An Inexpensive Flow-Limiting Push-Button Distilled Water Faucet Extending distilled water lines to provide an outlet a t every sink throughout several laboratories in a chemistry huilding can he very costly. Although ordinary pvlyvinyl chloride (PVC) pipe and fittings are not exppnsive, the standard non-contaminatins, spring-loaded > F j @ distilled water faucets commercially availahle are generally extremely ~~. ........ expensive ($30-60): when large numhers of faucets are involved this high cmt precludes placing adistilled water outlet at more than afew strategic locations. The expmaive distilled water faucets availahle from manufacturers of laboratory furnishings are typically nickel-plated, tin-lined hrass. Despite numerous inquiries, we were unable to beate an inexpensive commercial faucet, either metal nr plastic, suitahle or designed for direct use on distilled water lines. At Marietta College we solved this prohlem (and did away with our hernia-pmdueing 5-gal earhays) hy fabricating plastic adapters that allowed us to connect inexpensive, commercially availahle polyethylene push-hutton spigot3 to a PVC distilled water line q u i p p e d with standard p i p e ~ t h r e a d ~fittings. d T h e adapters also serve to restrid water flow, thereby discouraging wasteful use of distilled water. T h e inexpensive spring-loaded push-hutton polyethylene spigot (shown in the figure without its bulkhead fitting) is manufactured hy the New Delphas Manufacturing Co, of Delphos, Ohio and is availahle at $1.25 Rom U.S. Plastics Corp., 1550 Elida Road, Lima, Ohio45805. It. is catalog # 17224-Type " O S p i g o t . Intended primarily for bulkhead use on tanks etc., its shank is molded with ?I4-in.SAE holt threads (straight.-lfi threadslin.) instead of %-in. NI'T standard pipe threads (taoered-14 threadslin.), hence the need for nn adapter to make connection to the standard '&in. N P T fitting nf the water line. T h e adapter, also shown in the figure, is made from relatively inexpensive polyethylene or PVC solid har stock. Ours were made from 1.125-in. polyethylene hexagonal har stock, hut 1.125-in.PVC (round or hexagonal; the hexagonal shape is merely for convenience in assemhling) would he less expensive (less than $2/foot) and easier to machine and thread. One end of a 3-in. length is drilled to a depth of 2 in. and tapped with %in. SAE holt threads. T h e opposite end is turned down to in. diameter fnr314in, " f i b length and threaded outside with standard '&in. N P T pipe threads. Finally, a hole, %sA1a2 in., is drilled as shown, the size depending on the flow rate desired and the water pressure. T h e spigot is screwed into the adapter until i t tightens against the ruhher washer supplied with the spigot, making a leakproof connection. T h e assembly is then screwed into an inside-threaded fitting on the end of the distilled water line using 'l'eflon tape. A 45' threaded elhow on thp water line togethpr with the 4hDoutlet. of the spigot allows vertical positioning of the spout. A short length of 'I4-in. a d . polyethylene tuhing can he fitted snugly into the spout for added convenience. Total cost of the fan& and adapter, excluding shop time, is well under $4. Our system, with ahout 40 such faucets, has already given two years of tmuhle free service. At first, a few of the spigots leaked around the push-hutton when it was depressed, but this was easily corrected hy disasswnbling the spigot (removing the rear washer) and replacing or re-positioning the small ruhher washer that isolates the spring and pushhutton from the chamher through which water flows to the spout. (If the spigot were used only a t low pressures as originally intended by the manufactwer, the integrity of this washer would he unimportant, hut a t the higher pressure of moat distilled water systems it can permit leakage-hut only whcn the hutton is depressed-if it is t o m or improperly positioned.) Judicious placement of hall-type cutoff valves in the distilled water line makes it easy to remove and clean (or replace) faucet assemblies without draining the entire system if a prohlem occurs; e.g., if solid scale, carried over during malfunction of the still, plugs the small bore of the adapter. M a r i e t t a College Marietta. Ohio 45750
658 / Journal of Chemical Education
L a u r a n e e A. K n e e h t
