The chief difficulty with acids is their corrosive action on the materials employed in pump construction, necessitating the replacement of the ordinary materials by others less liable to destruction.

A common leaden lift-pump adapted for use with acid which is neither strong nor hot is shown in Fig. 59: a, wooden plank, 5 ft. X 11 in. x 2 in.; 6, iron handle and support; c, iron rod; dt iron stay; e, copper plunger-rod; f, leaden box with spout 1 1/2 in. bore; g, leaden barrel 2 1/2 in. bore; h, iron plate; i, iron bands; k, leaden ball valve; l, leaden supply-pipe 3/4 in. bore; m, rubber packing ring; n, leaden ball valve.

Doulton's stoneware force-pumps for acids, bleach liquor, alkalies, vinegar, etc, are shown in Fig. 60. They can be used in connection with stoneware socket piping if required, and the various parts can be had separately in case of breakage. They range from 1 1/2 in. bore, 6 in. stroke, raising 44 gal. per hour, and costing 70s., to 6 in. bore, 15 in. stroke, raising 1800 gal. per hour, and costing 175s, These pumps are arranged to work by steam power. The plunger is of stoneware, Accurately ground to fit the stuffing-gland, this also being ground on the working surfaces. Asbestos is used for packing.

Pumps For Acids 40069

The valves, which are of the form usually known as "butterfly valves," are ground accurately into their sittings, the rise being adjusted by the stoneware crossbat, made In the ware above. The jointing of the parts is made by means of a circular groove and fillet fitting into each other, packed with rubber or asbestos, the flange being clipped by two sets of iron semicircles crossing each other, thus forming a continuous ring, through which the bolts and nuts pass as shown in drawing. Stoneware barrels arc also carefully made for lift-pumps with rubber buckets. The difficulty of grinding the interior surface of the slider being considerable, this arrangemcnt is not in practical use. The ram is hollow, hiring an iron rod for attachment passing through the centre, the end being stopped with some acid-proof material, such us sulphur. The iron parts are coated with rubber or varnish, as may be necessary for the purpose to which the pump is to be applied.

Fig. 60

Pumps For Acids 40070

The application of compressed air to the surface of acid contained in a close vessel with an outlet is much adopted in large works. The vessel containing the acid is usually of cast iron lined with stout lead, and the air pumps are driven by steam. Such apparatus is best obtained from well-known makers, such as R. Daglish & Co., St. Helens, and E. R. & F. Turner, Ipswich. Also W. H. Bailey & Co., Salford, make a special pump for hydrochloric acid.

A very handy contrivance for drawing small quantities of acid from carboys, etc., is known as Nichols' acid pump. This apparatus is securely fixed by a thumb-screw on a pedestal, to be readily adjustable for height. The pedestal is supported on a miniature platform (easily extemporized from an old box), which again is placed on the rubber bulb b. The glasses are very carefully ground together and secured At the joints by screw couplings, making them perfectly nil-tight. The 2 valves c are fitted to their places and carefully ground by machinery, which drives the air into the chamber between the glass cups. In use, the rubber bulb is compressed by the hand. The lower valve remains tight, and the air escapes through the upper valve. The hand, now removed from the bulb, allows it to expand, and as a vacuum is created in the chamber, the upper valve closes, and the acid rises through the section tube into the chamber to fill the vacuum. Another compression of the bulb drives the acid up through the upper valve, and the chamber is again tilled with acid; as this operation in repeated, the liquid flows from the nozzle d of the pump.

The relative capacity of the chamber and bulb is so nicely adjusted that the acid never rises high enough n this chamber to enter the hull.. It will be noticed that an air-chamber is formed at every joint by a downward projection of the top piece; this prevents the acid from ever reaching any.

Pumps For Acids 40071

Fig. 61.

Pumps For Acids 40072

A discharge-tube attached to the nozzle of the pump extends to a point just below the bottom of the carboy, so that continuous pumping for a short time will give a siphonic action which can be instantly arrested at any time by the removal of the bulb from its nipple. A metallic bulb may be substituted for the rubber one, giving greater power. By means of a metallic bulb, a large tube may be used on the siphon, which will be capable of emptying a carboy of sulphuric acid in less than 3 minutes. The pump consists of a pump and siphon, which becomes self-acting after a few strokes of the bulb. Once set in motion, the acid flows until stopped. Its action is rapid and perfect. The glasses are entirely enveloped in a tight cast-iron covering, and the apparatus is light, durable, and perfect in its action. Any quantity of acid can be drawn without the least danger to clothing, person, or floors, and the person using the pump may be entirely inexperienced.