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High Lifter is not a ram pump

And why it is usually better

The High Lifter water pump is not a ram. It uses a completely different principle and exhibits different operating characteristics. These differences are essential when comparing rams with the positive displacement High Lifter.


Hydraulic Rams: How they Work

The hydraulic ram is a device that has been used for over 100 years to pump water uphill. It works on the "water hammer" effect: i.e., it uses the energy of a column of water moving downhill in a pipeline that is suddenly stopped by a valve in the ram. As the water column is stopped, a pressure peak, or "hammer" is created, which can be used to force some of the water uphill higher than the original source. After this sudden short peak of pressure, there is then a depression or "valley" in pressure caused by the shock wave moving from the ram back up the inlet or "drive" pipeline. This slight reduction in pressure permits the valve of the ram to be opened up by means of a spring or weight, thus allowing the process to begin again. Rams usually incorporate an air chamber to assist in capturing the impulse or shock energy.

Although rams are usually mechanically simple, the means by which they transfer energy from the downward moving column of water to the water being pumped uphill is deceptively subtle. Since the shock impulse they use is very short in duration and intense, the energy from it has a tendency to "leak" out. The noise they make is a manifestation of this energy leakage (although not a large one), since it is a shock impulse radiating out into the air. Likewise, the shock of each pulse radiates out anywhere it can: out through the pipeline, through vibrations of the ram, etc. The smaller the ram, the greater the percentage of this energy loss (due to a reduction in volume to surface ratio). Consequently, every means must be employed to reduce this wayward energy radiation if the ram is to operate efficiently at all. This includes using steel pipelines, anchoring the ram to a heavy base, etc.


The efficiency of the energy transfer from drive water to pumped water is dependent on lift height and inlet pressure as well as size of the unit, etc. It tends to be limited in small and medium sized units to no more than 50% and is often much less.

The operation of a ram is essentially a resonance phenomenon and, as such, must be tuned. It uses the shock waves in the inlet pipeline created by the water flow through the opening-and-closing valve and the "elasticity" of the system to create the conditions necessary for its continuing operation. If any of the factors in this balance are changed appreciably, this periodic operation will stop. Thus, changes in water flow or changes in air volume in the air chamber, for instance, can stop operation. The ram must then be restarted manually. Again, smaller units are the most sensitive because they are the least efficient.

In Summary

Rams are a time-honored means of pumping water uphill, and, although they possess some features that may be objectionable, such as noise, tuning problems, installation difficulties, excessive water consumption, etc., they can be very effective if used in the right set of circumstances. Ideal applications are usually those of abundant water supply, low inlet pressure (very little fall), modest lift, and a somewhat patient operator.

High Lifter Pumps

High Lifter pumps, because they use a positive displacement pumping action instead of the resonating water hammer effect, are less troublesome, since they don't require tuning and have a wider range of application than rams. High Lifter pumps are more efficient, quieter, lighter weight, and easier to install. They require less attention and are usually a better choice for most pumping applications.

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