Kenney me lad, I read you loud and clear here in the frozen South. Al Messer --- kenny <kenny.macdougall@xxxxxxxxxxxxxx> wrote: > Hi just a test can anybody read this > kenny > ----- Original Message ----- > From: "Allen Messer" <al_messer@xxxxxxxxx> > To: "modeleng" <modeleng@xxxxxxxxxxxxx> > Sent: Monday, February 20, 2006 2:08 PM > Subject: [modeleng] Fwd: Re: Re: Lapping, pumps, etc > was > > > > > > > > --- Phill Smith <steam@xxxxxxxxxxxxxx> wrote: > > > >>> Subject: Re: [modeleng] Re: Lapping, pumps, etc > was > > > >> Date: Mon, 20 Feb 2006 13:25:25 +0800 > >> > >> Gents, > >> > >> Modern fluid flow analysis has shown that the > close > >> fitting plunger in a > >> bore causes more problems than it's worth, at > other > >> than low piston speeds. > >> Optimal piston speed is below our "normal running > >> speed" of our models. The > >> greatest efficiency was found to be with a > plunger > >> operating in a free water > >> space of at least twice the displaced volume of > the > >> plunger. The factors > >> against the fitted plunger was due to the > following > >> factors; > >> > >> - Insufficient valve area due to limited space. > To > >> over come this, the > >> valves had to have a high lift. This in turn > >> resulted in water being pumped > >> back down the suction pipe (and/or into cylinder > >> from the discharge valve) > >> for up to 30% of the compression stroke (this was > >> worst on unsprung ball > >> valves). Vapour pressures were entered into in > the > >> worst cases (suction > >> pressures dropped low enough for the water to > >> momentarily turn to steam). > >> > >> - Surge forces, due to rapid water flow in full > >> cylinder, causing high > >> friction losses and extenuating valve opening > time. > >> > >> > >> So, summing it all up......... > >> > >> You'd have a 1/2" plunger operating in a minimum > >> 3/4" bore, with the "O"ring > >> gland mounted as close to the water space as > >> practical within the gland. > >> This can be a screw in (replaceable) > >> gland/guide/support. The guide is made > >> from an extension of the gland which is fed with > >> oil. Two small grooves are > >> placed, longitudinally, on the bearing area of > the > >> plunger carry oil. One > >> top and bottom. The large cylinder will > accommodate > >> larger valves > >> (preferably of the disc type), on the end if > >> possible (with flow axis in > >> line with the plunger) with an area equal to the > >> plunger diameter. > >> > >> This type of pump also allows for 2 different > >> materials to be used for the > >> plunger, and hence compatible bearing materials > may > >> be used for the gland > >> and bearing area of the plunger. Especially since > >> oil can be used as the > >> lubricant. > >> > >> > >> Cheers, > >> > >> Phill. > >> > >> PS Could someone please post this to the > >> "modeleng" discussion group, as > >> I have not yet had time to sort out my "why I > can't > >> post anything (after a > >> certain date) but receive fine" problem. > >> > >> ----- Original Message ----- > >> From: "alan stepney" <alan@xxxxxxxxxxxxxxxx> > >> To: <modeleng@xxxxxxxxxxxxx> > >> Sent: Monday, February 20, 2006 8:07 AM > >> Subject: [modeleng] Re: Lapping, pumps, etc was > >> > >> > >> > I have used stainless, and a reamed bore, and > not > >> had any problems so far. > >> > > >> > I leave a reasonable clearance between the bore > >> and ram so that the > >> packing > >> > is the only thing making contact. > >> > That should (??) prevent galling. > >> > > >> > A reamed bore seems to be sufficiently smooth > to > >> work OK and wear well. > >> > > >> > Alan > >> > > >> > MODEL ENGINEERING DISCUSSION LIST. > >> > > >> > To UNSUBSCRIBE from this list, send a blank > email > >> to, > >> > modeleng-request@xxxxxxxxxxxxx with the word > >> "unsubscribe" in the subject > >> line. > >> > > >> > > >> > >> > > > > > > __________________________________________________ > > Do You Yahoo!? > > Tired of spam? Yahoo! Mail has the best spam > protection around > > http://mail.yahoo.com > > MODEL ENGINEERING DISCUSSION LIST. > > > > To UNSUBSCRIBE from this list, send a blank email > to, > > modeleng-request@xxxxxxxxxxxxx with the word > "unsubscribe" in the subject > > line. > > > MODEL ENGINEERING DISCUSSION LIST. > > To UNSUBSCRIBE from this list, send a blank email > to, > modeleng-request@xxxxxxxxxxxxx with the word > "unsubscribe" in the subject line. > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.