Document ypJJXykDrEmEVK0yjn0kmoR36

CYPSUIi rT.CDUCTS :i-:UAL Chapter IV Factors Affect inn Hose Pressure "sing a plaster especially formulated for machine application mu maintaining proper r.ortcr consistency are necessary to keep hose presauri at a minimum, but thor.. arc also several other important factors. 1. Hose length - Pressure varies nearly directly "ith length of hose used, A pump (cylinder or -Toyno) will develop approximately twice as much pressure with a 60* hose as it will with 31' oi the same hose, 2. Hose sice - Diameter of hose is definitely a factor. If pressure for 60* cf 2" hose is 90 psi, pressure required for 6C' of l'!" hose would be about , 165 psi, 3. effect of height - In addition to pressure developed with an length of hose, about one-half pound, per sq. inch must be added for every foot the plaster is elevate^. For examnle, if the machine is on th^ ground and the hose is run up to second floor, which is 301 above ground, there will be an extra 15 psi hose pressure.. 1. Proportion of i-g are gate - A rich mix (2 to 1) will, 'usually result in more pressure than a leaner mix (3 to 1). The richer nix will usually have to be slightly thinner than the lean one in order to get same capacity from the machine. 5. dorters containing vemiculite aggregate normally pump with considerably less pressure than those containing either perlite or sand. ..er.ember, high hose pressure results in lower capacity and more machine vicar. Bestwal] gun plasters are formulated to pump with as low pressure as possible and at the same time worl: good under the tools after being sprayed on the wall or ceiling. Spraying Acoustical Plaster Eestwall Light Acoustical plaster was formulated especially for machine application. It works well in -all type machines. Hose pressure is not normally a problem with this type plaster as it pumps easily with a low pressure. The Nozzle The nozzle of all plaster machines are basically the sur.c.. The mortar goes through an orifice, most have several interchangeable orifices varying ir. diameter frem 1/L" to 5/8". Compressed air is fed to the nozzle. The mount of air, consistency and type of mix, volume of mix and size of orifice - etcrmir.e the spray pattern. The nozzle operates tr' emitting a globule of mortar, then air, then mortar. Lot: frequency cf thi: cycle results in large globules of mortar while high frequency results in very small globules. To lower frequency: (1) Use lower air pressure (2; Use larger orifice (3) IT air stem is adjustable, use greater distance from air stem to orifice. To increase frequency, resulting in finer spray pattern, reverse above prcceaurc. L. 0133 Toverb-;.' 1, 1958 SGP 0018930 PLASTERING .UiCHIi'LS QTc'y.i F?:" DUCTS riAUUAi Chapter IV yhat To Do '..rhen Tbcublc Occurs 'Pith hachire Amalicu.tior. Trouble Plaster volume is too low Nozzle clogged with lumps Plaster rebounds from wall in operator's face Hose pressure too high Fluster comes out in stream when breaming Nozzle spray too narrow Aggregate tends to separate out Plaster slumps on wall Cause or Pur.edy Too much hose being used cr pump worn Euildup of fibers, set plaster or foreign matters. Lever air pressure, If spray pattern is lo-t use larger orfice. . ix too stiff, hose too long or small diameter, fittings clogged or aggregate being used requires too high pressure to pump. Increase air pressure. If this does not remedy trouble, use smaller orifice, or use thinner consistency mortar. The pressure is too low or orifice- too large for plaster volume. Using too much aggregate. Happens more frequently when using sand aggregate. Usually due either to too thin a mix or too much aggregate. L.C13L November 1, 1558 SGP 0018931