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Engineered Solutions. Flovac Launches New 2 inch Vacuum Valve

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Early vacuum sewerage systems are about to get a makeover thanks to the Flovac R&D team in conjunction with the Production team in The Netherlands. Clients from many parts of the world had struggled with getting reliable and easy to use vacuum valves to fit the earliest vacuum systems installed in the 1960’s and 1970’s.

Joel Lillienthal, the pioneer of modern vacuum systems granted early patents to Electrolux for the development of the vacuum sewerage industry in the early 1960’s. Those systems were developed using 2-inch (50 mm) vacuum valves as many were used for just grey water, marine applications and single house applications. Modern vacuum systems all use 3-inch or 90 mm vacuum vales and this is a requirement under most standards.

The 2-inch valves that were installed in many of those early projects used a membrane type valve and an old fashioned ball float controller, similar to what was used in old toilet cisterns. Both the membrane valve and ball float increased operational problems in these systems as did the smaller 2-inch size of the valve. As most plumbing fixtures within the house had a 3-inch clearance the vacuum valve became a choke point.

The development and use of 3-inch valves in the 1970’s reduced the rate of blockages and vast improvements to the technology in the years since have meant that vacuum sewers are the preferred alternate sewage system in many countries. Sadly most of these early vacuum sewers had corresponding size issues with smaller diameter pipes and small diameter collection pits for holding the vacuum valves. This meant that it was often impossible to replace the existing valves with modern larger ones.

Although there are still many hundreds of vacuum systems left from the sixties which are still working, they do have high operational costs and problems can be difficult to find. This has caused some anxiety around vacuum technology in area’s where these systems still exist.

2-Inch Valve Improvements

Flovac’s production team have been working for some time on developing a 2-inch valve to help out numerous clients from around the world. What clients had asked for was something that was

New Flovac 2-inch valve

very similar to our 3-inch valve.  You can read about all the benefits of the Flovac 3-inch ( 90 mm valve) here. Clients felt that it was the best valve and controller in the market and wanted as many of the same attributes as possible. What has been developed is very similar and includes the ability to unscrew the top half of the valve from the bottom without using any equipment. The controller also has a quick release key.  The internal free ball passage of the FLOVAC 2-inch interface valve is with 55 mm the biggest free ball passage in the existing market. This with the self-cleansing extra wide Y-body, results in higher efficiency and less chance of blockages.

Valve Monitoring Option

As an addition they have managed to make it compatible with either the cable or wireless monitoring systems.  A 2-inch valve is always going to be more susceptible to blockages so getting an alert when one occurs and in which valve it is occurring will cut down operational time considerably. Another very important reason for the use of monitoring with these old systems is that many suffer from infiltration from groundwater and stormwater. Some of these systems are now 50 years old, pipes and pits are cracking and breaking. Monitoring makes it possible to target specific areas for rectification, taking away the guesswork.

 

Grey Water Systems

The new Flovac-2 inch valve has not been developed for use in modern municipal system as only 3-inch valves should be used in residential area’s. One area that the 2-inch valve might find a market though is for when we do grey water only systems or smaller indoor systems. Grey water systems do not have solids and so there is little to no risk of blockages.

Flovac 2-inch valve with Grey Water Box

Please contact your closest Flovac office if you would like more information about the 2 inch valve. It will be on display at the worlds largest water industry expo at IFAT in Munich in May 2020.

 

Coping in a world with less water

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The Downside of Saving Water

In recent times severe water shortages in many parts of the world have led Water Authorities and consumers to rethink how water is used in households. Water restrictions in many areas have drastically cut the amount of potable water used, with car washing and garden watering severely restricted. Water savings devices have now been installed in many homes and many more products are now being developed. This is having a big impact on the way wastewater is taken from houses to be treated by municipal authorities.

Many municipalities will soon adopt policies allowing greywater to be re-used within the house or on the garden. Products such as water efficient showerheads, washing machines, and flow inhibitors on taps as well as low flush toilets are reducing how much wastewater is sent to the treatment plant for treatment. Community education programmes are also informing consumers about ways to reduce water use.

Wastewater can be categorised into two components; greywater and blackwater. The main difference between greywater and blackwater is the biological and solids content. Blackwater is essentially the water that has all of the solids in it and cannot come into contact with humans unless treated. Household wastewater can be broken down as follows:-

Greywater {f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} Blackwater {f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}
Showers Baths/Spa’s 33{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} Toilets 32{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}
Basin 5{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} Kitchen 7{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}
Laundry 23{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}
Total 61{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} 39{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}

In most cities and towns wastewater moves from houses via a gravity reticulation network to the treatment plant, where it is treated to an acceptable level and sent to an ocean outfall or into the ground for further long term treatment or increasingly recycled for use in industry or public areas.

Gravity pipework is laid with sufficient grade (1/60;1/80;1/100) to allow for water to push any solids down the pipe toward a pump station which will bring it back to the surface and then gravitate again to the next pump station, until ultimately it will bring the wastewater to the treatment plant. The pipework will sometimes need to be installed quite deep (5-10 metres) to minimise the number of pump stations required.

The Problem

There is however a problem in that current gravity sewer networks cannot cope with lower water flows in pipes in that it is water that transports solids down the pipe. If there is insufficient water, then there is no movement.

Gravity sewer mains are usually designed to allow for a 14{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} solid load in the pipe. The other 86{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} is water pushing the solids down the pipe. What happens if the solid load is 50{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} as has recently happened in parts of drought affected Australia.

In previous years water authorities have designed their pipework and pump stations based on between 200-240 litres per person per day (l/p/d) There was also an allowance made for peaking factors (higher water use at peak times such as in the morning or evenings) and they have also allowed for the risk of stormwater infiltration, due to illegal connections or broken pipes. This stormwater allowance is usually 3 times the average daily allowance and can have very high cost impacts on the pipework, pump-station and treatment plant requirements.

The current water shortages and water saving devices as well as the separation of gray and black water have led to a reduction in daily allowances to 150-180 litres per person per day (l/p/d). This suggests that wastewater infrastructure can be smaller and therefore use less power but what has in fact been occurring is significantly higher maintenance requirements and even water use by the water authorities. As gravity systems require the use of water to move solids down the pipe network, less water coming from the household is creating blockages in greater numbers leading to odour problems as well as increased water and labour costs to manually flush the pipes of solids.

240 l/p/d 180 l/p/d 70 l/p/d *
Blackwater 94 70 70
Greywater 146 110 0
Total 240 180 70

* Greywater reuse at the house

In recent years many municipalities and water authorities have adopted the use of vacuum sewerage systems as their reticulation networks in areas where there is a high water table or very flat land or where it is too difficult to install a traditional gravity network. The very first vacuum sewers were installed in the late sixties but there has been a sharp increase in recent years as operators discover the lower operating cost versus their existing gravity systems. All pipework is laid at minimal depth and laid at a flat 1/500 grade. There is usually only one pump station required which has reduced the energy costs in the system. Differential air pressure is the driving principle and all solids and water are transported via air rather than water. The wastewater travels at a high velocity (4-6 metres per second) and so no blockages occur. As it is a tight system, damaged pipes are immediately repaired and no allowance is required for stormwater infiltration saving money and energy with the sizing of the infrastructure.

Vacuum systems have been used for many years to move 100{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} solids this is common in many industrial applications and even in the home. This also applies to wastewater removal. The Flovac sewerage system can easily handle quite high concentrations of solids in the pipe.

Conclusion

For countries or towns with very little water available or have diminishing resources like Botswana, India, Oman, Australia and many others places, Flovac systems are really the only system that should be considered for removal of sewage.