000 hr operation, diiregsrdini[i0 first few hundred hours. Also, I footdl that a wear of .005 in. per in. diimttSM before replacing or reboring wsjw pretty good rule to follow. Wear on direct reversible mariaa-t^ gines was oboul twice that on slatifS ary engines. I attributed this to'vffi number of starts and stops, and t?;l3 foot that salt-laden vapor could^ drawn into the cylinders. Best records were made by *nd?S in ice-plant service, operating ously for months at a time, Here averaged around .0005 per 1000 ht-H* I believe that wear is affected bf'|a temperature and quantity of. water. An outlet temperature of l&a 140 F is about idoal, with o elieol**j!8ffl of % gpm per hp. E C Cole Caracas, PLANT OPERATION AND MAINTENANCE SECTION in tr|H or* **llohl in iM* mm;k*fl* iftitt-wp nwiti fcorfy ptpins r*eir*m*nt*. rS EjWlI 1933 AN BXAMPLE of(he benefit to begained from Armstrong Unit Truppingisfound in installation at M. Wile A Company, Buffalo, N.Y., clothing manufacturers. A single aream trap was being used to drain each group of 4 to 6 pressing machines. After changing over to the use of an individual Armstrong trap on each of the fifty presses in tne plant, the-company reports that, because of the resulting more efficient use ofsteam, Con| consumption dropped by 14 tons * n'on,h- There was no reduction in work load. This fuel saving when held up against sn investment of about $500 in steam (raps was rightly considered a goot/ trade. There tre other advamtgei to Arm strong Unit Trapping. Almost invari ably machine temperatures are higher, heat-up is faster and output is increased. The traps themselves are thoroughly reliable, seldom need attention. The design, materials and workmanship in the trap mechanism* for low and medium pressures are identical to those used in Armstrong traps for power fdant service at 900 degrees F and 950 bs. pressure, so they last for a long, long time. Your local Armstrong Representative will be glad ro discuss the savings pos sible in your plant through Armstrong Unit Trapping. Call him, or write: ARMSTRONG MACHINE WORKS III Mae!# Itraet Thraa ftlvarv, Michigan You Alwg ftLQfMtv EffWifflf. yft-n Yftii U. AirntWann Unit TwwIm JU1T CUP TO TOUR COMPANf ilTTIRHfAD AMO MAIL AttMSTBONO MACHINE WORK* 12 j*epl* street. Three River*. MIWs* Pt*o* i**4 me *Nem Trap *k, | 0>v* Ccophlt Octette Till*.............................