The new 1200mm Alaskan Yellow Cedar Woodstave Pipeline at Lake Margaret, Tasmania
Baywater & Liddell Power Stations
Ventomat Australia recently supplied their Series ‘RBXcb’ and ‘RBXb’ Air release and Vacuum Break Valves with Integral Surge Alleviation (“Anti-Shock”) Mechanism to Bayswater Power station. The valves are fitted on two large diameter rising mains that have been built to take advantage of the large variance of flow in the river and pump water from the Hunter River at Bayswater to the power station reservoir during flood events.
The Ventomat valves in this instance were modelled by the consultant to mitigate surge and water hammer as well as provide the standard air valve functions of high volume air release and air intake and pressurised air release.
Ventomat Valves have also been used for 7+ years at Liddell Power Station across the road on ash slurry lines and have prevented pipe bursts on several occasions according to the Plant Owners Coal Ash and Dust Specialist.
Bayswater Power Station is renowned to be one of Australia’s largest power stations, producing approximately 17,000 GWhs of electricity a year. This is enough power for 2 million average Australian homes and families. It’s most characteristic feature is the four evaporative cooling towers as seen in the below picture from Liddell’s ash slurry lines installed with Ventomat Series ‘RGX’ Valves for sewerage / slurry applications.
Goulburn- A short case study on the role of Ventomat Air Valves in pipeline protection
Goulburn, located south of Sydney is situated in the scenic Southern Tablelands of New South Wales and has a population of 27 000. It was the first inland city in Australia and was well known for producing fine merino wool which is demonstrated by the major tourist attraction, the big merino.
Goulburn Mulwaree Council look after the town’s water supply. Ventomat Air Release and Vacuum Break valves with integral surge alleviation mechanism (pictured below) were recently installed in the rising main to the high level reservoir. On a recent trip to Goulburn during a visit to the valve installation shown below it was mentioned that prior to Ventomat valves being installed there were pressure spikes from surge and water hammer causing some concern to council staff. After the Ventomat valves were installed the pressure spikes were virtually eliminated.
The entire range of Ventomat Air Release and Vacuum Break Valves for water, wastewater and irrigation are supplied as standard with an integral surge alleviation mechanism.
How Does It Work?
During pipeline filling or power/pump failure where column separation occurs, the valve will sense the water column(s) moving rapidly to the high point and the ‘Anti-Shock’ float closes under the presence of air. The valve outlet is then reduced, resulting in deceleration of the approaching water column due to the resistance of rising air pressure in the valve. Basically the valve uses the pipeline as a surge vessel.
Due to their success and extremely low maintenance requirements, Ventomat Air Valves will be used to replace air valves currently installed in Goulburn’s pipeline system.
Lake Margaret Power Station
Pictured below is a section of the historic Lake Margaret timber pipeline that has been recently re-built utilising the superior technology provided by Ventomat Air Release and Vacuum Break Valves with Integral Surge-Alleviation Mechanism.
In the picture below you can see the new Alaskan Yellow Cedar pipeline with a 100mm Ventomat Series ‘RBX’ Air Valve.
The Old Pipeline
In 1911 the Mount Lyell Mining and Railway Company at Queenstown, Tasmania built a hydro-electric power station at Lake Margaret, it is one of the oldest hydro-electric plants in the Southern Hemisphere.
In the early 1980’s it was taken over by Hydro Tasmania and in 2006 it was closed down due to safety concerns spurned from the 70 year old ‘King Billy’ pipeline springing many leaks and the pipe requiring constant maintenance that was putting operators at risk.
According to Earthmover and Civil Contractor Magazine it was dubbed “the world’s biggest soaker hose” (see picture below). In early 2007, during a period of drought, the leakage in the pipe was so bad that it drew down the level of Lake Margaret by 10% from the leaks alone. One way the operators fixed the leaks was by flushing a bag of saw dust down the pipeline (Huon Pine worked the best because of its excellent anti-rotting properties).
The King Billy Pine used to construct the pipeline was not actually the first material used (wood was the chosen material as it was cheaper than other materials at the time such as steel and was also expected to last longer).
In 1913 The Australian Woodpipe Company determined that the local King Billy pines’ properties were not good enough for the construction of the pipeline and subsequently Oregon Pine was imported from Canada. This deteriorated very quickly and had to be replaced in 1938 when the local King Billy Pine was utilised and the line remained in service until 2006.
The King Billy Pine is named after William Lanne or King Billy who was the last full-blooded Aboriginal male in Tasmania and after his death, the tree was named after him. The events after his death were contoversial to say the least. His skull was stolen and replaced with a white mans skull and his body exhumed illegally. The stolen parts were sent to England for research and display against the wishes of local authorites and the person responsible was rewarded for this dispicable deed with a gold medal from the Royal College of Surgeons in England. All of this was for nothing as the skeleton was never seen again and the skull never made it to England and was lost.
The tree is now listed as a threatened Australian plant and has been found to make an excellent sound quality in stringed instruments, particularly the classical guitar.
The New Pipeline
The new pipeline was designed by Johnstone McGee and Gandy (JMG) in Hobart and was constructed by Hazell Bros with technical assistance from the International Tank and Pipe Company from Portland Oregon. The old “King Billy” line was preserved in three sections one of which can be seen below.
Local lobbying groups were against the shutting down of the power station and were very much for rebuilding the pipeline in woodstave as both plant and pipeline are major tourist attractions and an important part of the local history. The clean energy was also a major point to consider and during 2006 when blackouts occured, the power station allowed the copper mines to remain on line and functional and prevented mine chambers from flooding.
In 2009 JMG, Hazell Bros and Hydro Tasmania were jointly awarded for engineering excellence at the Engineers Australia Tasmania Awards Night for the project. A self propelled trolley was designed for construction and maintenance of the pipeline, a worlds first for pipeline design and construction.
Ventomat Air Release and Vacuum Break Valves with Integral Surge Alleviation Mechanism
Ventomat Air Valves were the only choice for such an important pipeline as all Ventomat Air Valves come integral with the original “Anti-Shock” surge and water hammer alleviation mechanism.
The Ventomat valve range provide the standard functions during normal operation and then the “Anti-Shock” float will automatically come into action during a surge event such as during a blackout where the water column separates at the high point. As the pumps re-start and the water column rejoins, very high rates of air are released very quickly and the valve will react to this and control the release of air in order to protect against over pressures.
A good analogy to describe this unique function is to look at it like an airbag in a car i.e. it is there to protect and cushion the blow when required.
Another important aspect for chosing Ventomat is the full flow characteristics. All Ventomat valves are full flow which means the inlet, outlet and flow areas all equal the size of the valve. Grant Atherton from JMG pointed out that at one point a boulder fell from the mountain and destroyed a large section of the pipeline, by utilising the full flow characteristics of the Ventomat you can be assured that large volumes of air will be “sucked” into the pipeline and protect it from negative pressures during such an event.
To help determine sizing and postioning of valves the Ventomat CATT (Controlled Air Transfer Technology) Program was utilised. This is a sizing and positioning program developed by Ventomat and your free copy can be obtained by contacting Ventomat Australia (see contact details below).
Ventomat Air Valves provide four functions:
The valves are virtually maintenance free, self cleaning made from superior materials and are proven in over 10 years in the Australian market and over 30 years in world markets. For more information go to: www.ventomat.com.au
Jeremy Kerrigan at: firstname.lastname@example.org (MOB: 0414 552 169)
Joel Campbell at: email@example.com (PH: 02 8814 9699)
North South Interconector Pipeline
Below Ventomat Australia Pty Ltd was chosen to supply air valves for the pipeline and pump stations for the North South Interconnection System Project.
Ventomat Australia Pty Ltd was chosen to supply air valves for the pipeline and pump stations for the North South Interconnection System Project. The installation of air valves in the pipelines aims to maintain a steady pressure in the system to ensure a secure, reliable and consistent water supply. Ventomat Australia also supplied advice on the sizing and positioning of air valves and surge and water hammer analysis.
The first Ventomat air valves were installed in Australia in 1997. Ventomat Australia Pty Ltd commenced operations in 2005 as the supplier of Vent-O-Mat Air valves. It is a subsidiary of Dynamic Fluid Control (Pty) Ltd of South Africa, one of the largest valve manufacturers in the Southern Hemisphere. The company specialises in the Vent-O-Mat Air Release and Vacuum Break Valve which comes with an integral “Anti-Shock’ Mechanism for surge / water hammer protection. They also supply and manufacture RF Pinch Valves and Insamcor Knife Gate Valves for slurry/tailings and sewerage. Ventomat Australia’s service extends to customers throughout Australia and the Asia/Pacific rim. Ventomat’s other projects include the replacement of air valves on the large diameter Warragamba pipelines near Sydney, as well as replacement of air valves for Melbourne Water and Water Corporation in WA. Ventomat Australia has recently supplied air valves for the Gold Coast, Sydney and Melbourne desalination plants as well as for the Glenelg to Adelaide Pipeline in South Australia, the Sugarloaf pipeline in Victoria and the Lake Margaret Timber Pipeline in Tasmania and is a preferred supplier for BHP Billiton, Rio Tinto and Fortescue Metals Group.
Nyngan is located between Narromine and Bourke, 583 km north-west of Sydney. Most people will remember Nyngan for the 1990 floods, when the entire town had to be evacuated by helicopter. This was despite the efforts of the townspeople building a levee out of more than 200 000 sand bags, to no avail. The entire town was flooded after the Bogan River rose to 5.2 metres which was 1 metre higher than the previous record.
After the event a levee bank was built around the town to prevent future occurrences.
Unfortunately the first time it was tested large sections of pipe collapsed and completely flattened. This was due to the negative pressure induced into the system as the water rose and then flowed away from the high points along the levee bank. No air valves were included in the system.
The sections of steel pipe that collapsed were replaced and Ventomat Air Release and Vacuum Break Valves with an Integral Surge Alleviation mechanism were introduced along the levee.
The Ventomat range of air valves are unique for the following reasons:
This is an important fact as a lot of air valves sold in the market place do not have a full flow capacity meaning in similar circumstances damage to the pipeline could still occur if this is not taken into account when the valves are sized.
An Important design feature of Ventomat is a cylindrical float. All air valves “suck” air as a vacuum occurs. Air valves with ball or spherical floats react differently to the Ventomat valve. As air rushes over the top and around a ball float it will create low pressure on the top of the ball, causing the ball to lift up to the outlet and greatly reduce the air intake volume. This is known as the ‘Venturi Effect’ and can be demonstrated by placing a ping pong ball in a small funnel and blowing into the funnel. You would think the ball would fall out but it is held there by the negative pressure formed on the top of the ball. This is prevented by Ventomat valves.
See the Venturi Effect: http://www.youtube.com/watch?v=13eoSasj4hw
The following pictures show two different air valve installations, one is a bore pump operated by Riverina Water just outside the racecourse (which you can see in the background) in Wagga Wagga (Series RBXb,16 Bar rated), this valve set up was demonstrated during the 2005 Pipes Wagga Wagga Field Day . The other is a sewerage pump station for Wagga Wagga City Council (Series RGX short band 3.8 bar rated).
Example One - Riverina Water, Bore Pump
This is a good example of how a Ventomat air valve should be installed for a submersible / deep well pumping application. Firstly, a Series RBXb should be used. The Series RBXb has a spring on the top of the valve that holds the top / ‘Anti-Shock’ float in the closed position. This means that the outlet is reduced by approximately 35 times during high volume air release ie pump start up while still allowing full vacuum protection. This causes the air to be compressed when it is being released (due to the relatively small outlet orifice). This will cause backpressure that will slow the water velocity in the riser to an acceptable level so that no damaging pressure spikes will occur upon closure of the valve (basically using the pipeline as a surge tank).
A large or full diameter tee is also being used which will, in conjunction with the above set-up, create a separation point for the mixture of water and air that tends to get pumped up the riser upon pump start up. This will stop splashes of water hitting the lower floats of the air valve that will confuse the valve, thinking it is full of water, and closing it prematurely.
In summary the above set-up will ensure all air is released as quickly as possible without causing excessive pressure upon start up.
Note: an isolating valve should be installed below the air valve to enable the valve to be removed if necessary without having to shut the main down.
Example Two – Wagga Wagga City Council Sewerage Pumping Station
The above installation is sewage pump station about 5-6 Km’s out of town. This is a short pattern RGX air valve, this means it is shorter than the conventional 10 bar rated valve (approx 600mm in height). Pictured here is Len Kennedy from the council and Neil Mannix from AVK. They are standing next to a big bed of mulch that is used to remove any odour from inside the pump station. The air valve on the wall has below it a big white mark where the wall has been stained by the previous sewerage air valve, which leaked profusely. The Ventomat design overcame the problem in this instance by way of its long thin body, this design means only 2 metres head (20kPa) is required to effectively form an air pocket in the valve to keep sewage away from the working parts of the valve. With the previous design valve with a fatter body approximately 8 metres of head is required to form the air pocket. At this pump station there was not much pressure at times.
Ventomat air valves will be used on future applications around Wagga Wagga.