"ملف ١٨/ ١١ إصلاحات المباني - مباني الوكالة - مراسلات بخصوصها - مضخات المياه لوكالة البحرين." [ظ‎‎٩] (١٥٠/١٨)

after they have been working many years, and with waters which
are not corrosive to gun-metal (and very few waters are), these
Hydrams will be found nearly as good in 50 years as they are when
first fixed. Even for the larger Hydrams and “ B ” Hydrams, the
annual cost of repairs and renewals seldom averages more than
20/- to 30/- after they have been in use 15 to 20 years.
Hydrams of Hydrams are divided into two classes : “ A ” type and “ B ”
Two Kinds.
type.
“A” Type Hydrams
Raise Part of
Driving Water.
Driving Water
Required.
These raise a part of the same water that works them. The
exact amount of water raised depends upon the working fall and
the vertical height to which the water has to be raised above the
Hydram. The smallest sizes can be driven by small springs or streams
delivering as little as half a gallon of water per minute, whilst the
larger sizes can utilise streams of 2,000 to 3,000 gallons per minute.
Adjustable to
Work with
Varying
Quantities.
They can be adjusted to work with any quantity of driving
water from their maximum capacity to less than one-half thereof,
so that, in cases where a stream or spring driving a Hydram is
subject to diminution in a dry season, the Hydram can be adjusted
accordingly.
Working fall
Required.
The “A” type will work with any fall down to 15-in. (if the
height to force the water be not very great in proportion), but
the greater the working fall the less the cost of the Hydram to raise
a given quantity of water, and the less water is required to drive it.
Sizes made.
They are made in sizes to raise any quantity of water from
150 gallons per day up to 500,000 gallons per day.
■i;
v