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Slate & Stone
Consultants: Roofing Slate
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| Home > Penrhyn pumping and power |
| Home | From,
The Penrhyn Quarry 150 years of progress (undated) Printed by North Wales
Chronicle Co Ltd
Caxton House Bangor |
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| Drainage
As may be imagined in the wet weather the Quarry becomes a watershed, pouring water into the lower galleries and, although along the upper self-draining galleries conduits carry away much of the water, yet sufficient escapes to make the drainage question a serious one at the times of heavy rain. |
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| Accompanying is a diagrammatic section through the lower galleries showing the haulage levels, the hoisting shafts and the vertical pumping shafts B1 to C. | |||||||||||||||||||
| The main drainage level is on floor 6. From this level the main drainage adit starts, which is a tunnel 7 feet by 6 feet, mined through solid rock for a distance of 1,837 yards, discharging into the Ogwen River at a lower level. A large volume of the water that enters the Quarry flows to this adit along the built up leets; the remainder, which finds its way to the lower galleries, has to be pumped up to this floor 6. | |||||||||||||||||||
| The de watering system is as follows: | |||||||||||||||||||
| In a mined out chamber at the bottom of Shaft A at point A.1 the following pumps are installed : | |||||||||||||||||||
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| For safeguarding the pumps against the possibility of being "drowned" and placed out of action during heavy floods a dam with a water tight iron door has been constructed at a point A.2, level 9, shown in the diagram. During heavy flows of water the doors are closed, making the remainder of the tunnel and the pump chambers a water tight compartment. | |||||||||||||||||||
| The next pumping units are situated near the bottom of Shaft B at point B.1. They are two hydraulic lift pumps with a capacity of 800 gallons per minute, lifting through two separate shafts from floor 8 sump at C, 130 feet lift delivery to, the adit. | |||||||||||||||||||
| This adit has a very small fall, only 4 feet in 5514 feet, which equals an average fall of 1in 1378. Thus the flow in the adit was found inadequate to cope with the big volume of water pumped and flowing from the Quarry drains. Here a bulkhead has been, constructed in the adit. Two Centrifugal Axial Flow pumps, capacity 10,000 gallons per minute, are installed for lifting the collected water over the bulkhead. | |||||||||||||||||||
| During a heavy fall of rain these
pumps are continually pumping into the adit:
10,000 gallons per minute, or 40 tons. 14,400,000 gallons per day, or 6,400 tons. |
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| To give an idea of the quantity of water handled, 5 days' pumping at the capacity mentioned would be sufficient to provide the City of Bangor, with its population of 11,000 inhabitants, with a year's water supply. | |||||||||||||||||||
| Picture of the de Winton hydraulic lift pump. | |||||||||||||||||||
| POWER
Power used at the Quarry is of four different kinds, namely: electric, hydraulic, steam and oil. |
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| The electric power is supplied by the North Wales Power Company and is received at five sub stations at 20,000 and 10,000 volts. This is transformed to 1,000 and 500 volts, at which voltages it is distributed throughout the Quarry. About two and a half million units are consumed at the Quarry annually. | |||||||||||||||||||
| Electric motors in commission are as follows | |||||||||||||||||||
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| Hydraulic Power. - Use is made of all water available in the vicinity of the Quarry, the main source being the lake called Marchlyn situated about two miles S.W. of the Quarry at an, altitude Of 2,000 feet. | |||||||||||||||||||
| Eight shafts at the Quarry are worked hydraulically, handling 5 ton loads at a time, using an average Of 500,000 gallons daily. | |||||||||||||||||||
| From the same source electric power is generated by means of an impulse turbine wheel and alternator, which has a static head of 366 feet and is supplied by 1,6oo feet of 15 inch pipe, using 4,000 gallons per minute or 8,900 tons in an 8 hour day, generating 250 h.p. | |||||||||||||||||||
| The Workshops and Slab Mills are also driven, by the water from Marchlyn, using another 3,000 gallons per minute, or 6,400 tons a day. | |||||||||||||||||||
| Water from the Ogwen, River is utilised to drive a 300 h.p. Compressor by means of a water turbine working at a head of 47 feet, taking 20,000 gallons per minute or 43,000 tons in an 8hour day. Water from the Ogwen is also conveyed along conduits for working three pumps with a capacity of 1,400 gallons per minute against a head of 180 feet. | |||||||||||||||||||
| A scheme is under consideration for developing the water resources of Ogwen, Idwal and Bochlwvd Lakes, the water rights of which belong to Lord Penrhyn. It is estimated that five million units could be generated annually and thus obviate purchasing current. | |||||||||||||||||||
| Steam Power. - The use of steam is confined chiefly to locomotives, of which there are 29 in number, with a total nominal horse power of 1,500. There are also four steam driven excavators. | |||||||||||||||||||
| Oil Power. Sixteen petrol locomotives with a total of 200 n.h.p. are in use in various parts of the Quarry for short hauls, and prove very efficient. | |||||||||||||||||||
| The horse power used at the Quarry may be summed up as follows: | |||||||||||||||||||
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| Equal to three horse power per man employed. | |||||||||||||||||||
| For maintenance purposes, there is at the Mill a well equipped Quarry Workshop with a small foundry adjoining; and, except for major repairs to the ships, all other repairs are carried out on the premises. |
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