Question

Q1. The following data is given for a lever-loaded safety valve mounted on the boiler: Valve diameter 75 mm Blow-off pressure 1.25 MPa Yield strength of material at tensile 250 N/mm2 Factor of safety 5 Allowable bearing pressure 20 N/mm2 Length to diameter ratio for pins 125 1 Width to thickness ratio for lever 3 1 The distance between the fulcrum and the pin connecting the spindle of the valve to the lever is 75 mm. The distance between the fulcrum and the dead weights on the lever is 750 mm. The lever has a rectangular cross section. Determine (a) the diameter and the length of the pin connecting the valve spindle to the lever, (b) the shear stress in the pin, and (c) the dimensions of the cross section of the lever. [20 marks]

Answer 1

Solulien- 1. 2. Fulenum ←-value (Sbam ru Ch en 2. mn

uduad. a uo ,that. blouss out until the pr falls to the uquirud Jimiting valu and tun unlor audewmai callg clenud Se u → The maximum A team lead F, at ushich tu, valve bl ead F, at ushich tu value bleuss last (75) (1.25) = SS 22.33 N -0 4 ful crum ed

e- Fen agyam 7S Banding Mem nf gia gram 3727 SS. 2S N-mm 5S 22 33 SS2 23 he peint ora F subpichid lo marimum fore and at such d, and t diamatun and th of te P at F anagin that 5522.33 2o (dix 1-2sd)

e- Fen agyam 7S Banding Mem nf gia gram 3727 SS. 2S N-mm 5S 22 33 SS2 23 he peint ora F subpichid lo marimum fore and at such d, and t diamatun and th of te P at F anagin that 5522.33 2o (dix 1-2sd)

d21 0 83m dl= 14.86 mm tun ca = 18.75 mm and bin a 牝 -2s。 て O-SX250 = 2S Facten of Saf t in ububuct in

Jun than fera adingen tbindlu pin (F). C ahng en u dimu iom aenam paau Mb (750-75) Nb 31 27 55, 2S N-mm tun G x b (3b) ' (b 17.66 mm