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HOKE R E P O R T S ON FLUID C O N T R O L (1)
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Galling and scoring valve seats plagued valve users and manufac turers for years, until somebody thought of using plastic stem points. This idea worked well at low pressures, but when the pres sure increased — poof! — the valve blew its tip. Up to now, this problem had continued to bother valve makers. Fortunately, a die-hard Hoke engineer insisted he could put a permanent plastic tip on a high pressure valve. We gave him his head and he gave us a plastic-tipped valvestem (using e i t h e r Kel-F or Nylon). His unique design incorpo rates a crimped metal shell t h a t g r a b s t h e plastic tip and really holds! N o t satisfied with this m o n u m e n t a l a c complishment, he pro ceeded to tackle leak problems at the stem p a c k i n g . H e put an O-ring seal on the stem and compressed it with a newly-designed Ny lon collar. The collar serves a dual role, for it also prevents grit and other foreign matter from chewing up the O-ring. Valves of this new design have performed successfully up to 3500 psi. Our die-hard engineer not only ended galling, but also seat leakage, stem leakage and wear problems — all at one swoop.
No. 900-3
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