Monday, 31 January 2011

Hands-on Learning from our Farm Water Scheme

In recent months with the seasonally warmer weather we have been using and relying our farm water scheme (refer previous post) to provide drinking water to our sheep via the portable troughs. Given that the Ooma Water Scheme is not yet finished we are using gravity fed dam water to fill the Rhino tank as the stock water source.

What follows are some of the practical hands-on learnings we have had so far. I’m sure our experiences are not unique, but figured they were worth sharing.

Frogs in the Rhino Tank
When we had the Rhino tank installed we requested that ‘dust and vermin’ proofing be installed. Our thinking was that it would keep dust, mice, locusts and other small critters out which in turn would help maintain water quality and reduce the risk of pump, pipe and trough valve blockages. The ‘proofing’ is achieved by putting a filler of sorts between the corrugated zincalume roof sheeting and the supporting wall of the tank. The contractor from Molong who did the installation did a great job of constructing the tank but a while after we filled the tank we began to hear frogs in it during the night. It transpired that the contractor omitted to put the filler underneath one side of the access hole and also where the bracket that holds the ladder goes. The omission was a simple oversight but the learning is two fold: need to closely check the work completed and frogs can get through almost any gap.

Air Valves
There are air valves installed at every high point in the main line (4) and on every tank. Pockets of air in pipes act like physical blockages and can dramatically reduce flow rates. The air valves also play a critical role in allowing air into the pipes during intended of unintended rapid flow instances and prevent the polythene pipe from collapsing.

Two different brands of air valves were used by the contractor during the installation: one has a membrane mechanism to seal off the valve once the air has escaped and the other uses a small plastic ball that acts as the stopper. We have had trouble with several of the membrane air valves due to shavings of polythene pipe coming though the pipe and into the air release hole combined with the very high pressure of water in the pipes. The membranes have perforated meaning they do not seal properly and thus leak. We intend having these replaced under warranty. The faulty air valves are VYR brand and are actually manufactured by VYRSA in Spain! We strongly recommend that anyone looking to source air valves stay way from these.

When our scheme was installed the contractor placed small ball valves under only two of the four main line air valves. Without the ball valves it means that to fix a problem with an air valve the main pipe above the air valve has to be emptied of water. Whilst problems are likely to be very rare emptying the pipe takes time and is a nuisance. We have subsequently (ourselves) installed ball valves under the other two air valves.

Ball Valves
A few different brands of ball valve are installed along our scheme. This is not a problem per se but there are different features. For example, one brand has a mechanism that allows for the valve to be locked open (very handy) and another has a direction flow indicator on the side.

With one of the ball valves I’ve removed the handle completely to avoid the risk of it being closed accidentally by stock. We always have a shifting spanner in the ute which can be readily used to close the valve if necessary.

The above photograph shows standard hydrant layout with ball valve (handle removed) and air valve on top. The gate valve is 1.5 inch with male cam lock fitting attached. The safety connection hose is attached and runs to the trough (not visible). You can see the alloy female cam lock with two high quality hose clamps in place.)

Connecting hoses from the hydrants to the troughs
We bought high pressure safety hose from which we manufactured our hoses to connect the portable trough to the hydrants. There are female cam lock fittings on both ends of the hoses, and obviously male fittings on the troughs and hydrants.

Twice (so far) the clamps tightening the cam lock fitting to the end of the hose have “let go’. On both occasions the main 22,730 litre poly tank at the top of the farm emptied. In hindsight the cause of the cam lock fitting slipping out of the safety hose was three fold: 1) We bought cheaper cam lock fittings that have poor ribbing along the shaft that goes into the hose and thus there is less surface area for the hose to connect to the shaft 2) We bought conventional hose clamps that are narrower and more difficult to tighten. 3) The safety hose is quite thick and tends to soften when heated reducing the tightness between the hose and the shaft of the fitting. We have now purchased high quality cam lock fittings (manufactured or imported by Advanced Industrial Products in Brisbane) and the highest quality hose clamps, using two clamps per join. When clamping the hose to the shaft of the cam lock fitting we tighten as much as is possible, connect the pipe to the trough and fill the trough but then shut off the gate valve at the hydrant. Once the sun has properly heated the hose filled with water we tighten once more and repeat the process i.e. the clamps are tightened at least three times. So far so good!

Hose lengths of 5 metres seem to work well.

Checking Troughs
Given our experience we now make sure we check the troughs at least every two days. If we had cattle it would be essential to check them daily, especially during summer.

Low Pressure Safety Switch on the Pump Controller
Both times when the hose fittings let go we had the sheep in paddocks and were using hydrants located not far from the house … and thus not far above the house in terms of elevation. Our pump system has a low pressure safety mechanism that turns off the pump if the pressure in the pipe when pumping is low. There is a manual override in the control box. For us this is very handy, and in fact we did not even know about it at the time of installation. It means that there is a much lower risk to the solar system if something goes wrong while we are away.

Absences from the Farm
We now turn off the pump when going away for a few days, making sure that the top tank is full.

Location of the main storage tank
When designing the farm water scheme one of the toughest decisions was whether to locate the largest storage tank at the house or at the top of the farm. After several conversations with experienced farm water scheme operators we opted to have it at the house given 1) As far as the Ooma Water scheme goes it was very important to us to get the water on farm … and we then at least have it to use. The receiving tank will auto fill once the Ooma Scheme gets going. 2) We don’t need all of the stock water in our scheme to be pumped to the top of the farm as not all the tanks are at the top of the farm. Thus if we don’t need to pump it to the top of the farm it does not make sense to do so as it creates more wear and tear on the pump.

If the main tank had been installed at the top of the farm it would have been set up with a safety mechanism such that it only emptied to about 20 percent capacity, with the ability to access the 20 per cent in an emergency. When we had the problem with the hose fittings in both cases (as stated above) the main top poly tank emptied and we lost 22,730 litres each time. If the main tank was located at the top of the farm we’d have lost around 80,000 litres each time. It’s fabulous to have incorporated the ability to shut off the two other 22,730 litre tanks when not needed. These remained full and in reserve.

(The above photograph shows the end of the connecting hose where it attaches to the fixed trough fitting. The brass section is the pressure reduction valve).

Float Valves
In our view, given our water system has in excess of 100 metres of elevation / head, it can be classed as high pressure. Most of the farm water schemes to the north of us do not have more than around 40 metres of head to deal with. We bought a float valve for one of the troughs that the bloke in the shop at Forbes told us was specifically designed to handle high pressure. Given past excellent experience with this fellow we trusted his advice. During shearing we ended up at one point with about 900 sheep in one paddock. The paddock does not have a dam in it and the sheep would thus be solely reliant on the trough for water. When we filled the trough we found that the float valve ‘got the shudders’ and water was spilling over the side (despite the cover) and when the trough was very close to being full the float valve made an unbelievably loud ‘screaming’ sound.
We rang the fellow who sold us the float valve and he very quickly transferred the call to an irrigation specialist they work with. This subsequent fellow we spoke with explained that the float valve we’d bought was not suited to high pressure, high pressure float valves are available but were not in stock, and that there are pressure reduction fittings that can be purchased.

Pressure Reduction Valves
Continuing the above story, we called our trusty adviser, Phil Wells, who provided us with more detail about the pressure reduction valves and confirmed they were a good option. They are made from brass, are about 15 cm in length and can be purchased in a variety of diameters and pressure reduction outcomes. We ended up buying two 1 inch valves each costing a tad under $140 GST inclusive: one reduces the pressure by one half and the other to one third.

We installed the pressure reduction valves as part of the fixed fittings on two troughs. They work well and mean that we do not need special float valves.

In hindsight it was probably better to have set up cam lock fittings on the pressure reduction valves so that they could be added into the overall connections for the troughs only when needed. Our third trough does not have a pressure reduction valve on it and will only be used in paddocks where the water pressure is much less than at the bottom of the farm.

Hose Clamps
The high quality hose clamps we now are using cost about $6 each. One thing about them … it is more difficult to tell at a glance what the sizes are. When I returned home from buying them I found that one was a size smaller than the others. One needs to look VERY closely at the labelling to make sure it’s the right size.

Cam Lock Fittings
I asked several experienced people whether there was a difference in terms of functionality and durability between the plastic (or whatever the material is) and alloy cam lock fittings. The common response was ‘none at all’. Based on our own recent experience we have a different view … the non-metal cam locks fittings are not the go as they are more flexible and thus prone to leak while the trough is connected and the water is turned on. The alloy ones are made to much finer tolerances as well.

I’ve managed to find what seems to be a good brand of alloy cam lock fittings. They are made or sourced by Advanced Industrial Products in Brisbane and have the initials AIP on the handles of the female fittings.

Height of the Hydrants
We made the hydrants a tad too high out of the ground at about 800 mm. They should have been lower at around 400 mm to reduce the leverage from the trough connection hose when full of water. This then means that there is less chance of water leakage and damage to the hydrants from stock. On the other hand, having them higher does mean they are easier to see and locate.

We’ve still plenty more to learn!

No comments: