Tuesday, June 15, 2021

Why we half turn the hydraulic jack,while we loosing hydraulic nut?

  • When hydraulic jack is pressurised, the bolt is elongated and the load is taken by the jack to loosen the nut, and the nut is turned back up. 
  • On releasing the pressure, the bolt will go back to its original size, thereby causing the loosened nut to get jammed with the moving piston of the jack.


Wednesday, June 9, 2021

Pneumatic coupling

  •  Pneumatic quick couplers (also referred to as air couplers, or pneumatic quick disconnects),  are primarily used for pneumatic applications, connecting air tools, hoses, or other implements to compressed air supplies. 
  • The coupler half contains a shut-off valve that is automatically opened when a mating nipple is  inserted and automatically closes when the nipple is removed.  
  • Parker pneumatic couplings come in three basic designs: general purpose/manual connect,  general purpose/push-to-connect, and special purpose.  
  • The standard seal material for shut-off couplers is Nitrile.


Tuesday, June 8, 2021

Self healing property of stainless steel

  • The alloy nature of Stainless Steel and its thin, transparent layer on the surface provides a self  
    healing feature. When activated by oxygen within the air or water then it is this layer which  
    repairs lightly scratched or any damage to the surface. 
  • Stainless steels contain a significant amount of chromium, which forms Chromium Oxide  
    when it oxidizes (rusts). 
  • In contrast to a simple carbon steel, which forms iron oxide when it  
    rusts, (the flaky reddish brown oxide we typically associate with rust). 
  • Iron oxide is brittle and  permeable, doing little to prevent further oxidation of the steel surface. In contrast, chromium  oxide does not have an objectionable appearance, being the same effective color as the base  metal, just a bit duller, and is hard and resilient. 
  • When you scratch or mar stainless, the  
    exposed chromium just forms a new oxide layer, protecting the underlying metal.

Engine cylinder pressure is 120 bar why you are tightening cylinder head at 1200 bar

  • Pressure = Force / Area 
  • So Force = Pressure x Area 
  • We know that Pressure = 120 bar, Lets take cylinder bore = 60 cm 
  • So area of head = ㄫ r x r = 3.14 x 30 x 30 = 2826 cm2  
  • There for Force acting on cylinder head = 120 x 2826 = 339120 Ncm  
  • In order to keep cylinder head in place we need to apply a force that is greater than 330120  
  • Now cylinder head is tighten with 8 hydraulic nuts and assume area of one nuts as 100 cm2  
  • For safety we take the force needed to keep head in place as 800000 Ncm 
  • Now There are 8 nuts so total area = 8 x 100 = 800 cm2  
  • Pressure = 800000 / 800 = 1000 bar  
    So we need to tight nuts around 1200 bar


Thursday, June 3, 2021

Boiler water level controller : Components and Working