I. Measurement Of Water

Hard Water is admitted through the inlet pipe to the Lassen-Hjort Patent Measuring Apparatus, flowing into one of the compartments of the double - chambered receiver (AA), Fig. 218. When the compartment is filled, the locking gear (B) is automatically released, and the receiver falls, discharging an exactly measured quantity of water. Simultaneously the other compartment is brought under the inlet, filled, and discharged in turn.

The incoming water thus operates the measuring and proportioning apparatus in a simple yet absolutely positive manner, measuring off at each discharge a definitely determined quantity of hard water for treatment. Each measured quantity of hard water is delivered through the chute (C) into the intake tank (D), where it has added to it the exact quantity of reagent solution required to soften it to the degree of hardness guaranteed.

H. Measurement of Reagents.- The reagents are added to the measured quantity of water by the positive measuring valve (E fitted in the chemical container (f), this measuring valve being directly actuated by each discharge of the water. The chemical measurer is capable of closely accurate adjustment, so as to discharge the exact specified quantity of reagents required to soften each separately measured volume of hard water. The amount delivered can be regulated as required over a wide range to correspond with any variation in the hardness of the crude water. The agitators in the chemical container, which are actuated by every movement of the water measurer, keep the chemical reagents constantly in a state of perfect homogeneous mixture.

Fig. 218.

Alter being thoroughly mixed with the chemicals by its turbulent motion in the intake tank, the water passes through the downtake (G) into the main settling tank (II) in which the reaction is fully completed and the precipitated im purities arc deposited. The heavier portion of the sludge so formed sinks at once to the bottom of the plant and is removed by the periodical use of the sludge cock (I), while the lighter precipitate rises slowly with the water and is retained by the wood fibre (J), so that the water, which is evenly collected by the weir (K), leaves the plant perfectly suit and crystal clear.

The reagents are conveniently prepared at ground level in the mixing tank (L) and pumped by the pump (M), operated by hand or power, to the chemical container (F), thereby avoiding all labour in taking the raw materials to the top of the plant and preparing them there.

Every l.assen-lljort plant is installed under a stringent guarantee that it will reduce the hardness of the water to a definitely stated figure (often as low as 2 degrees Clark).

Working Instructions

Chemical

Re Agents

To soften 10,000 gallons of water of the same quality as the sample analysed, the following chemicals are required.

Burnt Lime, Carbonate of Soda, and Water, in the proportion determined by the sample analysed.

The solution should be made up in any small tank or barrel. The Lime should be slaked by sprinkling it with water before being placed in the tank, the requisite water being then added gradually, keeping the Lime solution stirred all the time. When the Lime-Milk has been prepared the Soda should be added, and the whole stirred up well before it is poured into the chemical container of the Measuring Apparatus. The solution should be passed through the strainer, placed on the top of the chemical container, attached to the water measurer, in order to remove any foreign substances.

Lime

It is essential to the successful working of the Softener that the lime used should be of the best quality, and be as fresh burnt as possible ; it must not contain any hard lumps which will not dissolve. Buxton Lime is recommended, but if this is unobtainable, any good local chalk lime will serve the purpose.

Soda Ash

The trade term for the Soda Ash recommended is Carbonate of Soda (58 per cent, pure alkali).

Cleaning The Softener

The drain cocks should be opened for a few minutes every day ; the filters should be cleaned out when the water from the last filter begins to show white. The tanks should be emptied and filters washed through from top by means of a hose once a month, or as often as may be required to keep them in an efficient condition. After the filtering material has been rinsed it can be used over again.

All working parts should be well lubricated, and it is advisable to clean out the chemical container once a month.