One of the constant challenges ofmaintaining wastewater systems incyclone prone areas is ensuring thatyour equipment is always operationalin the face of adverse conditions sothat public health and environmentaldisasters are averted.

As part of this requirement, GrahameDunstan, Co-ordinator for WastewaterServices for Cairns Regional Council(CRC), explored the options foremergency pumping during poweroutages at the White Rock #1 pumpstation. The solution had to helpensure that CRC's wastewater servicesin the greater Cairns area remainedoperational and effective during tropicalstorms and in emergency situations.

'Experience has taught us that duringextreme weather conditions and inemergencies not all your equipment mayperform the way you would expect.So it's important to try to implementmechanisms that will help safeguardagainst poor performance and makea system as failsafe as possible,'explained Grahame.

The council currently has numerous emergency generators to help maintainwastewater services in the event of loss of mains power.

'Our generators are not always onehundred percent reliable. We have hadsituations where an emergencygenerator has failed to kick inwhen it was most needed. So for us,generators can be a liability in anemergency,' he said.

Grahame undertook some research, comparing pumps, associated costs andtheir benefits before deciding that an emergency stand-by pump was aviable alternative to installing anothergenerator and would help improveredundancy of the system.

Already familiar with the Gorman-Ruppname he looked closely at the company's

The Gorman-Rupp V6-SCP stand-by pump.

Autumn 2012 Issue 01

Energy Efficiencyin WastewaterPumpsWith increasing energy costs and emergingcarbon dioxide taxes, engineers anddesigners are carefully scrutinising theenergy efficiency of wastewater pumps.In doing so, the responsibility to reduceenergy consumption needs to be carefullyweighed against any ramifications this“improved” efficiency may cause.

The McNally Institute says ... ”Highefficiency is desirable, but it will be amaintenance nightmare. High efficiencymeans tight tolerances and smoothpassages ... you will spend a lot ofdowntime and money trying to maintainthose two requirements”.

There are many aspects that need to beassessed when evaluating sewage pumpefficiency. Consideration needs to begiven to the pump's non-choking capabilityand the ease with which a choke can beremoved. It makes no sense to installthe most hydraulically efficient pump,only to have to have it serviced daily toremove blockages.

Ensure the pump is easy to access andmaintain. If accessing and maintaining thepump is not a simple process, removinga blockage or troubleshooting could proveto be a major and costly operation.

(continued on page 2) (continued on page 4)

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Cairns Regional Council improvesredundancy of its wastewater systemby partnering with Hydro Innovations

Cairns Regional Council improves redundancy of itswastewater system by partnering with Hydro Innovations(continued from page 1)

emergency stand-by pumps and chose to partner with Hydro Innovations,Gorman Rupp's authorised distributor in Australia.

'We were already using other Gorman-Rupp equipment and their track recordto date was excellent. Their products are very reliable and robust. We searchedfor a local supplier and found Hydro Innovations.

They were very professional and helpful in meeting our needs for an emergency stand-by pump,' explained Grahame.

To meet their requirements, Hydro Innovations installed a self-priming, centrifugal, diesel pump with auto-start. Called a Gorman-Rupp V6-SCP, theabove-ground pump has a suction line that goes down into the wet well and afloat switch that activates the auto-start. The unit only runs when required andremains silent at all other times.

The V6 provides superior solids-handling and increased pressure capabilities.It delivers higher pressures and flows than any other self-priming sewage pumpon the market and is also the most efficient pump in its class.

As with other Gorman-Rupp sewage pumps, the V6 is fitted as standard with aunique and patented self-cleaning wear plate system that enables the pump to handle stringy materials and rags that would block other pumps.

Enclosed in a sound-attenuated metal canopy, the V6 emits low noiselevels. Lockable doors prevent unauthorised personnel from tampering withthe pump, fuel, engine or controls. Fuel capacity allows for a minimum 24 hoursof continuous operation.

According to Grahame the cost to purchase the V6 was comparable with thecost of buying another generator. In addition, it also eliminated the needto have to install variable speed drives in the switchboard to make thegenerator operational.

Since having the stand-by pump installed in early 2010, Grahame and histeam have seen the V6 perform under emergency conditions.

'During Cyclone Yasi, we had to make use of the pump and it performedoutstandingly. It kicked in straight away and did what it was meant toeffectively,' said Grahame.

Apart from reliability Grahame also found that the Gormann-Rupp V6required less fuel to keep it operational.

'Each of our generators is eight times more expensive to run when compared tothe V6 and the maintenance costs associated with the generators are far higherthan those of the V6. The generators are also people intensive to maintain.Whereas the V6 requires less maintenance and uses up less of our people's time.

'The V6 pump has helped reinforce the operational capability and efficiency ofour wastewater system during an emergency situation. It's reassuring to knowthat we have the V6 in place,' explained Grahame.

'Choosing to partner with Hydro Innovations was also the right decision. Theygrasped what was required immediately, have a very good understanding of theirproducts and their backup service has been excellent,' said Grahame.

Safety is always the number onepriority. Electrical pumps come withthe risk of electrocution. So alwaysmake sure the pump is switched offand be vigilant of live wires.

Choose pumps that are easy to accessand maintain. Always refer to thepump's operational and maintenancemanual when performing any routinework.

Always use good quality gauges onyour pumps. Gauges are your“window” to a pump's performanceand your number one troubleshootingtool.

If your centrifugal pump is a selfprimer, select a suction line that islarge enough to avoid NPSH problems,but small enough to keep primingtimes reasonable.

Keep a spare rotating assembly foremergency break-down.

A good pump will have oil sightglasses for bearing oil or seal oil ifpertinent. Keep regular checks onthese to ensure that correct oil levelsare maintained and that the oilremains free of impurities.

Do quarterly shut-head readings toensure the pump is delivering the desiredperformance. Keeping pump clearances“tight” has several advantages:a. Energy use is kept to a minimum.b. Parts wear slower as less abrasivematerial is passing wearing surfaces.c. Solids handling pumps choke lessif clearances are at their factorysettings.

Remember to check the belts of anyvee-belt driven pump regularly andre-tension when necessary.

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MaintainingCentrifugal Pumps

Hydro Innovations would like to introduce the latest range of acoustically rated, dieseldriven sewage pumping bypass units. Working in collaboration with our customers andour supplier, Gorman-Rupp, these units have been purposely designed to meet theneeds of Australian water authorities and councils.

New Emergency Sewage BypassUnits ReleasedOver the past few years the use of Variable

Frequency Drives (VFDs) in pumpingapplications has increased. There are manyreasons for their rising popularity. Not onlydo they allow operators to vary pumpspeeds to match in-flows or maintainconstant pressures, they can also improveequipment life by soft starting andstopping, reducing shock on start-up aswell as water hammer when stopping.

The price of VFDs has also been fallingsteadily over time, making them a veryaffordable and attractive option. In someinstances where power cable lengths arelong, savings in capital costs are possibleas less current is required to travel throughthe cables to start equipment.

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At the heart of these units are the Gorman-Rupp Ultra V and Super T series sewagepumps. Driven by the latest in diesel engine technology, these pumps feature uniquecontrols and ancillary equipment.

The new units are all equipped with non-return valves, air release valves and casingdrain kits. The drain lines from the air release valves and casing drain kits are pipedto threaded connections in the canopy walls to make it easy for operators to attachlines back to the wet well. Once connected, the units are fully operational.

The controls have been specified to suit the needs of Australian operators. Theyfeature all the usual safety shut-down features, as well as the ability to convey thisinformation via telemetry systems. In addition, the controls detect “no-flow” situationsand low fuel conditions.

Other standard features of these units include self-contained, bunded fuel tanks; raincaps for the exhaust; a polycarbonate panel on one door to view the controls and soundattenuation of 67dB(A) at 7 metres.

The new diesel driven sewage pumps can deliver flows from just a few l/s through to200 l/s and with heads to 100 metres.

For more information on these units please call Hydro Innovations on (02) 9647 2700or email info@HydroInnovations.com.au

VFDs on Pumps

In particular, VFDs are proving invaluablewhen coupled with self-priming pumps.Self-priming pumps are on the ascent inboth municipal and industrial wastewaterapplications as well as in mining and evenwater transfer applications. They delivertrue life cycle cost benefits, easy access aswell as tangible OH&S advantages.

When combined with a VFD, the operator isprovided with greater control over thespeed of the self-priming pump's motorand therefore, its overall performance.

The Gorman-Rupp XXXXXX

Example of typical VFD unit.

The hydraulic efficiency of the pumpand its ability to maintain its hydraulicperformance also needs to be examined.

There are also some hidden inefficienciesthat need to be considered when evaluatingpump efficiency. This is particularly thecase with the most commonly used pumpin the sewage system - the submersible

pump. Items that “hide” during scrutinyare discharge connection losses, and thelowering of delivered efficiency duringthe periods between wear ring renewaland wear ring replacement time.Efficiencies can quickly dissipate whenclearances start to “open up” with wear.

For instance, in the case of submersiblepumps that rely on radial clearances,the only way to change their wearingrings is to open the wet well lids, hoistthe pump from the pit and then send it tothe workshop where the wearing ringsare chiselled out.The process is arduous,time consuming and far from efficient.

Submersibles that use axial clearancesare slightly more efficient but they stillneed to be pulled from the pit, cleanedand their clearances adjusted via jackingscrews.

Assessing the efficiency of a sewagepump is complex. The subject is coveredin great detail in a white paper entitledSelecting the Right Sewage Pump, Don'tLose the Pump Efficiency Game. ContactHydro Innovations to obtain a free copy.

Hydro InnovationsHydro InnovationsUnit 1, 26 Day StreetSilverwater NSW 2128

Telephone: (02) 9647 2700Fax: (02) 9647 2709www.HydroInnovations.com.au

DisclaimerAny representation, statement, opinion oradvice, expressed or implied, in this publicationis made in good faith but on the basis thatHydro Innovations, its agents and employeesare not liable (whether by reason of negligence,lack of care or otherwise) to any person for anydamage or loss whatsoever which has or mayoccur in relation to that person taking or nottaking (as the case may be) action in respectof any representation, statement or advicereferred to in this newsletter.

UnsubscribeIf you do not wish to receive a copy of PumpWiseplease email: ggrant@HydroInnovations.com.au

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Energy Efficiency in Wastewater Pumps(continued from page 1)

VFDs on Pumps(continued from page 3)

When considering the efficiency of a sewage pump remember to asses the following key criteria:

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Sewage Pump Efficiency

The non-choking capability of the pump

How easy it is to remove a choke

How easy it is to maintain the sewage pump

The hydraulic efficiency of the pump

The ability of the pump to maintain its hydraulic efficiency

A self-priming pump needs to run fastenough to prime, but sometimes this isfaster than the pump needs to run toprovide the pumping duty. A self-primingpump may also be required to pump deepinto a wet well. Two factors that affect theNet Positive Suction Head (NPSH) safetymargin are the friction losses through thesuction line and the NPSH required bythe pump. In both cases, a VFD can helpnegate these elements.

Where the pump needs to run fast to prime

(say 1800rpm), but has a slower duty

speed (say 1400rpm), a VFD can eliminate

the problem. The VFD simply drives the

pump at 1800rpm till it primes (a limit

switch on the non-return valve can send an

“I'm pumping” signal to the VFD), and then

it helps the pump drop back to 1400rpm.

Where a very high suction lift is required,a pump's “off level” can be “reached” byslowing the pump down at the end of a“pump-down” cycle to reduce both suctionline friction losses and the NPSHr of thepump.

As can be seen, the benefits of VFDs inpumping applications are numerous and insome cases, they can be critical in beingable to satisfy the duty completely.