Manual of experiences ans tolerances in rope pump production
A.d. THE PIPES.
The pipe is a conduct in which the column of water to be extracted is formed, and has
the following characteristics:
- Made of PVC.
- Designed for pressure.
- Meets ASTM D2241 standards.
CHART OF NOMINAL AND REAL DIAMETERS OF THE PIPE.
| PVC pipeOutside diameter |
|---|
| Nominal | Real |
| 1/2" | 21.34 mm |
| 3/4" | 26.67 mm |
| 1" | 33.40 mm |
| 1 ¼" | 42.16 mm |
| 1 ½" | 48.26 mm |
| 2" | 60.33 mm |
| 3" | 88.90 mm |
| 4" | 144.30 mm |
The recommended pipe should meet ASTM D-2241 standards. All piping is the pressure type
used for potable water.
In Nicaragua, measurements are in inches, whereas other countries use millimeter
measurements, requiring adaptation.
In the technical drawing manual, there is a table entitled "Variation of Measurements for
Pistons and Rope" in chapter 4 and in chapter D is "The Installation Accessories" chart.
Pumping pipes vary according to the depth of the well. The deeper the well, the smaller
the diameter of the pipe. The combinations of types of pipes according to depth are based
on experience. Going beyond these limits can cause the rope to slide on the wheel over time.
The rope with pistons can support the weight of the water column in the pumping pipe. The
maximum weight of the water in the pipes is 10 kilograms and should not be exceeded.
Therefore, if pipes with different measurements are used, the maximum depth should be
adapted to the maximum weight of 10 kilograms.
Deficiencies have been encountered in the pipes depending on their origin of production.
Examples of these, which can affect the pumping pipes, are:
- The inside diameter does not meet standards. This causes a problem when the diameter
is smaller than what has been established because the piston will not fit or will fit
but cause friction.
- The inside walls of the pipes are rippled, which can cause unforeseen friction.
- The jacket is not made correctly. Some jackets are found to have a narrowing, right
before the widening, where the pistons stick.
These problems are more sensitive in the case of ½" and ¾" pipes.
Care must be taken in the handling of ½" pipe. Heat from the sun can cause contraction
and deformations in the pipes causing the pump to malfunction or function with friction.
Handling and tying up during transportation, together with the heat from the sun can ruin
the pipes.
Dust and dirt in the pipes are always obstacles when installing. Storing of the pipes,
therefore, requires some care.
The type of pipes used for irrigation or drainage is less expensive but with a smaller
wall thickness and is not used for rope pumps.
Metal or flexible pipes are never used in rope pumps, as they are not appropriate for
this type of equipment.
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