The installation procedure is straightforward and can be done largely by unskilled labourers with the help and guidance of someone having a basic knowledge of construction and mechanics. Several hundred Floppy Sprinkler Overhead Systems have been installed around the world and these guidelines have been compiled with the knowledge gained from the advice and impute from many different people. Floppy Sprinkler (Pty) Ltd. will welcome and appreciate any suggestions you might have to improve and simplify installations. 

STEP 1

Measure and mark out the boundaries of the field/s and clear the surface of all unwanted vegetation, large rocks and other obstacles such as old fences or structures. Do not plough or rip the land at this stage, as it will only make it more difficult to work on. If the field/s have already been ploughed and/or ripped, the surface should preferably be prepared in such a manner that a vehicle can move easily across the surface. 

STEP 2

Measure out the positions of the poles and anchors, making sure that they line up in all directions and then mark them with a large lime cross with a peg in the center. (The lime crosses make it easy to accurately position a pole once the hole has been dug). 

Ensure that the positions of the anchors are accurately aligned with those of the anchor poles.


STEP 3, 4 AND 5 - SQUARING METHOD

STEP 3

While the setting out is being done, drill a 8mm hole 70mm deep, 100mm from the top of all the poles. Screw in M12 x 90mm couch-screws into the holes in the anchor poles and do the same with the support poles but include a penny-washer. (Fig. ?).  

When installing poles it is most important that these couch-screws face in the correct direction. In the case of the anchor poles the screws face inward towards the field away from their respective anchors and those in the support poles face across the field at 90°, all in one direction.

STEP 4

Dig or drill the holes for the anchor and support poles, do this in rows so that the installation of poles can be initiated while the balance of the holes is being dug. Ensure that the holes are not too big, but are the correct depth. Too large a hole does not make for a solid immovable installation, as too much soil must be back-filled around the pole.  (See also poles)

Nuwe CAD skets met veranderinge.

STEP 5

If concrete anchors are being used, make sure that the holes are dug in the correct position. The distance of the front edge of the hole from the anchor should be; the height of the pole above ground level plus 1 meter. This is to ensure that the anchor cable will be at an angle of 45° to the ground. If the hole is positioned any closer to the anchor pole the angle will be greater and the effectiveness of the anchor’s holding capacity will be reduced. The holes should be about 500 x 500 x 500mm and 1m deep. 

Concrete cast in-situ should be at least 18Mpa and 300-400mm thick. It should be allowed to set for at least 7 days before any strain is placed on it.

A 12mm rod, with a small eye bent and welded closed on one end and some short rods welded on the other end, to give it some purpose, must be cast into the concrete. 

This rod should lie in a groove cut into the front edge of the hole, angled up at 45° and aligned with the anchor pole. It is important that the groove is cut deep enough so that when strain is placed on the rod, it does not in time cut further into the soil and cause the anchor cable to become slack.

Pre-cast concrete blocks of similar dimensions and rods can also be used. This can speed up the anchor installation process as they can be cast in bathes, well ahead of the time that they are required. Both these types of anchors should be back-filled in layers as described under anchors.

Timber log anchors are installed in a very similar manner, except the dimensions of the hole are different but the position of the front edge and the groove for the rod remains the same. The rod must have a large loop of 170mm bent and welded on the one end so that it can be slid around the timber log, the other end remains the same as for the concrete types.

The holes should be about 300mm wide and 2m long with the same depth of 1m. A small undercut must be made at the bottom of the front edge just large enough to accommodate half the diameter of the log. The log will nest snuggly in this undercut and will be seated against solid undisturbed soil. This will eliminate any “creep”. Back-fill as before.

STEP 6

The anchor cables or stay-wires play an important role in the structure, as they carry a tension of about 1.4 times as much as the main suspension cable when the system is loaded. 

In the interests of economy and to virtually eliminate the joining of any main suspension cables, exact lengths of the main suspension cable plus 1m, may be laid out between anchor poles and cut-off. At the end of a drum of cable there will usually be a length of cable not quite long enough to reach all the way between two anchor poles. Cut this remnant up in exact lengths to suit your anchor cable requirements. These lengths can be calculated by multiplying the height of the pole above the ground by 2.9 or 3. Remember anchor cables are double the distance from the top of the pole to the eye of the anchor rod protruding above the ground.

Take cable off a drum by suspending it on an axel, a strong steel pipe with a crowbar through it works well. Place this axel on two trestles or between arms of a tractor’s three point hitch and then pull the cable off by rotating the drum. If a tractor is used it can be driven forward slowly and the end of the cable held in place. Have someone walk behind the tractor regulating the rotation of the drum to prevent an over-wind. If the drum is not rotated and the cable is merely uncoiled, the cable twits and then tends to untwist, at a later stage during the installation process, causing problems. 

Attach one end of the cable to the eye of the anchor rod with a vine line grip, loop the cable around the top of the pole above the coach-screw and pull it down towards the eye.

The top of the pole must then be pushed towards the anchor, leaning it about 2-3° off vertical and the cable being kept as tough as possible must then be attached to the eye of the anchor rod by a second vine line grip. When the system is loaded the anchor will return to vertical. Now attach an anchor cable to the anchor pole at the other end of the row in the same manner.

STEP 7 

While the ladder or the scaffold is still at the far side of the field, attach the main suspension cable to the top of the anchor pole just above the loop of the anchor cable with a vine line grip.

Now proceed across the field alongside the main suspension cable that is lying on the ground and attach it to the support poles by looping it over the coach-screws and penny washers. The cable will at this stage be some 3-4m or even more away from the anchor pole. 

Attach one end of the tension indicator with a D-shackle to the eye of the anchor rod and the other to the pin in the body of the wire rope puller, ("Tirfor") or to the hook on the body of the lever-hoist, if one is being used.

Place the pole cap on the top of the anchor pole, align it with the main cable and the anchor cables and secure it squarely with the four screws on the side. 

Attach the wire rope grip to the hook on the cable of the wire rope puller, release the cable and pass it over the pulley on top of the pole cap. Pull the cable down towards the main suspension cable at the same time pull this cable upwards so that the two meet and pass one another. Attach the wire rope grip to the main suspension cable and then slowly start to tension the cable with the wire rope puller. A lever hoist is used in the same manner except a wire rope sling is needed between the hook at the end of the chain, to pass over the pulley and connect to the wire rope grip with a D-shackle.

Continue tensioning the cable until 1400kg is indicated on the tension indicator, then stop tensioning. 

Pull the slack portion at the end of the main suspension cable towards the anchor pole and while keeping it taut, secure it with a vine line grip to the anchor pole across the anchor cable. (If this process is not done correctly, much of the tension can be lost when the pulling cable is slackened). Slowly release the tension by reversing the action of the wire rope puller or lever hoist.

When the tension in the main suspension cable is propagated to the anchor pole and the pulling cable is a little slack, release the wire rope grip and remove the pole cap. The main suspension cable should now be absolutely straight between poles and the anchor cables should be taught. This is the end of the structural portion of the system. The remainder of the work may be regarded as the plumbing portion.

Kort foto’s 

STEP 8

Make sure that the polyethylene lateral piping conforms to specification. 

Check the size, in South Africa terms, a 25mm pipe has an internal diameter of 26.7mm. ISO standards, used in almost all countries using the metric system defines a 25mm pipe as having an internal diameter of only 21.2mm and a 32mm pipe having an internal diameter of 27.4mm.

The area of a South Africa 25mm pipe is 560mm² and an ISO 25mm pipe is only 356mm²; this is some 37% less. Water flow will be drastically affected.  

An ISO 32mm pipe is therefore much closer to a South African 25mm pipe. Make quite sure that a polyethylene lateral pipe has an internal diameter of more than 26.5mm.

Make sure that the pipe is made from Low Density Polyethylene (LDPE) and not High Density Polyethylene (HDPE). This is important as HDPE is not flexible enough to seal properly around a Floppy Sprinkler push-in fitting. 

Check that the pipe is rated Class 4 and able to withstand 4 bar (400 kPa) pressure, that it is UV resistant (has an anti-oxidant added to it) and that it is made from virgin material.

Poly-pipe can usually be ordered in specific lengths if quantities are reasonably large, this can save time and money by eliminating joints and off-cuts. 

The length of the pipe may be determined as follows: 

1. The distance between two rows of poles, say 75m plus.
2. The height the pipe is to be suspended above the ground, say 4.7m plus.
3. The distance from the base of the pole to the saddle on the sub-main, say 1.7m plus.
4. The height the pipe is to be suspended above the ground minus 1.5m, say 3.2m
5. Then round this off to the next full meter.

John moet nog hierdie 2 punte oorskryf.

STEP 9

Connect the Laterals to the Sub-mainline, complete the mainline, filter, and pump installation. 

STEP 10