RAM PUMPS
How does one get water to a higher elevation without
carrying it or using a hand pump? If there is a running stream or spring that
flows briskly, it is possible. The answer is found in a Hydro Ram pump.
A ram pump requires hydraulic pressure to operate the pump
(Not electricity!), so a drop or "head" is mandatory to make the pump work.
The ram pump then uses the energy generated by the weight of the water to
continuously pump a fraction of it uphill – up to 10 times the "head" or fall
feeding the pump. When the ram pump's poppet valve (the only moving part) is
open, water flows downhill through the supply pipe to the pump and escapes out
the open valve. That is waste water, and is utilized to generate the kinetic
energy required to pump some of the water up the delivery pipe. As the water
gains velocity in the supply, or drive pipe, it causes the poppet to snap
shut, which causes hydraulic pressure to peak immediately (a "water hammer"
effect), which forces some water through a check valve, and into the delivery
pipe. This cycle repeats itself about once a second.
For those who have a mountain stream which could provide
water to a cabin at a higher elevation, it is possible to add a reverse
osmosis water purifier to the ram pump, so creek water can be delivered to a
holding tank in pure condition.
The ideal situation is to use a ram pump in combination
with a large storage tank situated at least 30 feet higher than the home. As
the ram pump operates continuously, a smaller ram pump can fill a storage tank
that can be drawn down during the day, for example. And assuming a pressure
factor of 0.54 per foot of drop, or more realistically 0.50 with line loss
(friction), an elevation of 30 feet would deliver water to the ground at 15
PSI. That is certainly good enough to deliver water in quantity for most uses.
Ram pumps have been around for a least a century. The
older, bell shaped ram pumps manufactured by Skookum were made of cast steel,
and lasted forever. They also cost a small fortune. Now there is an
alternative, made from PVC, which will handle falls of 15 feet and lifts to
150 feet reliably. And, they are relatively inexpensive. If the fall is over
15 feet and the lift required is over 150 feet, then a more expensive steel
ram pump is indicated.
The installation of a ram pump is not overly complicated,
but it does require some study. You have to know how far downhill you will
have to "pipe" the water before you get a sufficient "drop" or "fall" to
operate the pump, how high and how far the water needs to be pumped, and how
much water will be needed per 24 hour period. Once those basic factors are
determined, you will then need to study the catalogue from Fleming Hydro-Ram
Pumps very carefully to choose exactly which size pump will work for your
individual situation.
For more information on ram pumps, contact
Fleming Hydro Ram Pumps
PO Box 698
Amherst, VA 24521
phone: 804-277-8511
OPERATION OF A HYDRO-RAM
Things to consider:
1. How far downhill you have to "pipe" the water before you get a sufficient
"drop" or "fall" of water to the pump;
2. How high you need to pump the water uphill;
3. How far you need to pump the water;
4. How much water you will need pumped uphill over a 24 hour period. How ram
pumps work:
When the pump's poppet valve is open, water flows downhill through the supply
pipe to the pump and escapes out the open valve. This is the waste water that
is used to bring the water in the pipe into motion where it's kinetic energy
can be utilized.
The water flowing in the pipe is quite heavy (water weighs about 8 pounds per
gallon). As the water gains velocity in the supply pipe ("drive pipe"), it
causes the poppet to snap shut. This sudden closure of the poppet causes the
hydraulic pressure in the pipe to peak instantly (producing a "water hammer"
effect) which forces the water though the pump's in-line check valve. Here the
high pressure flow runs head-on into the back- pressure in the output line
(the "delivery pipe"). Part of the water flow is forced up the air chamber,
compressing the captive air and causing the water flow to lose most of its
energy. As the peak water pressure subsides, the compressed air in the air
chamber acts as a piston, pushing downward on the column of water. This causes
the check valve to close and forces the water to seek the path of least
resistance... up the delivery pipe.
When the check valve closes it causes a momentary pressure drop and a slight
suction to occur on the supply side of the pump. This causes the poppet to
reopen and the process continues repeating itself at a rate of about one cycle
per second.
This cycling of the pump also produces a significant shock-induced pressure
wave that rapidly travels back up the supply pipe. For optimum operation of
the system (Le., the most water being pumped uphill), it is necessary to
"tune" the supply pipe so the shock wave works for you rather than against
you. The proper placement of a "stand pipe" is the primary method of tuning
the pump's frequency.
The Fleming Hydro-Ram can lift water approximately 10 feet for each 1 foot of
fall of the water from the water level at the drive pipe's intake point to the
pump. For example, if you need to pump water 30 feet uphill, then you will
require a minimum fall of 3 feet (a 10 to 1 ratio). However, in order to
achieve a greater output of water at this lift, it is better to keep the
fall-lift ratio as small as practicable. We can achieve a 5 to 1 ratio by
increasing the fall of the water to 6 feet (6 x 5 = 30).
Where practicable, go for a greater fall of water to the pump in order to
increase the output of the water pumped uphill.
If you require lifts of greater than 150 feet, we (Fleming) recommend using
the steel 3" Fleming Hydro-Ram.
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